Czym różnią się magazyny energii BESS od klasycznych instalacji

Zrozumienie zagrożeń z eksploatacją tych urządzeń jest kluczowe dla zapewnienia bezpieczeństwa personelu oraz samych instalacji elektroenergetycznych. Magazyny energii stanowią kluczowy element transformacji energetycznej i stabilizacji pracy systemów elektroenergetycznych. Ich rosnąca skala oraz integracja z siecią powodują jednak, że klasyczne podejście do bezpieczeństwa instalacji elektrycznych jest niewystarczające.

W systemach BESS występują jednocześnie:

• napięcia DC oraz AC
• bardzo duże prądy zwarciowe,
• źródła energii chemicznej (Li-Ion, LiFePO₄, NMC)

Powoduje to konieczność analizy zagrożeń w sposób holistyczny. W przeciwieństwie do klasycznych instalacji elektroenergetycznych, systemy BESS wymagają uwzględnienia sprzężonych zjawisk elektrycznych, termicznych oraz chemicznych, co znacząco zwiększa złożoność analizy ryzyka.

Kluczowe zagrożenia w eksploatacji magazynów energii

Eksploatacja magazynów energii wiąże się z kilkoma kluczowymi kategoriami zagrożeń, które wzajemnie na siebie oddziałują. Najważniejsze z nich to:

• porażenie prądem elektrycznym (AC i DC),
• poparzenie od łuku elektrycznego (AC i DC),
• pożary i zjawisko thermal runaway
• zwarcia zewnętrzne
• zagrożenia chemiczne (płyny i gazy).

Kluczowe zagrożenia w eksploatacji magazynów energii

Porażenie prądem DC

Porażenie prądem stałym (DC) w systemach magazynowania energii stanowi szczególnie istotne zagrożenie ze względu na rosnące poziomy napięć, często powyżej 800 VDC. W przeciwieństwie do prądu przemiennego, prąd stały nie posiada naturalnego przejścia przez zero, co powoduje, że skurcz mięśni jest ciągły. Długotrwały przepływ prądu przez ciało zwiększa ryzyko poważnych uszkodzeń tkanek, zaburzeń pracy serca oraz głębokich oparzeń wewnętrznych. Dodatkowo, w systemach BESS także występuje napięcie zmienne (AC).

Do porażeń może dochodzić podczas :

• prac eksploatacyjnych
• uszkodzeniu modułów baterii (jeśli napięcie przekracza poziom napięcia 120 VDC)
• uszkodzeniu izolacji

Dodatkowo warto pamiętać, że wg PN-EN 50110 izolowanie miejsca pracy nie ma pełnego zastosowania w pobliżu baterii. Nie możemy w pełni „wyłączyć” lub rozładować energii baterii. W praktyce stosuje się:

• procedury prac wokół baterii
• środki ochrony indywidualnej
• rozwiązania techniczne (sekcjonowanie baterii, modułowy projekt, zabezpieczenia na poziomie modułów itd.).

Łuk elektryczny w systemach BESS

Zwarcie łukowe jest realnym zagrożeniem podczas eksploatacji w systemach BESS. Napięcia DC przekraczają 120 VDC, ale na obecną chwilę do 1500VDC (granica niskiego napięcia dla DC wg PN-EN 50110). W instalacjach DC energia łuku elektrycznego jest bardzo mocno zależna od prądu zwarcia i możliwości źródła do potrzymania łuku elektrycznego. Do zwarć łukowych dochodzi podczas:

• uszkodzenia izolacji
• prac eksploatacyjnych (błąd ludzki)
• błędów instalacyjnych
• czynników środowiskowych (wilgoć, zanieczyszczenia, powódź)
• zwarcia wewnętrznego i zewnętrznego

W przeciwieństwie do zwarcia pełnych (metalicznych), zwarcie łukowe charakteryzuje się pewną impedancją łuku elektrycznego co ma swoje konsekwencje w postaci :

• problemów z detekcja prądów zwarć łukowych
• problemów z wyłączaniem prądów zwarć łukowych
• wydłużonym czasem detekcji i wyłączenia

Charakterystycznymi cechami łuku elektrycznego są:

• temperatura dochodząca do 19 400°C
• promieniowanie świetlne (UVA/UVB)
• wzrost ciśnienia (fala uderzeniowa)
• Jonizacja i podgrzanie otaczającego powietrza
• emisja stopionego metalu
• odłamki poruszające się nawet z prędkością do 1100 km/h
• fala dźwiękowa nawet do 160dB

Thermal runaway

Zjawisko thermal runaway stanowi jedno z najpoważniejszych zagrożeń w magazynach energii. Thermal runaway jest efektem utraty kontroli nad bilansem cieplnym ogniwa, najczęściej inicjowanym przez uszkodzenia mechaniczne, przeciążenia elektryczne, wysoką temperaturę lub defekty wewnętrzne. Grafika poniżej bardzo prosto opisuje przyczyny, mechanizm oraz konsekwencje.

Charakter zagrożenia zależy od technologii i chemii użytej do produkcji ogniw.
Najbardziej narażone są ogniwa wykonane z :

• Lithium Cobalt Oxide (LCO)
• Nickel Manganese Cobalt (NMC)

Najmniej :

• Lithium Iron Phosphate (LFP)
• Solid-State Batteries (stały elektrolit)

W bateryjnych systemach magazynowania energii szczególne zagrożenie stanowi obecność substancji o właściwościach utleniających, które w warunkach awaryjnych (np. thermal runaway) mogą znacząco zwiększyć intensywność pożaru oraz umożliwić jego rozwój niezależnie od dostępu tlenu z otoczenia. Zgodnie z wymaganiami NFPA 400 oraz NFPA 704, systemy zawierające takie materiały powinny być odpowiednio klasyfikowane i oznakowane, a ich eksploatacja powinna uwzględniać scenariusze uwolnienia substancji utleniających.

Do inicjacji tego zjawiska dochodzi w wyniku:

• Uszkodzenia mechaniczne – przebicie, zgniatanie, zwarcie wewnętrzne
• Przeciążenia elektryczne – przeładowanie, nadmierne rozładowanie, zbyt duży prąd
• Oddziaływanie temperatury – wysoka temperatura otoczenia, pożar, brak chłodzenia
• Wady wewnętrzne ogniwa – defekty produkcyjne prowadzące do zwarcia w czasie

Zwarcia w obwodach DC

Zwarcia w magazynach energii mają szczególny charakter ze względu na obecność ogniw bateryjnych o dużej wydajności prądowej. Skupiamy się tutaj na bateryjnych magazynach energii stosowanych w instalacjach przemysłowych czy sieciowych. Dla podania skali, systemowe magazyny buduje się z kontenerowych 20’ BESS o mocach typowo do 5MWh /1300VDC (12*1P416S) – co znaczy 12 klastrów po 416 modułów 3.2 V.

Systemy budowane z takich kontenerów osiągają wartości :

• Edwards & Sanborn Solar – USA, California, 821 MW/3287MWh
• Collie Battery – Australia, 560 MW/2240MWh
• Bisha BESS – Saudi Arabia, 500 MW/2000MWh

W dużych systemach magazynowania energii zwarcia mają znaczenie nie tylko lokalne, ale również sys temowe. Pełnią też różne role od magazynowania energii lokalnie do szybkiego wsparcia częstotliwości (frequency support). Z perspektywy magazynu energii prąd zwarciowy możemy podzielić na :

• zewnętrzny
• wewnętrzny

Ten sam podział można zrobić na poziomie samego ogniwa tj. zwarcia występujące poza ogniwem oraz występujące w ogniwie np. z powodu przebicia membrany elektrolitu przez formację dendrytów.

W odróżnieniu od klasycznych systemów elektroenergetycznych, prądy zwarciowe w systemach BESS są w dużej mierze determinowane przez charakterystykę układów energoelektronicznych (PCS), co wpływa zarówno na poziom energii łuku elektrycznego, jak i skuteczność jego detekcji.

Skutki eksploatacyjne zwarć prowadzą do:

• przyspieszonej degradacji ogniw,
• wyłączenia instalacji
• zagrożeń podczas eksploatacji

Skutki systemowe w przypadku dużych instalacji mogą prowadzić do:

• zaburzenia stabilności sieci,
• kaskadowych wyłączeń
• pożar instalacji

Normy i regulacje — UE, USA, Chiny

Świadomość zagrożeń elektrycznych znalazła odzwierciedlenie w szeregu regulacji prawnych na poziomie europejskim i krajowym:

• Dyrektywa 89/391/EEC z dnia 12 czerwca 1989 r. w sprawie wprowadzenia środków w celu poprawy bezpieczeństwa i zdrowia pracowników w miejscu pracy. Art. 6.2. wprowadza zasady ogólne dotyczące zapobiegania zagrożeniom
• Rozporządzenie Ministra Energii z dnia 8 czerwca 2021 r. w sprawie bezpieczeństwa i higieny pracy przy urządzeniach energetycznych (Dz.U. z 2021 Poz. 1210).
• PN-EN 50110-1:2023 Eksploatacja urządzeń elektrycznych – Część 1: Wymagania ogólne

Na świecie opracowano szereg norm i standardów dotyczących ochrony przed zagrożeniem łukiem elektrycznym:

• IEC 61482-2 Live working – Protective clothing against the thermal hazards of an electric arc – Part 2: Requirements
• IEC 61482-1-1 Prace pod napięciem — Odzież ochronna przed zagrożeniami termicznymi
  spowodowanymi łukiem elektrycznym — Część 1-1: Metody badań — Metoda 1 — Określanie
  parametrów łuku (ATPV, EBT50, ELIM) dla materiałów trudnopalnych na ubrania
• NFPA 70E Handbook for Electrical Safety in the Workplace (wydanie 2024)
• IEEE 1584-2018 IEEE Guide for Performing Arc-Flash Hazard Calculations
• ISSA Guide Guideline for the selection of personal protective equipment when exposed to the thermal effects of an electric fault arc (2011)
• DGUV 203-077 Thermal hazards due to electric fault arcing Guide for the selecting personal protective equipment (2021)

W kontekście magazynów energii szczególnie istotne oraz stanowiące przydatne źródło wiedzy są grupy norm:

Europa / IEC:

• IEC 62933 (seria)Electrical Energy Storage (EES) systems – Series of standards (np. IEC 62933-1-1:2018 – Terminology; IEC 62933-5-2 – Safety requirements)
• IEC 62619:2022Secondary cells and batteries containing alkaline or other non-acid electrolytes – Safety requirements for secondary lithium cells and batteries, for use in industrial applications
• IEC 62485 (seria)Safety requirements for secondary batteries and battery installations
  (np. IEC 62485-2:2018 – Stationary batteries)

USA:

• NFPA 855:2023Standard for the Installation of Stationary Energy Storage Systems
• UL 9540Energy Storage Systems and Equipment
• UL 9540ATest Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems

Chiny:

• GB/T 36276-2018Electrochemical Energy Storage System – Lithium-ion Battery Technical Specification
• GB/T 34131-2023 (aktualizowana wersja)Technical Specification for Electrochemical Energy Storage Power Station
• NB/T33015(seria) Technical standards for electrochemical energy storage systems in power applications
• NB/T33004 Technical specification for grid-connected operation of electrochemical energy storage systems

Obszar	Europa / IEC	USA	Chiny
Zakres ogólny systemów BESS	IEC 62933 – Electrical Energy Storage Systems (EES)	UL 9540 – Energy Storage Systems and Equipment	GB/T 34131 – Technical Specification for Electrochemical Energy Storage Power Station
Bezpieczeństwo baterii (ogniwa i moduły)	IEC 62619 – Safety requirements for lithium batteries (industrial)	UL 1973 – Batteries for Use in Stationary Applications	GB/T 36276 – Lithium-ion Battery Technical Specification
Instalacja i integracja systemu	IEC 62485 – Battery installations	NFPA 855 – Installation of Energy Storage Systems	NB/T 33015 – Energy storage system technical requirements
Thermal runaway / testy pożarowe	IEC 62933-5-2 – Safety requirements (system level)	UL 9540A – Thermal Runaway Fire Propagation Test	GB/T (częściowo ujęte w testach systemowych)
Bezpieczeństwo eksploatacji (BHP)	PN-EN 50110-1 – Operation of electrical installations	NFPA 70E – Electrical Safety in the Workplace	GB 26860 – Safety work regulations for electric power industry
Łuk elektryczny (Arc Flash)	IEC 61482 – Arc flash protective clothing	IEEE 1584 – Arc-Flash Hazard Calculations + NFPA 70E	Brak dedykowanego standardu – stosowane podejścia pośrednie

W celu zapewnienia odpowiedniego poziomu bezpieczeństwa prawo w Polsce wymaga od nas szeregu instrukcji i procedur. Dotyczą one także instalacji magazynów energii:

