Arc Flash / Fault Current Calcs

[jimioy]

About figuring fault current values on secondary distribution feeder circuits - I have a question. When plugging the type of conduit (PVC, RMC, etc.) into the equation do I enter steel or PVC if the conduit run has steel elbows only and mostly PVC?

I'm having an engineering outfit do the coordination study on our distribution system which is just a 12470V seriesed grid with load break elbow style junction boxes (not true sectionalizers) which are tapped to feed, typically, 480V secondary pad mount transformers for facility power. They are covering our system just to the service main to each facility. My small shop will take it from there and do all the MCCs, Panel and Switch boards, disconnects, etc.

I know what fault current is but am not clear on "bolted"???

 

[dpc]

If it's mostly PVC, use PVC. A bolted fault just means a zero impedance fault. Like you "bolt" a piece of bus across the three phases and throw the switch (don't try this at home).

 

[jimioy]

dpc - Thanks for the response. That's what I thought on the pvc issue and I get the term bolted now...Thanks

Jimi Young - civilian
184th CES/Electrical Shop
Ks Air Nat'l Guard
McConnell AFB, KS