Arc Flash Study Top 10 FAQs Part #3

How Does Everyone Else Do This? By Jim Phillips 3-Part Series ARC FLASH LABELS What do you list on an arc flash label when 
the prospective incident energy is greater […]

Arc Flash Study Top 10 FAQs Part #2

How Does Everyone Else Do This? By Jim Phillips 3-Part Series ELECTRICAL SAFETY PRACTICES Does your company or client permit energized work where the incident energy is greater than 40 […]

Arc Flash Study Top 10 FAQs Part #1

How Does Everyone Else Do This? By Jim Phillips 3-Part Series   There are many frequently asked questions about performing an arc flash study (risk assessment) and understanding electrical safety […]

Forensic Electrical Engineering Blog #3

Past – Present – Future 3-Blog Series By Jim Phillips, P.E. Blog #3: Evolution in Forensic Electrical Engineering There has been much advancement in the field of forensic electrical engineering […]

Forensic Electrical Engineering Blog #2

Forensic Electrical Engineering Past – Present – Future 3-Blog Series By Jim Phillips, P.E.   History of Forensic Electrical Engineering Some historical articles suggest the field of electrical investigations began […]

Forensic Electrical Engineering Blog #1

Past – Present – Future 3-Blog Series By Jim Phillips, P.E.   Blog #1: What is Forensic Electrical Engineering? Welcome to my 3-part blog series about the Past, Present and […]

Moisture Content in Electrical Cabinet

Question: Hello, At one facility I find that the condensation gathers on the inside surface of an enclosure, which can cause the rusting, short circuits, and breakdowns in electric and […]

IEEE 1584.1-2013

Question: Hello, good afternoon. Does the standard contain new information to consider for arc flash analysis? Thank you   Answer: No because we’re still on the 2002 edition. The new […]

Liability and Legal Action

It’s no secret that the United States is a very litigious country. Sometimes the more “interesting” interpretations that people use regarding codes, standards, design etc. tend to be more influenced […]

Include Date on Arc Flash Label?

According to the 2015 Edition of NFPA 70E 130.5(2), The arc flash risk assessment “…shall be reviewed periodically, at intervals not to exceed 5 years, to account for changes in […]

Adjusted Pickup Method – Shift Factor

I have been looking into the adjusted pickup method and associated shift factors used when multiple source bus configurations are being coordinated [ex. parallel generator systems two or more] and […]

Non-melting clothing

Our company in the past 2 years has implemented an electrical safety and control of hazardous energy program for employees world-wide. Our daily work-wear clothing minimum requirement is non-melting clothing, […]

Safe Return-to-Service Following a Maintenance Outage

Best Practices for a Safe Return-to-Service Following a Maintenance Outage Charles M. McClung, MarTek Limited Russell R. Safreed, PE, MarTek Limited Abstract Returning electrical equipment to service after a planned […]

2015 NFPA 70E Changes

The following is an article that I wrote a few years ago listing the major changes for the 2015 edition. It was originally published in the May 2014 issue of Electrical […]

How Many Arc Flash Labels on Equipment?

Question of the Week Some equipment may have multiple arc flash labels for a variety of reasons. Different operating configurations Equipment is long/large – including busway Equipment has different incident […]

Medium or high voltage training in U.S.

Recently a Fortune 500 company called asking if service technicians were “certified” to work on 4160 V equipment. This isn’t in the context of say the New Brunswick province where […]

ATS Protection and UL

In looking at the latest edition [7th] of UL 1008 for transfer switches I came across the following: “The circuit breaker must include an instantaneous trip response and shall not […]

Hot Stick Testing

Question: Everyone, I got this question from a client. He asked if it’s necessary to have their hot sticks tested? Understand this company has nothing higher than 480 volts on […]

Arc Flash Labels-PPE Category

In the NFPA 70E-2015 Handbook, page 122, 130.5(D) states incident energy or PPE category shall be on the equipment arc flash label, but not both. Yet when reviewing Annex H […]

Reducing Arc Flash I/E At Fire Pump Controllers

Question: What are you guys recommending to reduce incident energy levels on fire pump controllers fed directly from the secondary side of utility transformers? Answer: Can’t be done. This is a […]

Work on an energized disconnect

Recently, a client asked if there was something I could point to in the NFPA 70E Standard that specifically prevented a qualified electrician from working on a disconnect after it […]

120 Volt Arc Flash

I believe it to physically impossible to sustain an arc flash at 120 V but can someone point me to the proof? Can someone indicate where a code specifically states […]

Arc Flash Label Updating – How Many Times?