• IOBP – Instrukcja Organizacji Bezpiecznej Pracy
• IEUEE – Instrukcja Eksploatacji Urządzeń Elektroenergetycznych
• IRiESD – Instrukcja Ruchu i Eksploatacji Sieci Dystrybucyjnej ( dla OSDn)
• Instrukcje stanowiskowe i BHP
• PPN – Procedura Prac Pod Napięciem przy urządzeniach elektroenergetycznych ( jeśli wymagana)

Zarządzanie ryzykiem w eksploatacji BESS

Skuteczne zarządzanie ryzykiem związanym z łukiem elektrycznym wymaga systematycznego podejścia, obejmującego następujące etapy:

• Ocenę zagrożenie od łuku elektrycznego
• Ocenę zagrożenia porażeniem prądem
• Ocenę stanu aparatury i instalacji
• Wstępny dobór wymaganych ŚÓI
• Ocenę ryzyka oraz dobór wymaganych śoi dla wykonywanych prac

Pierwszy etap procesu zarządzania ryzykiem polega na identyfikacji potencjalnych miejsc, w których może wystąpić zagrożenie łukiem elektrycznym. Daje nam to możliwość :

• określenie poziomu energii łuku elektrycznego
• strefy oddziaływania łuku elektrycznego (ang.Arc Flash Boundary)
• dalszych działań i rekomendacji

Po zidentyfikowaniu poziomu zagrożeń, należy ocenić ryzyko zagrożeni porażeniem co mocno zależne jest od konstrukcji instalacji oraz wykonywanych prac np. poprzez:

• określenie napieć
• określenie wykonywanych prac w pobliżu napięcia
• określenie prac wykonywanych pod napięciem

Następnie poprzez oszacowanie prawdopodobieństwa wystąpienia zagrożeń elektrycznych dla
poszczególnych czynności oraz prac eksploatacyjnych i możemy dostosować stosowanie do:

• poziomu zagrożenia
• ekspozycji na to zagrożenie
• kondycji i stanu aparatury
• wykonywanych prac

Takie podejście opracowane przez MR Power Systems w formie metody „Uproszczonego doboru oraz oceny ryzyka wykonywanych prac” z ang. (Simplified Task Based PPE Risk Matrix ) pozwala na kontrolowanie stosowanych podczas prac przy urządzeniach elektroenergetycznych.

Skuteczne zarządzanie ryzykiem wymaga podejścia systemowego które zaczyna się od identyfikacji i określenia zagrożeń. W dalszych krokach naturalnie chcemy kontrolować oraz ograniczać ekspozycję na występujące zagrożenia. Tutaj z pomocą przychodzi Hierarchia Kontroli z standardu NFPA 70E-2024 obejmująca kolejność działań od najbardziej efektywnych do najmniej:

• eliminacja zagrożenia,
• redukcja energii,
• środki techniczne,
• świadomość i szkolenia
• rozwiązania administracyjne
• środki ochrony indywidualnej.

Studium przypadku: Victoria Big Battery

Jednym z najbardziej znanych zdarzeń związanych z magazynami energii był pożar instalacji Victoria Big Battery (300 MW / 450 MWh) w Australii w 2021 roku. Zdarzenie miało miejsce podczas testów odbiorczych systemu i stanowi istotny przykład ryzyka charakterystycznego dla wielkoskalowych systemów BESS.

Bezpośrednią przyczyną zdarzenia było wewnętrzne uszkodzenie jednego z modułów bateryjnych. Doszło do utraty szczelności płynu chłodzącego a następnie do zwarcia, które to doprowadziło do lokalnego przegrzania, a następnie inicjacji zjawiska thermal runaway. W wyniku utraty kontroli nad bilansem cieplnym doszło do rozprzestrzenienia się zjawiska na sąsiednie moduły w obrębie kontenera.

Pomimo zastosowanych systemów zabezpieczeń, takich jak systemy detekcji oraz środki gaśnicze, zdarzenie doprowadziło do długotrwałego pożaru, który trwał kilka dni. W trakcie zdarzenia zaobserwowano emisję gazów oraz intensywne oddziaływanie cieplne, co wymusiło wyznaczenie strefy bezpieczeństwa wokół instalacji. Analiza zdarzenia wskazuje na kilka kluczowych wniosków:

• inicjacja zdarzenia może nastąpić na poziomie pojedynczego modułu,
• thermal runaway ma charakter propagacyjny w obrębie kontenera,
• standardowe systemy gaszenia mogą być niewystarczające do zatrzymania procesu, ale
  pozwalają ograniczać skalę pożaru i jego rozprzestrzeniania
• kluczowe znaczenie ma wczesna detekcja oraz separacja modułów,
• projektowanie systemów BESS powinno uwzględniać scenariusze eskalacyjne, a nie tylko
  pojedyncze awarie.

Przypadek Tesla Big Battery pokazuje, że zagrożenia w magazynach energii mają charakter systemowy i wymagają podejścia obejmującego zarówno projektowanie, jak i eksploatację instalacji.

Podsumowanie

Magazyny energii wprowadzają nowy poziom złożoności zagrożeń elektroenergetycznych, wynikający z połączenia zwarć w obwodach DC, trudności w detekcji łuku elektrycznego, napięć powyżej 1000 VDC oraz ryzyka eskalacji zdarzeń do poziomu utraty bilansu cieplnego ogniw. Czynniki te powodują, że klasyczne podejście do bezpieczeństwa instalacji elektrycznych jest niewystarczające.

Zapewnienie bezpiecznej eksploatacji wymaga zintegrowanego podejścia obejmującego etap projektowania, eksploatacji instalacji oraz analizę zagrożeń i ryzyka. Ogólne traktowanie kontenerowych wersji magazynów energii bardziej jako produktów a nie jako instalacji stawia wyzwania w zakresie prowadzenia eksploatacji.

What Is Arc Flash and Why Is It Dangerous?

Let’s be honest: the risk of arc flash is still widely underestimated or misunderstood. When people hear the term electrical hazard, they often think only of electric shock. While electric shock
is undeniably dangerous, arc flash represents a completely different—
and often more devastating—threat. Unlike shock hazards, an arc flash
can release an enormous amount of energy in a split second, exposing
workers to extreme heat, explosive pressure, and molten metal. For anyone
working in the electrical industry, electrical maintenance, electrical
safety, or related fields, misunderstanding or overlooking the danger
of arc flash can have severe or even fatal consequences.

Electrical hazards are present in our daily lives, so it’s crucial to
be aware of them and take the necessary precautions to ensure we get
home safely from work.

The aim of this article is to explain how arc flash risk assessment
process looks like, from the initial contact to installing label on the
electrical panel door. But before we get into the process, let’s make
sure everyone understands what it’s all about.

Electrical Hazards vs Electrical Risk – Key Differences

These terms may sound similar, but for those who regularly work in the
electrical sector, it’s essential to know the definition. An electrical hazard is the source of the potential to cause harm, for example, damaged equipment that could cause a short circuit or an arc flash. On the other hand, an electrical risk is the likelihood and severity of
harm when a person is exposed to an electrical hazard.

Types of Electrical Hazards in the Workplace

When it comes to electrical hazards, the list is longer than we think.
Below are some examples of electrical hazards:

• Electric shock
• Arc flash hazard
• Arc blast
• Electrostatic discharge
• Electrical fires
• Electromagnetic field exposure
• Explosions in Ex areas
• Burns from hot surfaces of energized components
• Induced voltage
• Battery fires and explosions

Arc Flash: Real Risks, Real Costs

Most of the safety training focuses on shock hazards. Arc flash often gets only a slide,
maybe a warning label without important information, sometimes just a sticker for electric shock, and then everyone moves on. That’s a problem—because in terms of raw destructive potential, arc flash is in a completely different category.

Here are some numbers that tend to attract people’s attention:

An arc flash is not just an electrical fault but a violent arc flash phenomenon—a rapid, uncontrolled release of energy that resembles an explosion more than a typical electrical hazard. In milliseconds, temperatures above 19,000 °C, roughly 15 times hotter than volcanic
magma, can vaporize copper and force it to expand tens of thousands of times its original volume.

This sudden expansion generates powerful pressure waves capable of knocking workers to the ground and hurling molten metal at extreme speeds, while intense thermal radiation causes severe burns without direct contact. Blinding light, deafening noise,
and clouds of superheated gases and metal vapors further compound the danger. Unlike electric shock, proximity alone is enough to underestimate this phenomenon means overlooking one of the most destructive hazards in electrical work.

And the costs aren’t just human. A few real-world examples

• OVH SBG1 — arcing fault in a UPS battery room: €105 million loss
• Ocado warehouse, Andover UK — battery charger fault: £110 million damage + £132k fire-fighting costs
• Notre-Dame Cathedral — officially attributed to an electrical fault: €552 million reconstruction cost

The point isn’t to terrify anyone. It’s to establish that this is worth
doing properly.

Hierarchy of Controls in Electrical Safety

Hierarchy of Controls is a safety framework used to reduce or eliminate exposure to hazards in the workplace. It ranks control measures from the most effective to the least effective, helping organizations prioritize solutions that provide the highest level of protection.

Working from most effective to least effective

1. Identification: We could say that the first step is to identify the risks in the workplace. Once electrical hazards are recognized, the next step is to reduce or eliminate them through engineering controls. However, personal protective equipment is still mandatory. The question is how to correctly understand and apply this process in the workplace.
2. Elimination: No live work. LOTO. Arc quenching devices. If you can de-energize it, de-energize it. This is always the preferred option.
3. Substitution: Lower operating voltage. Arc-resistant switchgear. If you can change the system to reduce the inherent hazard, do it at design stage.
4. Engineering Controls: Physical barriers. Remote operation. Isolating people from the hazard spatially. Things that don’t depend on human behavior to work.
5. Awareness: Arc flash labels. Training. People need to know the hazard exists and understand what the labels mean. This is necessary but not sufficient on its own.
6. Administrative Controls: Electrical safety plans. Work instructions. Written procedures for how tasks get done safely.
7. PPE: The correct arc-rated clothing and equipment for the calculated incident energy. Essential, but it only protects the person already exposed to the hazard.

A good arc flash study informs all of these levels, not just the PPE selection.

In conclusion, when an employer implements all elements of the Hierarchy of Controls, the level of risk can be significantly reduced or even eliminated. As a result, the tasks performed by employees transition from relying on the least effective protective measures to the most effective and safest controls, leading to a substantially safer work environment.

How is it understood in the workplace?

In practice, many workplaces are familiar with PPE and administrative controls because they are easier to implement. However, higher-level controls such as elimination, substitution, and engineering controls are often underestimated or overlooked due to cost, design constraints, or lack of early planning.

Do people know about it?

While the Hierarchy of Controls is widely recognized in safety standards and professional guidance, not everyone truly understands or applies it correctly. In many cases, it is treated as a theoretical concept rather than a practical decision-making tool. Improving awareness and
application of the hierarchy is essential for managing high-energy hazards such as arc flash effectively.

Key Arc Flash Standards (NFPA 70E, IEEE 1584, OSHA)

Regarding arc flash performance, it is necessary to be familiar with and apply the relevant standards; the most important ones are listed below:

Standard	Description
NFPA 70E (2024)	Standard for Electrical Safety in the Workplace
IEEE 1584-2018	Guide for Performing Arc-Flash Hazard Calculations
IEEE 1584.1-2013	Guide for the Specification of Arc-Flash Hazard Calculations
CSA Z462-2024	Workplace Electrical Safety
EPRI TR-2011	Arc Flash Hazard Analysis Methodology
OSHA 1910.269 Appendix E	Protection From Flames and Electric Arcs
DGUV 203-077	Selection of Personal Protective Equipment for Electrical Arc Hazards

Supporting standards for the short-circuit side: IEC 60909 (general), IEC 61363 (marine and offshore). ANSI, IEEE, EN, BS standards as appropriate to the system being studied.

It is important to clarify that each country has its own standards. In general, some approach limits and protection zone requirements may change according to national regulations; however, the calculation methodology is usually the same as, or based on, IEEE 1584-2018.

Step-by-Step Arc Flash Risk Assessment Process

Here is how a proper arc flash risk assessment gets done.

Step 1: Customer meeting:

Before initiating any analysis or field visit, it is essential to clearly define and fully understand the project scope. This requires close collaboration with the client to determine the project size, identify the applicable standards, and collect all critical information necessary
to prepare an accurate and effective offer.

Step 2: Data Collection:

Before conducting an on‑site visit for data collection, all available technical information should be reviewed, and the data‑collection format prepared. During the field visit, relevant data is collected accurately, and a safety inspection is carried out. The findings are then documented in a site report that includes observations, analysis, and safety recommendations aimed at improving workplace safety.

