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Technical Articles

Arc Flash Forum Update

2017 NEC 240.87 Instantaneous Trip

October 18, 2016

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 energy must be provided. The 2014 Edition of the NEC provided a list of methods which included: zone-selective interlocking, differential relaying, energy-reducing maintenance switching and energy-reducing active mitigation systems or an approved equivalent means. The device’s instantaneous trip function was excluded from the list. The 2017 Edition of the NEC

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Low Fault Current on Utility System

October 14, 2016

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 with about 92A fault current at the end of the run. The run is 7.5 miles with AAAC Ames and a 40K fuse on the txf secondary. The only fusing is on the secondary side of a stepdown transformer (13.2kv primary). Trying to use ArcPro and the fault current is

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Easy way to get a series combo rating – sometimes??? Maybe?

October 13, 2016

Hi all. As I continue to slog through my list of 104 buildings on campus I need to do studies on I discovered yet another over-dutied situation yesterday. Common scenario, 208Y/120V “service” with 15-ish kA available at the main panel and a 100A MLO branch panel right next to it (very short feeder) with 14-ish kA available. Square D QOB (10KAIC) branch breakers. No main breaker. The main panel is Cutler Hammer so no series ratings exist between CH and

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Do you use equipment/methods based on IEC Standards?

October 11, 2016

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 of IEC TC78 Live-Working which has 35 standards/publications including Arc Flash Protection. The IEC prepares and publishes International Standards for all electrical, electronic and related technologies. Since the Arc Flash Forum is an international community, here is this week’s question: Do you (your company) use any electrical equipment/methods based on

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Arc Rated Clothing Causing Health Effects

October 7, 2016

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 of dermatitis. This seems to be happening in hot locations and when the employee works hard enough to work up a sweat. Our company has taken the approach that we are to wear arc flash protection at all times even there is no risk of danger (sitting in a control

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Air Conditioner Motor Contribution

October 6, 2016

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 under construction!). I’m wondering if most people model the various motors separately (compressor, fan, other?), or do you leave them modeled as one. Also, as some of the motors may be buried in the equipment, do you always verify RPM, service factor, FLA, and other motor nameplate data? I’m not

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Lock Out / Tag Out Simple vs. Complex

October 5, 2016

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 – A complex LOTO has significantly more requirements. Here is this week’s question: Have you ever performed a complex LOTO? Yes No ANSWER   About Jim Phillips: Electrical Power and Arc Flash Training Programs – For over 30 years, Jim Phillips has been helping tens of thousands of people around the world,

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IEEE 1584 and Overdutied Breakers

October 4, 2016

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? READ MORE _________________ Barry Donovan, P.E. www.workplacesafetysolutions.com

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Replacing AF Labels

September 30, 2016

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 very rugged and difficult to peel off. Anyone have experience with tools or techniques that make the old label removal more time efficient?I’m not a huge fan of sticking new labels on old labels unless it’s unavoidable, I think it looks sloppy unless the two labels were perfectly lined up.

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Aluminum vs. Copper IE differences

September 29, 2016

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 solid to liquid) and aluminum is exothermic (releases energy when converting from solid to liquid). They claim that due to these differences equipment with internal aluminum construction has a much greater potential for destructive energy release during an arc fault vs. copper construction. Does anyone account for this difference in

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