FR clothing in Electrical Equipment

[paul32]

Regarding conducting an arc flash study the IEEE 1584 states "Equipment below 240V need not be considered unless it involves at least one 125 kVA or larger low impedance transformer in its immediate power supply"

Cool. I take that to mean a residential load center has no arc flash hazard unless it was supplied by a 125kVA or larger transformer (not likely to ever serve single family homes IMO). Thanks.


For some reason there is no edit buttom for my prior post on this thread. I meant to say impedance of the short, not circuit. Don, my point was the impedance of the SHORT would affect the ACTUAL fault current, even if you precisely knew the AVAILABLE fault current.

 

[zog]

I guess you could make that assumption, but the 1584 does not specifically say that, they are just saying when an arc flash study needs to be done. Does that mean there is no arc flash hazard? I am not sure about that.

The 70E tables for 240V and below has level 0 and 1 for that type of equipment, depending on what task is being performed. If <10kA available, you can reduce by 1 number (HRC).

I think that none of the standards are ever going to say there is no arc flash hazard for liabilty reasons.