Step 3: System Modelling:

Develop a digital twin of the electrical network using specialized software that accurately reflects the actual installed system. The electrical model shall be created with comprehensive and precise details to ensure it faithfully represents the real-world configuration, equipment
characteristics, and operating conditions.

Step 4: Electrical Analysis Calculations.

Performance an Electrical Analysis calculations based in all standards:

• Short Circuit Analysis. IEC 60909 /ANSI
• Short Circuit Equipment Evaluation
• Selectivity Analysis to find protection issues for exiting situation and provide recommendations for improvements for future adjustments
• Arc Flash Analysis – for existing situation acc. IEEE1584 -2018 / sometimes DGUV203-077, provide recommendations for improvements for future adjustments.

Step 5: Report:

The final report includes all results, analysis tables for existing and recommended situations, different scenarios configuration, recommendations, modeling data, single‑line diagrams, and equipment labeling information, compiled and delivered in appropriate formats such as Word, PDF, and Excel.

Step 6: Customer Meeting:

It is essential to hold a meeting with the client to review the report results, discuss identified issues within the electrical installation, and present the proposed recommendations developed in accordance with the Hierarchy of Controls.

Step 7: Training:

Provide technical training on arc-flash hazards, preferably conducted on-site, with online delivery as an alternative. The training covers hazard identification, arc-flash warning labels, proper selection and use of personal protective equipment (PPE), and methods to reduce or eliminate risks through engineering controls, in accordance with the report findings.

Step 8: Final & follow up:

Overall, periodic revisions should be carried out, with results updated at least every five years or following any significant modifications to the electrical system. This process may include retraining workers and updating or replacing equipment warning labels as necessary.

Every year, engineers and technicians are electrocuted — not during high-voltage insulation testing, but after it. The equipment looks safe. The voltage meter reads zero. But inside the insulation, lethal charge is still quietly stored and the dangerous voltage is rebuilding. This post explains why, and how a new technology from Megger called RE>Act is making HV DC insulation testing safer and faster.

MR Power Systems  ·  Based on presentation by Dr Stan Zurek, Megger 

INTRODUCTION

Picture this: a maintenance engineer has just finished a high-voltage DC insulation test on a large motor. The test instrument shows the voltage has discharged to zero, and the operator even used independently a HV discharge stick to ensure that the voltage is indeed discharged. A few minutes later his colleague reaches in to reconnect the motor terminal — and is hit by a shock of several hundred volts. The equipment “looked” safe. But inside the insulation, a hidden charge had been slowly rebuilding.

This phenomenon — known as absorption causing recovery voltage — is well documented in several IEEE and IEC standards, yet still misunderstood by the engineers working with HV equipment every day. RE>Act, a new technology from Megger invented by the team: Paul Swinerd, Stan Zurek, Mark Tutton, Clive Taylor, and Mohineet Kaur, was created specifically to make this invisible hazard visible.

First: what is electrical insulation, really?

Every cable, motor or generator winding, transformer coil, bushing, insulator, surge arrester, and circuit breaker contains electrical insulation — the material that prevents current from flowing where it shouldn’t. Without insulation, high-voltage electricity cannot be safely contained or controlled.

But insulation is not just a passive barrier. From an electrical engineering perspective, insulation behaves like a complex circuit made up of three components working simultaneously:

Component	What it does
Resistance (R)	The classic insulation property — a high resistance means very little current leaks through. This is what insulation resistance (IR) tests measure in MΩ, GΩ, or TΩ.
Capacitance (C)	The insulation stores electrical charge, like a capacitor. This charge builds up quickly during a test and also discharges quickly. It is always dangerous when not discharged.
Absorption (A)	The most misunderstood component. Polarisation of molecules within the insulation material causes charge to be absorbed slowly — and released slowly. This is the hidden hazard.

This three-part model — known as the “equivalent Debye model” — is the key to understanding why HV testing is dangerous even after the voltage source is switched off.

The hidden hazard: what happens after the test?

High voltage is applied to a piece of electrical equipment during the test. The capacitive component charges quickly and discharges quickly when the test ends — this is the part that most discharge procedures are designed to handle, and it is easy to understand.

But the absorption component is different. It charges slowly — and it discharges slowly. Worse still, even after the capacitive charge has been discharged to zero volts, the absorption charge begins to release itself — and this release creates a recovery voltage: the terminal voltage rises again, from zero, back up to potentially dangerous levels. All by itself.

Without any external source. So the capacitance becomes charged again, and charged capacitance is always dangerous.

The confusion is made worse by how standards describe this. IEEE 43-2013 defines the absorption current as one that decays “to nearly zero” — but “nearly zero” reading will be displayed differently by various equipment. Is 0.001 mA nearly zero?

To same people it may, but in reality it is certainly not. At high voltages, this small current can still transfer a lethal charge, from the absorption branch to the capacitive branch. The gap between laboratory theory and workshop reality has safety implications.

What do the standards actually say?

Both IEEE 43 and IEEE 95 — the two main standards governing HV DC insulation testing for rotating machines — acknowledge the hazard, but offer surprisingly vague guidance on how long to wait before touching the equipment.

Read those carefully. The standards say: wait at least 2 hours. Or 4 times the test duration. And you can’t accelerate it. In practice, this means engineers face a choice: wait for hours (with no confirmation that it’s actually safe), or take a risk of confirming that the dangerous voltage is absent. But the standards don’t explain how to do that safely.

In busy maintenance environments, the pressure to get equipment back online is substantial. The lack of real-time feedback — any way to actually see whether the discharge is complete — is exactly the gap that RE>Act was designed to fill.

Introducing RE>Act — see the invisible

RE>Act stands for RE-Absorption Current Test. It’s a new inventive technology (patent applied for) integrated into the new Megger S1 and MIT 5–10–15 kV insulation testers.

The core idea is elegant: instead of disconnecting the equipment and hoping the discharge is complete, RE>Act connects a low-impedance ammeter through a discharge resistor while monitoring the actual discharge current in real time. Both the capacitive discharge and — crucially — the absorption discharge are measured and displayed as they happen.

The operator can now see the real discharge progress in real time, so the guessing is eliminated. So this “dual discharge” process can be now observed in real time by the operator.

How it works — step by step

The RE>Act display shows additional information. At the bottom it is the real-time measured current during absorption discharge. In the middle it is the voltage of the next test as selected on the equipment. The actual voltage is zero (the insulation remain short-circuited), so the RE>Act test is inherently safe by itself. However, the information about the next test voltage and the real current is used for estimation of the usable measurement range for the next test on the same insulation.

If the next expected result is in the accurate range then the next test can be started even without waiting for the full discharge. But if the next result is likely to fall in the blocked range, then longer discharge is necessary, otherwise an unknown amount of measurement error will occur. This helps in avoiding condemning good insulation as bad, or worse still approving bad insulation as good.

Real-world results

RE>Act was tested on multiple types of equipment. Even on a relatively small 50 kVA oil-filled transformer, the discharge behaviour was clearly visualised and the absorption component took significantly longer to dissipate than the capacitive component. The absorption current was above 1 nA even 20 min after the test was finished. On a 90-metre long HV cable (20 kV rated, 16 nF capacitance), the cable remained unsafe for over 25 min after the capacitive voltage had reached zero — precisely as IEEE 95 warns, but now visible and quantifiable in real time.

Operators who used RE>Act on HV motors were able to significantly improve productivity, because they could significantly reduce the 2 h blind waiting time. But more importantly – they were able to eliminate the invisible danger.

PI Predictor — faster testing without compromising safety

RE>Act solves the safety side of the equation. But the productivity is also improved, almost as an effortless byproduct of using this feature.

The Polarisation Index (PI) is a standard diagnostic test that compares the insulation resistance at 10 min and 1 min. A healthy insulation shows increasing resistance over time (good absorption behaviour). But waiting 10 min for every test — and then waiting another 40 min (or even 2 h, depending on the standard) for safe discharge — creates a significant bottleneck in maintenance schedules.

PI Predictor exploits a physical symmetry: shorter polarisation (absorption) means shorter depolarisation (reabsorption). By running a shorter polarisation test and measuring the depolarisation behaviour, the PI Predictor algorithm can predict the 10-minute PI result in typically in just half of the time.

50 min Standard PI test + discharge (10 min charge + 40 min discharge)

14 min With PI Predictor + RE>Act (5 min charge + 9 min discharge)

72% Reduction in total test time — while remaining equally safe and accurate

The test was validated on a 90 kW LV motor. The predicted PI result matched the standard 10-minute result. Total test time: 14 min vs. 50 min. For facilities running dozens of insulation tests per year — on motors, cables, transformers, generators — the productivity gains compound rapidly.

Three benefits that change how HV testing works

Benefit	What it means in practice
Safety	Visualise the complete discharge process — both capacitive and absorption — in real time. Know with certainty when it is safe to touch the equipment, rather than guessing based on a 2-hour waiting rule.
Accuracy	Quantify the correct measurement range before the next test. RE>Act shows not just whether discharge is complete, but the prospective IR range for the next test cycle on the same insulation — eliminating errors due to negative currents.
Productivity	Eliminate unnecessary “blind” discharge time. With PI Predictor, as the total test + discharge time can be reduced by up to 72% while maintaining the same safety margin and diagnostic accuracy.

Why this matters beyond the test lab

HV insulation testing is performed routinely on industrial motors, generators, transformers, and cables — in power stations, manufacturing plants, marine vessels, wind farms, and anywhere else large rotating machines or power distribution equipment is maintained.

The engineers doing this work might be experienced professionals. But experience doesn’t protect you from a hazard you can’t see, and boring routine can be dangerous. Recovery voltage — the insulation recharging itself — is invisible, silent, and can appear minutes or hours after the test ends. The fact that IEEE standards call for 2-hour waiting periods tells you everything about the severity of the risk. And that is with insulation short-circuited. Without short-circuiting the danger can remain for “indefinite” time.

RE>Act doesn’t change the physics. It makes the physics visible. And in safety-critical work, the difference between “I think it’s discharged” and “the instrument confirms it’s discharged” is the difference between risk and certainty.

The Big Picture: Why This Matters

Europe’s electricity grid is under serious strain. Almost every major substation is running at or near its maximum capacity. On top of that, we’re connecting more and more renewable energy sources — solar farms, wind parks — which need new power lines and transformers to bring their electricity into the grid.

To keep up, engineers are adding new lines and transformers to existing infrastructure. But this creates a problem: the safety systems that protect those lines were designed for simpler setups. Now, the setups are getting more complex.

This article explains one key safety system — called Line Differential Protection (or ANSI 87L) — and how it’s being adapted to work in these newer, more complicated configurations.

1. What Is Line Differential Protection?

Think of a power line like a water pipe. If you measure the water going in at one end and the water coming out at the other, they should be equal. If they’re not — some water is leaking somewhere.

Line Differential Protection works the same way with electricity. Sensors called Current Transformers (CTs) measure the current (electricity flow) at both ends of a protected section of line. Under normal conditions, what goes in equals what comes out. If there’s a difference — a fault (like a short circuit or a break in the insulation) — the system detects it and automatically switches off that section to prevent damage or danger.

Why is this important?

Standard Line Differential Protection uses two measurement points (one at each end of the line) and works very well for simple, straight lines. The challenge is: what happens when the line isn’t simple anymore?

2. Three New Challenges

Modern grid development is creating three types of configurations that go beyond the classic straight-line setup:

Challenge	What it is	Main problem
A	A line that splits into a T-shape (three branches)	Three ends to measure, not two
B	A line with a transformer attached at the end	The transformer shifts the signal in ways the sensor must account for
C	A T-shaped line with a transformer in the mix	Both A and B combined — needs four sensors and more complex calculations

3. Challenge A: The T-Shaped Line

What’s the problem?

Imagine a road that splits into three directions. At each road end, you have a sensor. Now, instead of just checking that traffic in equals traffic out at two points, you need to balance three roads at once. That’s what happens with a T-junction in a power line.

With three branches, you need three protection relays (safety devices), all connected to each other by a fiber-optic cable so they can share their measurements in real time.

The hidden complication: cable shields

Modern underground cables are wrapped in a metal shield — a bit like the outer foil on a coaxial TV cable. This shield helps contain the electric field and carries fault current if something goes wrong. The tricky part is how the shield is connected to the ground.

There are three common ways to do this: Solid Bonding (both ends grounded), Mid-Point Connection (only the middle is grounded), and Cross Bonding (the most common in long high-voltage cables, where sections of shield are swapped and grounded in a pattern that nearly cancels out induced currents).

The protection system sees these shield currents too. It needs to know which currents are normal and which signal a real fault. The algorithm has to be configured for the grounding method used in each installation.