NFPA 70E requires that an Arc Flash Risk Assessment be updated when a major modification or renovation takes place. It shall be reviewed periodically, at intervals not to exceed 5 […]

Picture of the Week

    Hopefully you’ll never have to experience this on the job! Male chimpanzee Chacha screams after escaping from nearby Yagiyama Zoological Park as a man tries to capture him […]

Using gloves with a stick

1910.269 requires arc flash protection for hands with exceptions when wearing leather protectors over rubber gloves, and when wearing heavy duty work gloves. The workers state that sticks should be […]

DC Arc Flash Boundary

Could i use the (DB) empirically derived model equation of IEEE Std 1584-2002 to calculate the Flash-protection boundary (for box configurations) and the Lee (DB) equation (for open air configurations)? […]

Maintenance of LV components inside HV cabinet

Good Morning All, I am from the Safety Office and our organization prohibits working on electrical components/systems above 600V. I have a situation that I need advice on. Here is […]

RELT or ARM Arc Flash Labels

It always seems as if we are kicking the dead horse on arc flash labels but I was just interested in your opinion of how to label a piece of […]

2017 NEC 240.87 Instantaneous Trip

The NEC requires that where a circuit breaker’s highest continuous current trip setting is rated or can be adjusted to 1200 Amps or higher, a method for reducing the arc […]

Low Fault Current on Utility System

Here is the situation: It is a municipal system, very rural, and has long single phase runs with low fault current. For example: 2400 delta single phase lateral ends up […]

Do you use equipment/methods based on IEC Standards?

This week’s “Question of the week” is coming from Frankfurt, Germany. This week I have the privilege of attending the International Electrotechincal Commission’s 80th General Meeting as the International Chairman […]

Arc Rated Clothing Causing Health Effects

We have gone to wearing cotton HRC2 (8.6 cal/cm2) uniforms and about 10% of the employees have found the clothing to cause burning and itching with at least one case […]

Air Conditioner Motor Contribution

I’d like to hear how some of you are handling Air Conditioner motor contributions in your models. I’m working off a one-line to build the model (while the site is […]

Lock Out / Tag Out Simple vs. Complex

OSHA and NFPA 70E refer to a Simple LOTO as involving only one person/conductors/circuit part(s). A Complex LOTO is when there are conditions such as more than one person/circuit/shift/source involved […]

IEEE 1584 and Overdutied Breakers

I guess this directed at IEEE 1584 Committee members (Jim) and I know you can’t say too much but is overdutied breakers/equipment going to addressed in the new IEEE 1584? […]

Replacing AF Labels

I will be updating arc flash labels on numerous working locations which means the old label has to be removed and a new one applied. By design these labels are […]

Aluminum vs. Copper IE differences

I’m pushing through the brilliant book “Industrial Power System Grounding Design Handbook” by Dunki-Jacobs and Co. In it, the authors indicate that copper is endothermic (absorbs energy when converting from […]

How far would you go?

All – I found this installation the other day while in an area I am not officially in charge of. I called the person in charge and recommended he have […]

Falsified Arc Flash Study

As a electrical engineer who performs arc flash studies and investigates electrical accidents I have come across a company who is faking their arc flash studies. They go into companies […]

AF Boundary Marking

Hi, As per NFPA 70E, we have 3 boundaries to mark(AFB, limited and restricted). It is easy to mark and follow only one boundary which is greater than two. Sometimes […]

Short sleeves versus long sleeves

The industrial plant I work in has a policy that you must have long sleeves when inside an electrical room. Yesterday we had our annual “cold day”, where all turbine […]

Application range of methods in IEEE1584

Hello everyone, The application range for the empirical method is clearly defined : 208V to 15kV and a bolted fault current between 700A and 106kA. But for the theoretical method, […]

Arc flash detection relay

What is the practice for the use of arc detection relay trip time in the arc incident energy calculations? NFPA-70E recognized arc detection relay but kept under “Other Methods” as […]

Jim Phillips to Speak at 2016 IEEE/ESMO Conference

  LATEST NEWS September 12, 2016, Scottsdale, AZ: Jim Phillips, P.E., founder of and, will be a speaker at the 2016 IEEE/ESMO conference held in Columbus, OH on […]


AS I understand it in NFPA 70 E 130.7 table any Panel 240 volts and below require Category 1 PPE. Also NFPA says any voltage 120 volts Phase to Phase […]

Have you ever read IEEE 1584?

