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Arc Flash Forum Update

How Many Arc Flash Labels on Equipment?

December 7, 2016

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 energy for main/feeders such as some switchgear. There may be other reasons as well. This week’s question: What is the greatest number of arc flash labels you have seen/used on electrical equipment? 1 2 3 More than 3 (how many?) ANSWER

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Medium or high voltage training in U.S.

December 1, 2016

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 they actaully require such things at the unusual voltage of 750 V but rather this is in the U.S. in the Southeast. It smells like some training company is managing to hock something. Has anyone heard of this? Does it even make any sense? Granted there are 3 different major

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Face equipment or face away during switching?

November 30, 2016

Weekly Question: This week’s question was submitted from one of our forum members. I will post it here When locking out or resetting a tripped breaker on a CAT 4 system (actually extreme danger), I have one electrician that says he feels more comfortable facing the distribution than facing away. He argues that the shield will protect him better than the Balaclava. He also says that the force needed to reset a tripped (1200 Amp) breaker is easier when facing

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ATS Protection and UL

November 29, 2016

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 include a sort time trip response” as it relates to switches tested per 9.13.3.10 & 9.1.2.3. It seems different manufactures have different interpretations. So does this disqualify any breaker with an adjustable STPU / STD setting from protecting a 3-cycle [0.05sec] any breaker rated switch, even if the breaker has

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Hot Stick Testing

November 28, 2016

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 site and only uses these hot sticks to switch on and off 480 volt 30- to 200 amp bus duct fused disconnect switches. The bus in this factory is hanging well above the floor. If an employee needs to reach a bus plug, he uses a hot stick to access

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Regenerative Drive Contributions to Upstream Fault

November 25, 2016

Is there any information on what a regenerative drive will allow a motor to contribute to an upstream fault? I know ANSI has some standards for motor contributions based on <50HP or >50HP for across the line starters. We have some DC motors with regen drives connected to a 480VAC system and I want to model the contributions of the motors on the upstream switchgear. A few of these motors are 500HP or bigger. We used to use Easypower and

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Arc Flash Labels-PPE Category

November 22, 2016

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 in the NFPA 70E-2015 handbook, on page 279 it states “Arcflash PPE categories may be applicable when using incident energy method to perform an arc flash risk assessment. When performing an incident energy analysis, the arc flash labels created may include an arc flash category”. Am I missing something or

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Reducing Arc Flash I/E At Fire Pump Controllers

November 21, 2016

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 common practice but is very illegal in most cases. NEC is very specific in that overload protection (ie, overload relay) is eliminated and short circuit protection only remains. I have no idea why and I’ve had multiple fire marshals actually try to tell me that fire pumps get ZERO protection

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Work on an energized disconnect

November 18, 2016

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 was shut off, but with the line side left energized? I asked exactly what he meant? He said our electricians sometimes need to disconnect one of our 480 volt welders for repair or to be serviced. We sometimes have more than one welder on a circuit, so shutting off the

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120 Volt Arc Flash

November 16, 2016

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 no arc flash PPE is required at 120 VAC? READ MORE.           About Jim Phillips, P.E.: Electrical Power and Arc Flash Training Programs – For over 30 years, Jim Phillips has been helping tens of thousands of people around the world, understand electrical power system design, analysis,

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