4. Challenge B: The Line with a Transformer

Why are transformers being added to existing lines?

A transformer changes the voltage level of electricity — for example, from 30,000 volts (30 kV) down to 20,000 volts (20 kV) — so it can be distributed to homes and businesses. As new areas or renewable energy installations are connected, engineers often attach a new transformer at the end of an existing cable rather than building a completely new substation.

Two things that make this tricky

1. Phase shift: Transformers don’t just change voltage — they also shift the timing of the electrical wave. The protection relay on one side sees the current slightly out of step with the relay on the other side. Without correction, this looks like a constant fault. The relay must be programmed to apply the right correction factor.

2. The tap changer: Most transformers can fine-tune their output voltage using an automatic mechanism called an On-Load Tap Changer (OLTC). Each step changes the current ratio by about 1–2%. The protection settings must cover the full range of tap positions while still being sensitive enough to catch real faults.

Where to put the sensors?

5. Challenge C: T-Junction + Transformer

This is the most complex case — a T-shaped line where one branch connects to a transformer. You now need four protection relays, all communicating with each other.

The system must handle everything from Challenges A and B at the same time:

• Balancing currents across three cable branches
• Correcting for the transformer’s phase shift
• Staying stable across all tap changer positions
• Correctly interpreting cable shield currents

It’s a lot — but modern protection hardware and software can handle it, provided it’s set up correctly.

6. Does It Actually Work? Simulation Results

Before deploying these systems on a real power grid, engineers test them in computer simulations (MATLAB/Simulink). The key test for each scenario: does the protection correctly trip (switch off) when there’s a fault inside the protected zone, and correctly stay on when the fault is outside?

Challenge B: Fault outside the protected zone

Challenge B: Fault inside the cable

Challenge B: Fault at transformer input terminals

Challenge A: Fault outside the T-cable area

Challenge A: Fault inside the T-cable area

Challenge C: Summary result

In every case, the extended ANSI 87L algorithm correctly identified whether the fault was inside or outside the protection zone. No false alarms, no missed faults.

7. Key Lessons

The basic principle still works — but needs adaptation

The ‘what goes in must equal what comes out’ principle is still valid for all three configurations. What changes is the implementation: more sensors, more communication between devices, and more sophisticated calculations.

Sensor placement is critical

You can’t just put the current sensors anywhere convenient. The rule is straightforward: sensors must be placed at every point where current can enter or leave the protected zone. Getting this wrong doesn’t just reduce effectiveness — it can make the protection completely blind to certain types of faults.

Cable shield currents are useful, not a nuisance

Engineers sometimes see shield currents as an unwanted complication. In reality, they’re a valuable signal. During an internal cable fault, shield currents spike to levels that are easy to distinguish from normal operation. A well-designed system uses this as an extra early-warning indicator.

The tap changer must be factored in from the start

If a transformer with an automatic tap changer is included in the protected zone, the protection settings must cover the full range of tap positions. A setting that works fine at mid-range may cause false trips at the extremes. The safest approach is to verify this through simulation before the system goes live.

8. Conclusion

Line Differential Protection is one of the most reliable safety tools in the power engineer’s toolkit — it’s fast, accurate, and robust. These qualities don’t disappear as power grids become more complex, but they do require more careful engineering to preserve.

The three challenges described in this article reflect real trends: more underground cable, more renewable energy connections, and more complex layouts driven by the need to expand grids without always building entirely new infrastructure.

The good news is that all three configurations can be safely and reliably protected with modern systems — as long as engineers follow these principles:

• Define the protection zone clearly and put sensors at every boundary point.
• Account for the cable shield grounding method in the protection algorithm.
• Apply the correct correction for the transformer’s phase shift.
• Design the settings to remain stable across the full tap changer range.
• Use simulation to verify everything before commissioning.

What Is Arc Flash? 

Before diving into calculations, it helps to be precise about what arc flash is — and how it differs from a short circuit. 

Short circuit vs arc fault 

A short circuit (bolted fault) is a 1, 2 or 3-phase fault where impedance at the fault location is assumed to be zero or not, depends on calculations we need. It produces the theoretically maximum fault current and determines equipment interrupting ratings.  

An arc fault is different. It is almost any fault that is not a short circuit fault — one with electrical arc formed (impedance) in the fault path, sometimes intermittent. The impedance of arc causes arc current to be lower than bolted fault value, but the arc generates an enormous release of heat and mechanical stress on the installation and personnel nearby. 

Definition

Arc Flash Hazard (NFPA 70E-2024): A source of possible injury or damage to health associated with the release of energy caused by an electric arc. Risk increases when energized conductors are accessible during maintenance or operation.

LV vs MV — which is worse? 

A common misconception is that high-voltage systems are automatically more dangerous. At medium voltage (10 kV), arcing current stays close to the bolted fault current level. At low voltage (400 V) the ratio drops steeply: at 50 kA bolted fault current, the arcing current may be only 37-50% of the bolted value so even down to 20kA in this example. 

This means that at low voltage, with very high available fault currents, arc energy can reach extreme levels. The answer to ‘LV or MV worse?’ is: it depends on the installation. Without calculation, you do not know. 

Do you know?

Where is the worst location for short-circuit stress in a typical MV/LV substation?

1. MV switchgear 15 kV
2. transformer 15/0.4 kV
3. main 400 V circuit breaker?

Answer: the main LV CB (incoming panel) is almost always the worst — it sees full transformer fault current with the longest possible clearing time.

Standards — Knowing What You Are Working With 

Arc flash safety uses a combination of standards. Understanding which apply to your situation — and how they interact — is a prerequisite for any study. 

Most commonly used (EU and global):

• IEEE 1584-2018 — primary standard for arc flash incident energy calculations (AC, 208 V to 15 kV). 
• IEEE 1584.1-2023 — requirements for performing arc flash studies. 
• NFPA 70E-2024 or local version— primary reference for PPE selection, working distances, and electrical safety programme structure. 
• IEC 61482-1-1 — open arc test for PPE (ELIM rating in cal/cm²), most relevant in Europe. 
• CSA Z462-2024 — Canadian equivalent of NFPA 70E, used in some international projects.

Less common but technically significant:

• DGUV-I 203-077 — German guide using IEC 60909 short-circuit data; applies a 1-second maximum duration time rule (vs unlimited or 2 seconds in NFPA 70E — a key difference that significantly affects results). 
• IEC 61482-1-2 — box test PPE (APC1 or APC2 classes) used to select PPE 

Common practical approach in EU: IEEE 1584-2018 for calculation + NFPA 70E-2024 for PPE selection + IEC 61482-1-1 for PPE testing standard. The difference between DGUV203-077 and IEEE1584 is a critical and must be understood before choosing your methodology. Its not simple change 

Arc Flash Boundary and Labels 

Hazard zones

Arc flash hazard zones are distinct from shock hazard zones. The arc flash boundary is defined by energy: the distance at which incident energy decays to 1.2 cal/cm² — the onset of a second-degree burn on bare skin. In practice the arc flash boundary is often significantly larger than shock hazard zones. 

Line side vs bus side

The upstream (line) side of an incoming circuit breaker is typically much more dangerous than the downstream (bus) side, because it is protected by the upstream device — which may have, a much longer clearing time. A real example: line side 37.1 cal/cm², bus side 2.85 cal/cm² on the same panel. Both need separate labels and separate PPE assessments.

Arc flash label content (per IEEE 1584 / NFPA 70E) 

A compliant label must include:  nominal voltage level, incident energy (cal/cm²) at working distance, arc flash boundary, required PPE level and/or minimum arc rating or PPE Category   

And optionally but very useful:  location identifier, insulation glove class, shock hazard zones, line side or bus side, date of analysis, and the standard used. 

The Hierarchy of Controls — Design First, PPE Last 

The correct approach follows the classical hierarchy: eliminate first, then substitute, then engineering controls, then administrative controls, then PPE. PPE is the last resort. 

The problem becomes stark at extreme energies. No PPE exists at 200 cal/cm² or above. So before anyone opens a PPE catalogue, the energy must be brought down to a level where selection is even possible. 

Five key mitigation tools 

Protection setting optimisation: cheapest and most technically demanding. Reduce fault clearing times while preserving selectivity. Longer tripping times improve selectivity but increase arc energy — getting both right requires skilled engineering, but can transform the numbers without touching hardware. 

Optical arc detection: light sensors that react to an arc flash far faster than overcurrent protection. Response time is decoupled from current-time settings. 

Arc quenching systems: deliberately create a short circuit inside the panel, collapsing arc voltage to near zero. Results are dramatic: incident energy can drop from 100 cal/cm² to 0.1 cal/cm². 

Maintenance mode : temporarily overrides protection settings with faster parameters for the duration of work. A lockout/tagout procedure must prevent deactivation during work. 

Covers and separation forms: simplest and cheapest mitigation, most frequently overlooked. Easiest way to reduce likelihood.

Optimizing Protection Settings — A Real Project 

The following case study shows what is achievable purely through engineering, without replacing any switchgear. Starting installation: MV/LV transformer substation ,a small part of much bigger electrical model. 

The entire improvement was achieved without replacing switchgear and withou hundred thousands to t multi-million investment. Purely through engineering: reprogramming the MV relay, reviewing LV trip units, activating maintenance mode, and adding optical arc detection. 

At 90 cal/cm², PPE selection is irrelevant — there is no practica PPE to select, at least in Europe. At under 4 cal/cm², the hazard is fully manageable with standard arc-rated PPE. Same installation. Different settings. Dramatically different hazard profile. 

IEEE 1584:2018 — The Calculation Framework 

IEEE 1584:2018 equation application range: 

voltages 208 V to 15 kV; 50/60 Hz;  

bolted fault currents 500 A to 106 kA (LV) and 200 A to 65 kA (MV);  

electrode gaps 6.35 mm to 254 mm.  

Below 240 V and at fault currents below 2000 A, a three-phase arc is unlikely to sustain — which doesn’t make the system safe, but limits calculation applicability. 

Step-by-step procedure:

1. Select electrode configuration (VCB, VCBB, HCB, HOA, or VOA). HCB — horizontal electrodes facing the worker — is typically the worst case. 

2. Calculate intermediate arcing current at 600 V, 2700 V and 14300 V reference voltages using the polynomial equations in Table 1. 

3. Correct for actual system voltage — e.g. interpolate from the 600 V equation down to 415 V using Equation 25. 

4. Apply variation factor (VarCf) — actual arcing current may be lower than calculated. If it falls on the flat part of a time-current curve, tripping time and incident energy increase dramatically. 

5. Calculate enclosure correction factor (CF) — compares actual enclosure dimensions to the standard’s reference test dimensions. 

6. Calculate incident energy using the interpolated arcing current, clearing time, and CF. 

7. Calculate arc flash boundary — distance at which energy decays to 1.2 cal/cm². 

Worked example: 2 MVA transformer at 415 V 

Why calculation software is not optional at scale 

In softwares like ETAP, SKM, CYME and so on  modifying one element triggers automatic recalculation of the entire model. In a spreadsheet, the same update can mean days of work per revision. The practical consequence: people stop updating their calculations — and an outdated arc flash study is more dangerous than no study at all. 

NOT Fun Fact: Before you order the switchgear — check, calculate, verify. Once equipment is installed and the budget is spent, the money for upgrades are gone. 

Data Quality — The Make-or-Break Factor 

The most important observation from any arc flash study has nothing to do with calculations. It concerns the data that feeds them. 

The single-line diagram is the foundation of every arc flash study. In the real world it is frequently ten to twenty years out of date, inconsistent with actual field configuration, and ambiguous — multiple transformers labelled ‘Tr1’, multiple breakers labelled ‘Q1’. 

In one project, the model had to be started from satellite imagery. Getting usable data from clients can itself be a major challenge. 

Knowing what to do with the results — adjusting settings without compromising protection coordination, proposing solutions that are actually implementable — is where the real expertise lies. 

Conclusion

Arc flash safety is not about buying PPE randomly. It is a multi-layered system that begins at the design stage, runs through hazard identification, engineering solutions, electrical safety plans, and operating procedures, maintenance plans — and only then arrives at PPE selection as the final line of defence.

IEEE 1584:2018 provides a solid calculation framework, but it only works with reliable input data, a well-constructed network model, and engineering judgement. Calculation software does not replace knowledge — but without it, keeping arc flash studies current through every design revision is practically impossible.

PPE is the last line of defence, not the first. When incident energy exceeds 40 cal/cm², engineering mitigation must come before any PPE discussion. Protection settings optimisation alone can reduce incident energy by 50–80% — at zero hardware cost. The worst location in a typical MV/LV substation is almost always the main LV incoming panel, where full transformer fault current meets the longest clearing time.