Just Curious – Have you ever read IEEE 1584 – IEEE Guide for Performing Arc Flash Hazard Calculations? -All of it -Some of it -No Click to ANSWER.

Bus Duct and Arc Flash Hazard?

I was asked to evaluate some “newer” bus duct technology that are finger safe, use a turn and lock connection or similar methods without turning off the power. It seems […]


Looking at the IE calculation there is a variable for grounding depending on what type system you have installed, and noticed that the grounding type can have a significant effect […]

Using Grounding Resistors

One of the forum member’s posts prompted this weeks question of the week. It is about grounding, more specifically – high and low resistance grounding. (some may use reactance grounding). […]

MCA – Minimum Circuit Amps?

How does one calculate the normal operating current of a load from the MCA rating, given that is all you have. Thanks. CLICK to Answer.

Preload indicating washers

Anyone ever heard of a preload indicating washer? Looks very simple. It’s a washer that crushes when the fastener reaches 80% of yield. According to Sandia Report SAND2008-0771 they are […]

NFPA 70E and Improved Electrical Maintenance

The duration of an arc flash can be greatly affected by the condition of electrical protective devices – i.e. circuit breakers, relays etc. NFPA 70E has been placing an increased […]

Tested vs. Engineered Series Ratings

One more question about series ratings. NEC 240.86 addresses series ratings “Selected Under Engineering Supervision in Existing Systems” and “Tested Combinations” Please refer to last week’s post and NEC 240.86 […]

Series Ratings NEC 240.86

The National Electrical Code article 240.86 addresses series ratings with the following: Where a circuit breaker is used on a circuit having an available fault current higher than the marked […]

ArcPro and Windows 10

Has anyone found a way to run ArcPro on Windows 10? I cannot even install it on Windows 10. Not sure about any 3rd party programs that could emulate a […]

X factor for Disconnect switches

Hello What is the optimal X factor for disconnect switches. I assumed it is 2 because that’s the default value that ETAP gives you. Am I correct for assuming this? […]

Arc Flash Shields in disconnect boxes

I repair UL listed appliances that are sometimes directly wired into a fused or unfused disconnect box if they exceed 50A. Sometimes I need to test the voltage on both […]

Existing Overdutied Equipment

This week’s question is a continuation of last week’s topic regarding overcurrent devices that do not have an adequate interrupting rating. When the calculated short circuit current is greater than […]

Fiber Optic Arc Flash Detection Modeling

I will start by stating that I am not 100% familiar with these types of systems [Fiber Optic Light Detecting]. In recent MV switchgear submittal the manufacturer [I assume at […]

Non Specific incident energy

I have started working at a manufacturing plant where the past practice is to put <1.2 cal on their arc flash labels. The thought being that any run less than […]

Short Circuit Calculations and Conduit Material

I recently came across a previous study that was completed for a facility that assumed a specific type of conduit [non-metallic/magnetic; PVC] vs what was actually installed [Rigid Meal Conduit], […]

Harmonic Correction Unit?

Harmonic Correction Unit? Would a Harmonic Correction Unit impact the incident energy during an arc flash in an MCC line-up? READ ANSWER

Normalized incident energy explained?

Can someone explain incident energy normalized, what is it and how it is obtained .Utilizing the Incident Energy at Working Distance -Empirically Derived Equation -NFPA 70E-D4.3, En = incident energy […]

Arc Flash Hazard Calculation Studies

Setting up the electrical enclosure

In the earlier years of NFPA 70E and the emergence of arc flash protection requirements, many people would use the NFPA 70E Hazard/Risk Tables to determine what arc rated PPE […]

Grounding Power Distribution Systems

The NEC contains specific articles that dictate when you shall ground, when you shall not ground, and when you are permitted – but not required – to ground. These code […]

OSHA, NEC, NFPA – Pieces of the Puzzle

The next time you are near the bulletin board at work, look for the poster that has the words “It’s the Law” and “OSHA” on it. It has probably been […]