Two things are worth remembering above all: outdated arc flash studies are worse than none, because they create false security. And data collection accounts for 30–40% of the total study effort — garbage in, garbage out. 

Things to check

• Check how you selected PPE in the first place? 
• Do you know your arc flash hazard incident energy ? 
• Do you solve problems with PPE or as written above? 
• Do you have locations above 40 cal/cm2 that can be improved ? 

“`

Arc Flash Risk Assessment

Risk assessment. What can be done to ensure that it does not become merely a formal obligation – a forgotten sheet in a binder or an exercise in creative table filling? This article is devoted to this issue.

Although the starting point is electrical hazards – in particular the risk of electric arc – the issues discussed are universal. In practice, risk assessment in electrical work is a difficult area to properly address. Is it even possible to capture its specificity in a simple, repeatable, and useful way?

In this article, we will discuss:

•  What is the difference between hazard analysis and risk assessment?

•  What are the consequences of weak processes?

• What can be done differently to make risk assessment actually work.

Hazard analysis and risk assessment – what is the difference?

The terms hazard and risk are often used interchangeably. I have heard many times—and I have to  admit that I have also used—phrases such as “this is a major hazard” or “this is high-risk work.” They sound similar, but in fact they are different concepts.

Based on the approach of ISO 45001, PN-N-18001, and NFPA 70E, we can adopt simplified but very useful definitions:

• Hazard – a source of potential injury or deterioration of health. In electrical work, these include electric arc energy, electric shock, electromagnetic fields, and electrostatic charges.
• Probability – the chance or frequency of a given event occurring within a specified period of time (day, month, year).
• Risk– combination of hazard and probability of its occurrence.

This is most often written in simplified form:
Risk = Hazard × Probability

This is where resistance often arises: “It’s not gambling or poker – why do we need probability?” Ironically, the English word “hazard” means in polish  “gambling.” But let’s leave word games aside.

What hazard and risk mean in practice?

Hazard and risk are inseparably connected, but only by separating them do we gain real practical value.

Example:
The level of hazard from an electric arc is 7.6 cal/cm² (arc flash  incident energy). This is a calculated value and difficult to dispute. However, the probability depends on what activities we perform, under what conditions, and on what equipment. What’s more, not every accident is the result of human error.

To assess this, we need a system: data, criteria, and a tool, such as a risk matrix.

The grey zone of probability

It’s hard to argue about the level of hazard — it’s numerical and measurable.
Probability, however, is a different story. In my experience, this is exactly what creates the so-called grey zone of risk assessment. Data is lacking, and subjective judgment easily leads to manipulating the outcome.

Example:
Voltage measurement on the main busbars of a 415 V / 2000 A switchgear, with an arc flash incident energy ( hazard )of 7.6 cal/cm².

Let’s assume a 3×3 scale:

• Hazard: arc flash – medium (2)

• • Probability: high (3)

Risk = 2 × 3 = 6 

However, it is enough to arbitrarily reduce the probability to 1 for the risk to drop to 2 or 4. The difference is huge – and it may determine whether additional control measures or protective actions will be implemented.

Consequences of incorrect risk assessment

An overly general assessment leads to:

• broad scope for interpretation of results,

• actions that are not applicable to actual risk,

• loss of employee confidence in the entire procedure,

• more serious injuries due to a lack of adequate protection,

• lack of repeatability.

On the other hand, an overly detailed assessment results in:

• mental overload for employees,

• impractical process,

• implementation resistance

• increased time and costs.

How to limit subjectivity?

Risk assessment will never be completely objective – but subjective part can be significantly reduced by:

• initial visual inspection,

• analysis of tasks performed,

• assessment of the technical condition of equipment,

• consideration of human factors,

• decision paths preparation

• PPE pre-selection

The goal should be simple, practical tools, not more procedures “on paper.”

Task-based PPE Selection Matrix – practical example

One such tool is the Task PPE Risk Matrix implemented by MR Power Systems. This is not a universal solution—it was designed for specific requirements and working environments—but it perfectly illustrates a practical approach.

The matrix takes into account, among other things:

• condition of equipment, 

• type of hazards (arc flash, electric shock), 

• list of tasks performed, 

• preselection of PPE, 

• probability assessment, 

• final risk assessment. 

As a result, most of the analytical work has been done in advance by specialists. The employee receives a tool that is ready to use.

How to create an electrical work risk assessment?

The presented model uses several key indicators:

• equipment assessment (condition, inspections, documentation),
• risk assessment (arc flash study, electric shock),
• list of tasks performed (e.g., from the electrical safety plan or operating manuals),
• PPE preselection matrix based on hazard assessment
• risk assessment.
  

What can be done about it?

Condition of equipment:

1.    The device is correctly installed.

2.    The device is properly maintained.

3. The device is adapted to the available short-circuit current.

4. The device is used in accordance with the manufacturer’s documentation or instructions.

5. The device doors are closed and secured.

6. All covers are in place and secured.

7. There are no signs of an impending failure

Task list:

• determining what work will be performed,

• assessing whether the work involves any specific hazard.

Wymagane poziomy ŚOI: 

• preselection of PPE for use on the customer’s premises,

• specification of PPE protecting against electric arc burns,

• minimum PPE requirements (e.g., for subcontractors),

• specification of PPE protecting against electric shock,

• system for selecting and using PPE (e.g., multilayer, all-day, dedicated).

Determining likelihood:

• determination based on data or work analysis,
• assignment in a matrix (e.g., 2×2),
• determination of the impact of equipment condition on probability

Hazard level

It refers to the incident energy level. There are several methods — and at least three common approaches — to determine it:

• Performing detailed arc-flash incident energy calculations (e.g., IEEE 1584, DGUV 203-077, DC calculation models)
• Using table-based approaches (e.g., NFPA 70E, CSA Z462)
• Applying predefined or pre-calculated incident energy values

Each approach has its benefits, but the key requirement is to obtain a dependable estimate of the potential arc-flash hazard. Among these options, the IEEE 1584 calculation method is the most comprehensive and is widely considered the preferred standard.

Example of arc flash pre-calculation

Because each stage carries the risk of error, this approach is suitable only when applied under strict oversight and should not serve as the primary method for determining arc-flash incident energy.

The final result

Ultimately, we obtain a PPE selection matrix for the work to be performed. It takes into account the condition of the switchgear, the type of work performed, exposure to live parts (e.g., unshielded busbars or cable terminals), and the level of risk.

In this form, most of the analytical work has already been done by a specialist team. The tool can be easily verified based on real events or accidents. In the case described, the matrix was prepared for a large group working in service mode (i.e., not on their own installation). The list of tasks has been grouped and simplified to correspond to real situations.

Inherent and residual risk – and the role of the control hierarchy

In classic risk assessment, we always talk about the situation before and after the application of mitigating measures. In the case of the task matrix, this pre-selection has been done in advance.

Here, it is worth referring to the control hierarchy according to NFPA 70E, which clearly shows that PPE is the last line of defense, not the only solution. Technical, organizational, and procedural measures are of key importance.

Two perspectives – one goal

From the perspective of:

• the employer – we implement solutions and eliminate risks,

• the employee – we use the measures provided.

From the perspective of an employer, health and safety department, chief power engineer, or consultant, the process is the opposite of that from the employee’s point of view. First, we analyze how to eliminate or reduce the hazard, and then we expect the implemented solutions to be applied.

In practice, some measures only require technical implementation, while others require acceptance and understanding on the part of the staff. Although resistance to change is natural, solutions whose purpose is clearly communicated work best.

The matrix can be expanded to include a preselection of measures to reduce the risk or probability, which is justified because the employer bears the responsibility and has a decisive influence on the selection of solutions.

In practice, the biggest challenge is not technology, but acceptance of change. My experience shows that resistance is lower when people understand why we are implementing something.

Conclusions

• Probability should be based on data and analysis, not intuition.

• Matrices allow you to clearly define the minimum requirements for PPE.

Summary

The selection of PPE can only be made on the basis of a risk assessment. However, ignoring work procedures, the condition of equipment, and employee experience, it is easy to end up in a situation where we use full protection “always and everywhere.” Paradoxically, a well-designed matrix limits the use of PPE to places where it is really needed—and not where we are simply “afraid” to do something.

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Rising Importance of Electrical Safety in the Workplace 

Electrical safety importance is growing  year after year. It is not only about compliance with standards and regulations, but also about responsibility of electrical engineers, managers, and employers.  Electrical safety awareness is important for production continuity and  safety culture at work. This very issue was the focus of the Electrical Safety Conference Europe 2025 (ESC EU), held on October 23–24 in Cracow. 
The event, organized by MR Power Systems, brought together experts from across Europe — representatives of industry, technical organizations, and  solution suppliers.  

Arc Flash Risk Assessment and Practical Protection Strategies 

Over the course of two days in Cracow, the discussions centered around the most pressing topics in the field: arc flash protection, electric shock risk assessment, the implementation of modern personal protective equipment, and the interpretation of current and emerging European standards. The focus was on practice over theory. 
Experts emphasized that while standards and regulations provide a necessary framework, the true challenge begins with their implementation in the workplace. That is when experience, awareness, and collaboration between engineering, maintenance, and safety departments become crucial. 

Sylwester Linowski & Adrian Ciok, Hubix

Engineering Insights: Arc Flash Hazards Still Underestimated 

Participants agreed that arc flash remains one of the most significant hazards in electrical environments , just after electric shock hazard which is leading electrical hazard. Arc Flash consequences can be catastrophic, while awareness of its risks in many facilities remains insufficient. 
Speakers — including engineers with extensive experience in electrical safety,  electrical systems and safety professionals— highlighted the need for comprehensive risk assessments and the proper selection of PPE, adapted to specific working conditions. 
Presentations also underscored the importance of personnel training, human factors and the creation of procedures that shape a true safety culture within organizations. 

Innovative Electrical Safety Technologies at the Expo Zone 

ESC EU 2025 conference was not limited to technical lectures. The expo area showcased a wide range of innovative solutions — from arc flash detection systems, diagnostic and measurement equipment, to protective clothing and tools which enhance electrical safety. 
Exhibitors and participants had the opportunity to engage directly, exchange experiences, and establish valuable business relationships. For many attendees, networking proved to be one of the most valuable aspects of the event, fostering collaboration between industry, technology providers, and consulting organizations. 

Networking, Regulation Trends, and the Future of Safe Energy Systems  

The atmosphere throughout the conference was both professional and inspiring. 
In informal discussions, attendees reflected on the upcoming changes in European electrical safety regulations, the future of electrical infrastructure, Battery Energy Storage Systems (BESS), PV systems, EV cars and ongoing life electrification. All of this requires proper approach to electrical risk assessments 
There was also much discussion on the growing role of digitalization in monitoring and analysing electrical systems — from smart sensors to integrated digital twin platforms. 

Electrical Safety as a Strategic Priority for Industry   

The Electrical Safety Conference Europe 2025 in Kraków demonstrated that electrical safety today is not an isolated discipline — it is a strategic one. 
It requires awareness, a systemic approach, and collaboration across organizational boundaries. 
Participants left Kraków not only with the latest knowledge and inspiration, but also with a clear view that investing in safety means investing in the future — of both people and the installation.

Gratitude to Sponsors and Partners Supporting Workplace Safety 

The conference would not have been possible without the support of our Partners and Sponsors. 
We extend our sincere thanks to: 
stuckeGROUP, Hubix, TRANEMO Advanced Workwear, DEHN SE, Aktywizacja, Acteq, ArcSwitch, BCA Engineering Group, BSD Bildungs- und Servicezentrum GmbH, EATON, Etap, Grace Technologies, Megger Sp. z o.o., SPIE Energotest, as well as our Technical Partners — ArcelorMittal and the Polish Committee for Electrical Safety SEP. 

Special thanks also go to our Media Partners: 
ATEST Ochrona Pracy, Bezpieczeństwo Pracy. Nauka i Praktyka (CIOP-PIB), CIRE.pl – Energy Market Information Center, INPE, WysokieNapiecie.pl, and ZIAD Bielsko-Biała S.A. 

Electrical Safety Conference Europe – Workplace Electrical Safety & Arc Flash in Europe

Electrical safety is not only a legal requirement or a forced necessity. It is a matter of responsibility for the health and life of employees as well as the continuity of production in every industrial plant. The experts at MR Power Systems know this well, as they have been engaged for years in professional risk analyses, electrical installation audits, and the implementation of comprehensive protective solutions. This is why, as MR Power Systems, we are organizing a unique event dedicated to workplace electrical safety and arc flash hazards in Europe – Electrical Safety Conference Europe 2025 (ESCEU). 

Electrical Safety Conference Europe 2025 23–24 October 2025 |
Premier Kraków Hotel, Adress: Opolska 14a, 31-323 Cracow, Poland

Why ESC EU and why MR Power Systems?  

The idea of the conference was inspired by the popular ESW IEEE (Electrical Safety Workshop) event organized in the United States since the 1990s. Initially, we simply wanted to bring this format to Europe, but during the preparations it became clear that we needed something of our own. An event with an approach tailored to the specifics of the European market and the challenges we face in Europe. MR Power Systems, as an expert in electrical safety and arc flash protection in Europe, took on the challenge of creating a unique conference that would become a platform for sharing experiences, knowledge, and best practices. 
Our goal is not only education, but above all, a real improvement of working conditions, minimizing the risk of accidents, and increasing the awareness of technical and managerial staff in the field of electrical hazards. 

Who is ESC EU for? 

The conference is dedicated to everyone for whom workplace electrical safety is a key element of operations. This includes, among others: 

• Representatives of maintenance departments and people responsible for the operation of electrical installations.
• People managing the operation of electrical installations in industrial plants, utilities, PV, Wind, BESS installations.
• Electrical safety specialists and occupational health and safety specialists.
• Public safety institutions.
• Manufacturers of technical solutions and arc flash protection equipment for electrical safety.
• Specialists, experts, and consultants in the electrical industry.

Conference topics – practice over theory 

At Electrical Safety Conference Europe, we focus above all on practical workplace electrical safety solutions. We will address topics broadly related to electrical safety. This edition emphasizes arc flash hazards and electric shock hazards (risk). We place great importance on the simplicity of knowledge transfer, as we want it to also reach those who are new to the subject. We know how challenging these issues can be, and we will cover, among others:

• Risk analysis related to the threat of electric shock and arc flash hazards in Europe.
• Selection and proper use of personal protective equipment (PPE) for arc flash protection.
• Review of technical solutions improving electrical safety in Europe.
• Modernizations and optimizations of electrical installations in terms of safety.
• Experiences from the European market in various areas.
• Modern technologies for mitigating the effects of arc flash.
• Case studies – best practices and common mistakes.
• Legislative updates – European standards for electrical safety.
• Electrical Safety Plan for workplaces – first steps, how to begin.

Example of a practical situation – what can go wrong? 

Imagine that one of the main low-voltage switchboards, 415 V, has an arc flash energy level exceeding 40 cal/cm², which in practice means extremely high consequences of severe burns or even fatal accidents. From the outside, the switchboard looks fine – the problem can only be detected during a detailed assessment and analysis. What will happen if a failure occurs under such conditions? What will be the consequences for your company and your people? And what if we don’t even know that the potential hazard is over 40 cal/cm²? 

At the conference, we will show practical solutions – you will learn how to detect such threats early, apply modern arc flash protection solutions, and reduce risks effectively.

How will ESCEU help participants? 

Participation in the conference will bring you concrete benefits: 

• Gain practical knowledge from top European experts.
• Learn best practices for workplace electrical safety and arc flash protection.
• Network with solution providers and industry leaders.
• Improve your company’s compliance with electrical safety standards EU.

Join ESC EU 2025 – put electrical safety first 

The Electrical Safety Conference Europe 2025 will take place on October 23–24, 2025, in Kraków. Don’t miss this opportunity to stay ahead – book your place at esceu.eu today! 

Remember, electrical safety is an investment that always pays off.

Why it is important for us to do review? 

Recommendations as per IEEE 1584.1 should be included in Arc Flash Risk Assessment. It requires evaluating project, implement recommendations, re-do calculation. Physically, it should be a separate part or chapter in our report, so end customer can see influence or our proposed improvements. Sometimes our improvements in one area may affect negatively other parts of the electrical network. This often happens when an electrical system has a lot of non-selective protection devices. 

Step #9 is not a real step. Results review is constant activity during project. It is needed to : 

• Review any data quality issues and abnormal results or errors
• Identify high incident energy locations
• Identify equipment short circuit withstand rating failed equipment (panels, breakers, etc.)
• Identify protective devices non-selective operation (very important) 
• Identify worst case scenarios or combination of it

What’s next?

Once we have it done, we need to review arc flash results and protective device coordination and assess possibilities for improvements. This is where things are starting to get more complicated. There are multiple ways to do it and it partly depends on: 

• What we would like to achieve (zero risk, reasonable approach, or budget approach) 
• What was scope of work (contract details) 
• How far we can go with recommendations (budget, technical possibilities, equipment in use)

This is a good time to have a technical meeting with customer to discuss initial findings and identify technical possibilities if it was not done earlier during scope of work discussion. To improve the situation, we can use different mitigation and elimination arc flash techniques. It usually depends on initial incident energy results and combination of solutions mentioned below. All of this should be closely discussed with customer. 

What possible solutions do we have? 

Most common solutions to reduce or eliminate arc flash incident energy are: 

• Improving protective device settings – this is usually a big step as it is compromise with selectivity study, so two (usually opposite)  requirements at the same time. 
• Exchange protective device to new type e.g. retrofit old LV breaker with new type with digital trip unit, change fuse size/type, exchange MV protection relay with digital type.
• Exchange/ retrofit LV switchgears with new type –  it may be higher separation form, arc resistant, and it will allow for further modifications.  
• Install Fibre Optic Arc Detection system – add-on to switchgear, requires some re-wiring, but most of the time is possible even for old equipment (depends on system).
• Install Arc Quenching device –  add-on to switchgear (extra panel) or comes with new switchgears if system is replaced. 
• Use ZSI (Zone Selective Interlock)  in LV breakers – requires communication wires between breakers and requires new trip unit  (sometimes trip unite change is enough in LV breaker, depends on type).
• Use ARMS (Arc Flash Maintenance Switch) function – extra functionality of some LV breaker trip units, simple solution with right trip unit. 
• CLR (Current Limiting Reactors) – specific topics, as it can make it better and worse when reducing short circuit current.  
• Programmable Maintenance Switch for MV relays –  MV version of ARMS programmed into relay with some minor wiring needed for activation by SCADA, LOTO switch etc. 

How long it takes and how to handle it on site? 

Preparing recommendations takes time, but it is well spent time. As IEEE 1584.1 recommends, it should be part of every arc flash study. 
Once we have report with information what to do, we need to implement it on the site. Improvement process can take weeks, months, or even more than a year as it depends on the size of facility.  Since this process can take a while, it is good to already use our ”existing” results and install labels and match PPE based on it.  
Upgrades or protective device settings changes should be done exactly as proposed in report. Otherwise, we can end up having different calculated results than in real situation.  Every change should be noted and evaluated as part of “as built” documentation and any changes should be implemented in the model and results updated. 

What means existing situation? 

This step ends first part of arc flash analysis. It is called existing or as built situation as it provides information’s about incident energies and arc flash boundaries of current situation without any improvements. It is important to identify existing situation because: 

• it allows installation owner to act fast and provide temporary solutions to prevent staff from arc flash if necessary 
• implementing recommendations can take some time even counted in years, depending on size of facility, so existing results will serve as a base 
• it is a reference point for comparison of results and providing recommendations  

What standards to follow? 

We prepared base model, and now it is necessary to add arc flash related data and parameters. It is worth to mention that we are focusing on incident energy calculation and not table method. (see NFPA70E for details). Possible calculation standards and reference papers are: 

• IEEE 1584 – 2018 IEEE Guide for Performing Arc-Flash Hazard Calculations (worldwide) 
• DGUV Information 203-077 (Germany) 

Since I am focusing on European customers or locations it is also recommended to follow EN/IEC/CENELEC/VDE/BS specific standards to align our results more with IEC: 

• IEC 60909 – Short-circuit currents in three-phase a.c. systems – Part 0: Calculation of currents 
• IEC 61660 – Short-circuit currents in d.c. auxiliary installations in power plants and substations – Part 1: Calculation of short-circuit currents 
• IEC 60076 – Power transformers – Part 1: General 
• IEC 61439 – Low-voltage switchgear and controlgear assemblies – Part 1: General rules 
• IEC 62271 – High voltage switchgears 
• Local references for protection (if any) 
• IEC 60364 – selected parts  
• BS 7671 – 18th Edition The IET Wiring Regulations 
• NEN 3140/3840 
• VDE 0100 series 
• Etc. 

What Arc Flash is about? 

Our goal is to identify incident energy for modelled installation. I am writing modelled as it depends on scope of work, and sometimes it will be only part of the whole system. The most dangerous effect of an arc flash incident is tremendous temperature up to 19000 °C. This what arc flash calculation is all about. To identify how much energy can possibly be released and allows us to think in advance how to protect our life and do it the right way. 

Few words about calculation 

In most cases it will be done acc. IEEE 1584-2018 but depends on voltage level, AC or DC there are some very useful papers recommended in NFAP70E, IEEE 1584 or by equations by EPRI, ArcPro and tables by OSHA. Into this we will dive in next articles. 

How to present results? 

We have now arc flash results of our facility model for existing situation. How to present it? What to comment? To keep quality of our work it is recommended to give even brief explanation of results. Technically it is a bridge between existing situation and our future recommendations.  Depending on software or data processing tools we can present results in many forms. My recommended combinations to keep it simple and easy to read are:

• Single Line Diagram(s) – overview with Arc Flash results, e.g. Incident energy cal/cm2, AF boundary and/or AF label number (in PDF, dwg) 
• Arc Flash table – summary with all results worst scenario and/or per scenario if required 
• Colour coding – advised to use it SLD’s and tables as it is easy to find locations with higher energies (depends on how we set up colours but recommended is to follow NFPA70E) 

Some examples: 

Or by table:

What is Equipment Evaluation? 

Equipment evaluation, equipment sizing or device withstand rating verification is based on short circuit results. It verifies if short circuit rating of electrical equipment is high enough comparing to calculated short circuit current. Such calculations should be normally included in design phase however for existing installation it is recommended to verify it, especially when there is no previous design report available. 

Why is it important?

Proper sizing of equipment is crucial for safe operation under normal and faulty conditions. Cables, switchgears, breakers, transformers are design to withstand specific short circuit current in time. For proper operation of the breaker, it is critical that the breaker can withstand specific currents. If it is undersized, it can lead be damaged and pose threat to people and rest of electrical installation. 

How this relates to Arc Flash? 

It is included as a recommended step in IEEE 1584. Besides this, it is important to know that our equipment withstand rating is related with performance under fault conditions and normal operation. Constant overload or dynamic stress can cause damage to it and affect proper operation. This can lead to nuisance tripping, no tripping, thermal damage or fire etc. We can select worst case scenario out of multiple scenarios, however for experienced engineers it is easy to identify it. 

Example: 
We have low voltage switchgear rated 2000A 50kA/1s 105kA peak. If we do not know peak value, it is good to check in IEC 61439 table 7 for details.

We calculated two values in two scenarios: 

1. Ik” ≈Ith=46,45kA and Ip=100,5kA it is at the end of rating but can be accepted. In practice, it is good to keep 5-10% safety margin. 

2. Ik” ≈Ith=53,38kA and Ip=119,44kA – this switchgear rating is too low, and we need to look for higher short circuit rating or verify short circuit study input data first.  

When comparing short circuit results with different equipment, IEC 60909 comes with help and indicate which values to compare: 

Summary of equipment evaluation using SKM Power Tools

Below is an example of summary of equipment evaluation for switchgears and panel boards made with use of SKM Power Tools in this case. It can look different for other software’s like ETAP, CYME, EasyPower, DigSilent however core values should be similar. Such verification gives a very useful overview and directly indicates possible rating issues.  

In specific cases it is necessary to verify X/R or R/X of network and network time constant if not known as it affects results. Especially when local generation exists on site, This is very visible in marine and offshore installations. We need to keep in mind also renewable sources, battery storage systems, (DR) UPS-es with bypass in our calculations.

What Is Selectivity Analysis in Arc Flash Studies? 

It can be also called Protective Device Coordination (PDC), Selectivity Study, Discrimination Study. It is usually mandatory analysis for new electrical installations but also applies for upgrades, retrofits, or major electrical installation modernizations. Protective Device Coordination is a proper selection and settings of protective devices in order to isolate only faulted branch or place. If made properly, it will limit damage to installation itself and connected devices. A very important part of Selectivity Analysis is to eliminate fault as close as possible to the source of fault without affecting operation of the system. 

Why Is Selectivity Analysis Important for Arc Flash?

Non-selective protection system can increase damage to the equipment, extend and expand downtime and costs related. In some cases it can lead to dangerous situation especially related with safety   like fire, shock hazard, automatic disconnection or arc flash etc. In some cases it may not react at all, and obviously we don’t want it. 

How Does Selectivity Analysis Affect Arc Flash Results? 

Arc Flash calculation requires us to determine protective device tripping time.  In previous steps, we already modelled all necessary protective devices like: 

• LV fuses 
• LV breakers (ACB, MCCB, MCB) 
• MV breakers with protection relays (electromechanical, digital) 
• MV fuses 
• and specific protection schemes like differential protection, fibre optic arc detection, arc quenching devices, arc flash reduction maintenance switches, etc.

Arc flash and selectivity requirements are usually contradictory, and it requires compromise in some situations. In order to lower arc flash incident energy, tripping time need to be as low as possible (faster tripping). On the other hand, standard selectivity requirements are pushing tripping time higher (slower tripping).  There are hardware solutions that can overcome this problem, but they are not always available or feasible (due to cost, retrofit possibility or technical issues).  

Selectivity and Arc Flash? 

Arc Flash analysis itself doesn’t require the system to be selective, however it is very useful to perform such analysis. This step is important as it allows us later to provide tailor made recommendations for improvements of selectivity and arc flash. Protective device coordination is a much bigger topic, and it is very often omitted in arc flash analysis leading to identification of only existing situation while good practice is to focus on possible improvements. In order to do it right, we need to identify system issues like: 

• wrong settings of protective devices  
• non-selective areas 
• under protected equipment like cables, transformers, switchgears, and motors 

 The best way is to split analysis in two parts: 

• first step is providing information for “as build” or “existing” situation 
• second step is providing recommendations for selectivity and arc flash improvements 

Below sample of two TCC’s for existing and recommended selectivity for transformer branch. 

Selectivity Analysis Findings and Observations 

Left TCC shows a partially selective system, and it can be seen that MV relays are set with definite time settings, which is very common practice. There are few areas which can be discussed here: 

• Overlapping overload LV and MV settings may lead to MV side nuisance tripping, which we don’t want as it will de-energize the complete system and access to MV substation may be restricted or not possible. 
• MV and LV side transformer cables are not protected properly against short circuit currents 
• Transformer short circuit protection can be improved for primary and secondary faults 
• Overall arc flash results for 11kV and 415V switchgears can be improved  

Arc Flash Results Comparison – Existing vs Recommended 

Component	Existing IE cal/cm2	Recommended IE cal/cm2
BUS-11kV	18.2	6.18
BUS-LV 415V	11.1	2.4

 
It needs to be noted that in some situations it is a compromise. This means that in order to improve arc flash results, we will sacrifice selectivity and vice versa. This doesn’t happen very often and nowadays, we can use communication based protection solutions, interlocking schemes, arc flash maintenance switches to name a few.   

Practical System Modelling

Once our model is ready, we can create short circuit scenarios. This depends on system, but most often in Europe we will use IEC 60909 or local harmonised versions.  Since we know that our focus is on arc flash analysis, equipment evaluation and protective device coordination, we need more than one scenario.  

For a simple industrial system, this will require creating at least two scenarios: 

• Minimum short circuit current  (Utility min short circuit power, no motors etc.) 
• Maximum short circuit current (motors contribution, C=max, etc.) 

For complex systems, multiple scenarios are needed due to possible system configuration. This involves:

• Parallel source operations (PV, Generator, Utility) 
• Parallel transformers (closed or open tiebreaker) 
• MV ring operation (open or closed) 
• Motor contribution (big motors separately modelled, VFD with bypass etc) 
• Generator mode (emergency operation, normal operation) 
• UPS mode (bypass or normal) 
• System specific configurations (Open, closed breakers, test lab modes etc) 

Short circuit results depends on all of those factors. Additionally, it makes difference if we calculate fault close or far from generator which is affected by AC decaying component.  IEC 60909 representation gives clear overview of this behaviour. 

Short circuit analysis will be used to identify worst cases. This means minimum and maximum short circuit currents.  Results of this study will be used for further calculations, so it is important to validate it. 

How results can look like? 

It can be summarized in table which helps to find right data. Additionally, it is nice to show partial results on a single line diagram (keep it readable). Some examples below:  

As mentioned earlier, it could be that scope of work contains part of the network and the rest is not included. While this is fully understood from cost point of view, it may have big influence on end results. Since we are looking for short circuit current which will lead to (usually) the longest tripping times and highest incident energy, it is important to be not too conservative. Narrowing analysis to part of installation can end up with not realistic results and over/under sizing PPE, leading to wrong conclusions and costly recommendations. This is something we would like to avoid.  

How we use short circuit results? 

• Equipment evaluation will use maximum short circuit results to compare withstand rating of equipment like cables, switchgears, breakers, transformers etc 
• Protective device coordination (selectivity analysis) require both maximum and minimum, sometimes scenario specific results for protection settings calculations 
• Arc flash analysis requires worst case combination (min, max, etc)  in relation to protection scheme  

Coming back to partial short circuit calculation, It is site specific and requires recommendation from a power system engineer for each project to make it right (see scope of work kick-off discussion).  

Common issues related to short circuit data  

Typical situations: 

• we have previous short circuit study, but it lacks min max values and was too general missing short circuit sources especially generators and motors 
• we don’t have study, but our scope of work is limited, so a big part of the system won’t be included in short circuit study  
• no main transformer data or hard to get (the same for utility data)  
• ring topology with multiple short circuit paths (for large sites) 
• parallel operations for utility and other sources (situation for part of system modelling).

How System Modelling Fits into Arc Flash Analysis

This step is beginning of engineering part. Nowadays, it is common and reasonable to use power system software to perform analysis.  Most common in use are SKM, ETAP, Easypower, DigSilent, CYME and others. It still can be done by hand or with use of Excel, however complexity of electrical systems will make it not efficient and costly. CAE software is a great and helpful tool, but it is only as good as the person that is using it. We need to remember that what comes IN goes OUT. Proper modelling is a must. 

System modelling requires us to establish few areas: 

• System topology and operations modes 
• System prospective short circuit current  
• Equipment data 
• Electrodes configurations (new from 2018) 
• Required scenarios   
• Assumptions  

System topology and scope of work 

Once we collected all the data or enough data, modelling can be started.  It can vary from one software to another, but a common part is to create a digital model as base for further modifications and adjustments. In Step 1 we focused on scope of work and here is why. We can evaluate: 

• complete system (in electrical terms) 
• part of the system  

Complete system study allows to determine multiple scenarios and finding min and max short circuit current. If we evaluate part of the electrical system, we need precise data about short circuit current in the evaluated part. It is very common for short circuit studies to focus only on max values for equipment sizing. The first tricky thing behind arc flash is that max current doesn’t always lead to the highest incident energy. 

Operation modes 

When system model is ready, attention is needed for scenarios, proper standards for calculations and adjusting analysis options. While software generally helps, it is only tool that can be used good or bad.  We are following mostly IEEE 1584 method for calculating arc flash in AC systems. This for European market requires some adjustments: 

• short circuit analysis method acc. IEC 60909 
• busbar gaps to follow IEC 61439 and IEC 62271-1 (recommended) 
• working distance is another topic, however IEEE 1584 standard options are reasonable  

Scenarios

Our base model is ready, so it is time to create scenarios.

We need to keep in mind that our arc flash analysis focus is to identify and provide recommendations for improvements. This means that scenarios need to take into account :

• Short circuit study results 
• Protective device coordination (selectivity) 
• Arc flash analysis results 
• *Load flow study (if included) 

Optionally, depending on our system we can consider: 

• BESS system connected 
• PV/WIND, etc. system connected 
• UPS, RUPS, DRUPS systems  
• CLR (Current Limiting Reactor) in operation 
• Specific switching arrangements (parallel transformers, multiple generators, etc.) 
• Protection specific functions modes (ARMS, arc fibre optic detection, arc quenching devices, differential protection, etc.) 

Equipment and configuration 

Data retrieved from site visit, documentation and provided sources need to be carefully implemented into digital model. Sometimes it requires verification of database and validation of available models for errors. Those issues have different weight, and it is related with installation size.  Most recommended is to use data verified by site visit, especially for settings of protective devices. Electrode configurations are a new topic from latest 2018 release of IEEE 1584, and it will be discusses separately in next chapter. 

Assumptions 

From my experience so far, assumptions are almost impossible to avoid but need to be minimised. This happens because often it takes too much time to retrieve data from: 

• utility operator  
• locations that can’t be de-energised due to ongoing process (sometimes it can take months to get the data) 
• restricted access to locations (eg. transformer rooms or utility switch rooms) 
• old equipment (missing data sheets, etc.) 

Usually some reasonable assumptions can be made based on experience. It is always project specific, but some general assumption list can be made, like: 

• transformer short circuit voltage/impedance rating 
• fuse types and tripping curves  
• low voltage breakers types and settings (similar model based) 
• system short circuit power  (depends on configuration, sometimes it has little effect for end results) 
• induction motors data 
• switchgears and panels ratings 
• cable lengths and type (this is tricky and requires results review).

Arc Flash Analysis Step by Step #3: Site Data Collection

Every arc flash analysis requires accurate input data — and site data collection is one of the most critical steps in the entire process. Unlike other power system studies where conservative assumptions are acceptable, arc flash analysis demands reasonably precise data. Why? Because the highest short circuit current doesn’t always lead to the highest incident energies. This is especially important for Low Voltage installations, which are often underestimated compared to High Voltage systems — when in reality, LV hazard levels are frequently higher. 

Why Accurate Data Collection Matters in Arc Flash Analysis

It is important to be accurate when collecting data, and data needs to be based on up to date documentation to reflect existing installation. Very often there is big discrepancy between what is on the drawings and what is in reality. While some facilities maintain documentation very well, others not always. It is very good practice to verify documentation vs as-build reality. This means site visit for data verification and data collection.  Key reason for such decision are: 

• Lack of expertise on site 
• Lack or limited documentation and related difficulties (system mapping) 
• No available staff for arc flash data collection support 
• Independent engineer opinion vs employee  

What Affects Arc Flash Analysis Data Collection?

Every installation is different and data collection also. It depends on: 

• type of business sector e.g. chemical, oil & gas, industrial, automotive, BESS, PV & WIND, marine 
• system size and voltage range (AC, DC, LV, HV, big or small system)  
• available documentation and drawings 
• local support (skilled electrician, engineers, etc.) 

Who Can Perform Arc Flash Analysis Data Collection? 

Since we are talking about low and medium voltage systems, it is required for such person to be certified or authorised electrician or engineer. Data collection can be an elevated risk process since it requires access to electrical switchgears, cabinets and machines. Very often, some covers need to be removed in order to retrieve the right data. It is good to arrange: 

• introduction meeting with technical team 
• provide general plan and if needed to arrange work permits 
• follow site specific safety rules  

What Data Is Required for Arc Flash Analysis?

It depends on specific facility profile and amount of documentation, however some general list can be made. If documentation is good enough, It is good practice to prepare a list of all (known) necessary information’s needed. What we can expect to identify and collect: 

• System operation modes  (normal mode, generator mode, emergency, etc.) 
• Utility fault data, three-phase and single line-to-ground short circuit power, X/R ratios at the power delivery point 
• Utility feeder(s) protection settings, relay type, CT ratio 
• All available documentation for old equipment (generators, relays, breakers) 
• Single line diagrams copy (if on paper only), even old are useful 
• Switchgear, switchboards data (short circuit withstand rating, nominal current, busbar gap, dimensions) 
• Cable data, type, length, conductor material, amount per phase 
• Generator data current decrement curves as per manufacturer tests, nameplate data  
• Transformer data, transformer type, winding connection, voltage ratio, rated power, short-circuit impedance (nameplate data) 
• Motors data  >37kW nameplate and control system type (VFD, DOL, SS, etc.) 
• Medium voltage protective relays type, manufacturer, settings, and CT ratios. 
• Low voltage circuit breakers data and trip unit type and settings 
• LV and MV fuses size and type 

Specific data for AC and DC system analysis

• type of system grounding (for protection and short circuit study) 
• BESS:  battery energy storage system type, designed power, batteries configuration, physical gaps between “+ and –” electrodes, DC protection type and settings 
• PV: inverter type, short circuit specification, configuration of modules connected, topology, DC protection type and settings 
• WIND: generator data sheet and type, converter data and protection type, system topology and min max wind generators connected 
• DC systems – verify electrode gap (min max), short circuit protective device, system voltage  (model range check), DC source type for short circuit study 
• UPS: configuration and working modes (external by-pass, electronic by-pass), power or battery package, UPS short circuit behaviour (current and voltage)  

Example of data collection summary

Site visit and data collection activities need to be performed according to site safety rules. It also requires a site authorised person to accompany the engineer during data collection and allow access to all necessary equipment, switchgears, and switch rooms. Data should be collected and documented as it serves later as a reference point for any assumptions and comments. Good practice is to transfer all the information’s later back to the customer for further use and upgrades. It can look like this example below.

Defining the Scope of Work

In the initial phase before arc flash analysis, it is important to identify scope of work.
Below, I highlighted the few most common things that will have the biggest impact: 

• Customer specific targets (system retrofit, specific safety issues, modernization, etc.).
• Which part of installation? (Complete system or part only.) 
• System voltage LV, MV, or HV.
• AC only or AC & DC.
• Type of facility (test lab, marine, data centre, industrial, etc.).
• Type of DC installation (BESS, UPS, UPSaaR, DRUPS, DC motors, DC generators, etc.).  
• Operation scenarios, possible system configurations.
• Related customers procedures (EHS, arc flash corporate rules).
• Any other relevant information.

Where to Find the Input Data? 

Our next step is to have a kick-off discussion between a Power System Engineer and a customer. This is so far the easiest way to explain important details and identify scope of work for arc flash analysis. To assess scope of work, we need information which can be found in: 

• Documentation (previous studies, load schedules, instructions).
• Single Line Diagrams with MV and LV network data.
• Any excel load lists, motors lists.
• EHS instructions or procedures.
• Site specific requirements and documents.

What are limitations for arc flash analysis? IEEE 1584, EPRI and OSHA 1910.269 models.

It is very good if installation falls into IEEE 1584 model range, which is:

• 208 V to 600 V: 500 A to 106 000 A (AC)
• 601 V to 15 000 V: 200 A to 65 000 A (AC)

Above 15kV we will follow EPRI or ArcPro (OSHA 1910.269) based guidance up to 800kV system range, however supply voltage above 15kV for industrial application happens only in specific situations. Practical rules for arc flash evaluation limits looking from protective device perspective is to start from (or stop at):

• LV circuit breaker  ≥63A 3P (MCB, MCCB)
• LV fuse ≥ 100A 
• LV Motors  ≥  50HP (37kW) 
• MV system up to 15kV (*>15kV EPRI / ArcPro OSHA 1910.269) 
• DC systems up to 1000VDC

What If Electrical System Documentation Is Missing?

We have two options: 

1. Wait for documentation update (longest).
2.  Arrange site visit for system estimation (fastest).

System estimation visit goal is to do a fast review of installation and collect information’s about:

• size of the electrical system
• condition of the installation
• type of the equipment
• amount of the equipment

Lack of documentation is an obstacle, but for experienced engineer after such visit it should be possible to provide reasonable estimation on cost and general follow-up plan. Missing documentation is less comfortable situation for installation owner, thus it is good to have flexible approach and provide support.

Single line diagrams mapping – A Smart Alternative

If no or little documentation exists, it is necessary to made it. Since arc flash analysis requires some specific data to be collected, it is a good idea to arrange data collection with system mapping. What is system mapping? It is simply creating single line diagram of the system (MV to LV feeders). This process and can take days or weeks depending on system size. It has an important additional value as it can be combined with data collection for arc flash analysis. Thus, it will save time and money providing valuable system overview and all details necessary for further analysis. 

Why Arc Flash Myths Are Dangerous

When I started with arc flash, it took some time even for an electrical engineer to sort out what is important when it comes to an arc flash analysis.  It was harder since you can find quite some arc flash myths going around, which are not helpful. In the worst case, it can cause someone death or severe health issues. To give you perspective, it can be like driving a car with seat belts made of paper without knowing it. Misconceptions created around electrical safety makes it harder to transfer knowledge as people believe it is not needed. Living in safety bubble is comfortable as you do not need to do nothing extra, any safety plans, any risk assessments just find proper excuse or justification to existing situation. This unfortunately is a debt you take on someone else personal safety.   

Are You Living in a Safety Bubble? 

If you find below myths suitable or true, do me a favour and make step outside of it and check it again. My colleagues from US taught me a very useful lesson: If you do not know if the decision is good or bad, imagine yourself explaining your decision in court after accident. 

Common Arc Flash Myths Explained 

Let s start with the most common spells I hear people saying. Below what I found till now and a bit more:

1. Arc Flash Risk Assessment is not needed – NOT TRUE
   It is hard to call it obligatory in all EU countries, but it is necessary. In EU, we have EN 50110 (harmonised in each country under local norms)  which identify arc flash as a hazard and requires risk measure. If personal safety is not enough for someone, keep in mind that like in UK there are huge fines and prison sentence already happening.  
2. We got PPE APC1 and APC2 we are covered – NOT TRUE
   Very common in Europe but If PPE selection was done just out of blue it is not safe as it should be. Usually, it looks like this PPE Class 1 for LV installation and PPE Class 2 for MV and everything we’re afraid of. Does not matter what you use if it is not based on proper numbers it just creates a safety bubble, and it will be too late when flash accident will verify it. 
3. Arc Flash is only for big switchgears – NOT TRUE
   IEEE 1584 indicates that we can expect sustainable AC arc flash down to 240V AC with 2000A available short circuit current. Quite low and in practice it usually means that analysis is going down to 230V 63A MCB (Miniature Circuit Breaker) or 100A fuse.  
4. We don’t work live; we don’t need arc rated PPE – HALF TRUE
   It is great if company can completely reduce live working to zero.  What about measurements, live maintenance, proving dead checks? After we de-energize the system, we need to prove no voltage. This point requires PPE and if you think different check THE MARK STANDIFER STORY (it is on YouTube). Till now, all companies I saw do some tasks on live equipment. 
5. Arc Blast is deadly –  HALF TRUE
   There was misconception in the past that above 40 cal/cm² arc related pressure blast is so big it can kill people. It was related with fact that previously every location above 40 cal/cm² was called dangerous and no live work was allowed due to lack of PPE rating. Till now there is no fatal accident recorded due to arc blast. Arc blast exists but with proper PPE it can be handled if needed (yes you can estimate it if needed). Also, for Power System Engineer, it should be possible to lower energy below 40 cal/cm² in most projects. 
6. Low cal/cm² can be ignored – NOT TRUE
   It cannot be ignored and should be addressed properly. Sometimes people tend to ignore low level arc flash locations with below 4 cal/cm² assuming it is not that bad as 40 cal/cm². Energy of 4 cal/cm² may sound small, but it will cause 3^rd degree burns the same way as 40 cal/cm². Difference can be surface of burns or your chance to survive it.  
7. 400V AC is safer than 11kV – USUALLY NOT TRUE
   I believe this comes from electrocution point of view. Medium voltage sounds more dangerous than low voltage, but when it comes to arc flash, it is counterintuitive. It all depends on electrical system design, protection setting and few more things.  Most of the time, low voltage switchgears are identified with much higher arc flash incident energy than medium voltage switchgear supplying it. This is an effect of much higher short circuit currents at LV level in general, arcing current/bolted current ratio that can reach even 38% of bolted fault short circuit current and extended tripping times which are caused by it. 
8. New switchgear is safe – SHOULD BE TRUE
   It all depends on what you buy. Assuming your switchgear is not arc resistant or IAC, technically there is no big difference from arc flash point of view. Imagine that you had old panel identified with 35 cal/cm2. Now it was 1:1 replaced, and protective settings were replicated (very common). What is the difference now? It is still 35 cal/cm2. What can or should change are better covers to lower risk of initiating arc flash or electrocution, motor operated breakers, better form of separation and improved protection units. Such solutions are usually driven by arc flash risk assessment combined with selectivity, short circuit, and equipment analysis, otherwise it is hard to see direct improvement.  Just having new switchgear is not enough to say it is safe, and we do not worry about arc flash any more. Keep in mind that live maintenance, measurements, or voltage check is done with doors/ covers open.  

What Is an Arc Flash Risk Assessment?

Arc flash risk assessment is the foundation of improving electrical safety in industrial and commercial installations. Arc flash incidents are among the most severe hazards in electrical installations, with potentially catastrophic consequences for people, equipment, and infrastructure. This series aims to deepen your understanding of arc flash phenomena, provide a systematic knowledge framework, and guide you through the essentials of a thorough risk assessment in this domain. Let’s begin!

The Essentials of Arc Flash Risk Assessmen

Performing a proper Arc Flash Risk Assessment requires precise calculations and adherence to established guidelines. Depending on the region, these include:

• IEEE 1584 – Guide for Performing Arc-Flash Hazard Calculations (global),
• NFPA 70E – Handbook for Electrical Safety in the Workplace,
• DGUV 203-077 – (Germany),
• Experimental methods and engineering best practices.

This article outlines a comprehensive process to help you understand what goes into a detailed and professional assessment.

How Does an Arc Flash Risk Assessment Project Work?

The following steps for a typical project give us an idea of what we should expect. Of course, the requirements can be expanded depending on the particular installation or specific customer requirements.

The standard IEEE 1584.1 outlines the necessary components of an arc flash risk assessment report and specifies mandatory documentation. A superficial analysis that merely provides a table of results, without actionable insights, is of little value. Below is a structured, 16-step process to ensure a reliable and actionable outcome.

The 16-Step Arc Flash Risk Assessment Process

1. Define the Scope of Work – Collaborate with the client to establish the scope, typically covering everything from the connection point to overcurrent protection rated at 63A in a 400V network.
2. Data Collection – Conduct on-site inspections and review electrical documentation, network schematics, and operating descriptions.
3. Model Creation – Develop a model of the electrical installation using advanced software (e.g., SKM, ETAP, CYME, Easypower).
4. Short-Circuit Current Analysis – Perform calculations based on standards (IEC 60909, ANSI, IEC 61660, etc.) for various operational scenarios.
5. Selectivity Analysis (Current State) – Prepare protection device characteristics and documentation.
6. Equipment Short-Circuit Rating Assessment – Verify the durability of switchgear and breakers against calculated short-circuit currents.
7. Arc Flash Analysis (Current State) – Calculate arc flash incident energy and determine PPE requirements for all switchgear under the current setup.
8. Results Review – Identify recommendations to improve selectivity, reduce arc flash energy, or highlight equipment that exceeds its short-circuit capacity.
9. Selectivity Analysis (Recommendations) – Propose adjustments to protection device settings and medium-voltage (MV) protections to enhance selectivity.
10. Arc Flash Analysis (Recommendations) – Recalculate based on proposed settings or technical solutions.
11. Reporting – Compile all results, recommendations, modeling data, single-line diagrams, and informational labels in formats like PDF or Excel.
12. Training – Provide introductory training on arc flash risks, either on-site or via teleconference.
13. System Labeling – Supply and install informational labels on analyzed switchgear.
14. PPE Selection – Assist in selecting appropriate Personal Protective Equipment (PPE).
15. Report Presentation – Discuss the report findings and technical solutions with the client.
16. Updates – Regularly update results every five years or after significant system upgrades.

Why a Thorough Arc Flash Analysis Matters

Superficial assessments may offer quick results, but often leave clients with insufficient insights and unresolved risks. A comprehensive analysis, supported by actionable recommendations and system improvements, ensures both safety and efficiency.

In the following articles, we’ll dive deeper into each phase of the process, offering practical solutions to enhance electrical safety and mitigate arc flash risks.

What is Arc Flash?  

Arc Flash also known as flashover, electric arc, arcing fault, etc. An electrical arc is a form of electrical discharge between two electrodes (anode and cathode). The name arc comes from the shape of discharge paths due to gas convective motion.  Due to gas ionization process it creates stable arc path which is heating up the gas and can reach up to 19000 °C. We are using this in controlled way in electrical welding machines or electric furnaces. Problems start when it happened unintentionally or by accident.

Why Does Arc Flash Analysis Matter?

Arc Flash as I wrote above can produce temperatures up to 19000 °C. When it happens in our electrical installation by accident, we need to be protected against it.  For example, to get 2^nd degree burn, we need 0,1s of 80 °C or 0,9s of 65 °C hot water. As you may see there is a huge gap, and you need to prepare for it in advance as It will be too late once it happens. I like the comparison to driving a car on the highway without seat belts or cleaning load gun in front of your face. 

What to Do Next: Starting Your Arc Flash Analysis

When it comes to arc flash there are multiple solutions, but before we jump into solving anything it is good to understand: 

• what we need to improve
• where improvement is needed
• why we need to do it

To do it in the right way, we need to identify possible arc flash incident energy levels in electrical installation. This is important as it allows us to: 

• identify incident energy for complete installation for proper overview
• identify locations on which we need to focus
• prioritize actions for improvements where it is needed at most
• create short term plans for fast solutions (e.g. fast PPE exchange)
• prepare planning and cost overview

At the end it will save us time and money as we can target precisely where to invest or improve safety.  Not to mention that as recent fines show (£600,000)  it is much, much, much, much    cheaper to be compliant than cost of possible accident and related fines in case of safety violations. 

Usually, for EU and worldwide customers, the best references are: 

• NFPA 70E table method
• NFPA 70E analysis method by IEEE 1584 (recommended)

See my next articles from Arc Flash Analysis Step by Step series.