Do ___________ if service is > 120/240V, 800 amps, fed by a 150 KVA transformer

[Electron_Sam78]

Has anyone come across a statement in the NEC or NEC Handbook that gives this limit (it doesn't have to be done if service is 120/240V, 800 amps, and fed by a 150 KVA transformer or less) on a recommended or required activity? I'm not sure what activity though. I thought it was doing an arc flash hazard analysis but the NEC doesn't cover that. Could that have come from NFPA 70E? Maybe it had to do with short circuit calculations but I'm coming up empty looking through the NEC Handbook. Did I dream this?

 

[jumper]

May be something to do with 240.4(C). IDK

(C) Overcurrent Devices Rated over 800 Amperes. Where
the overcurrent device is rated over 800 amperes, the ampacity
of the conductors it protects shall be equal to or
greater than the rating of the overcurrent device defined in
240.6.

 

[jumper]

130.3 Exception(1) in 70E has some numbers that may help answer your question.

 

[Electron_Sam78]

I actually don't have a copy of 70E...

 

[jumper]

I actually don't have a copy of 70E...

Go to the NFPA web site, join for free, and you can view it online. I did.

http://www.nfpa.org/aboutthecodes/list_of_codes_and_standards.asp?cookie_test=1

 

[jumper]

Found a copy of it. 2009 NFPA 70E 130.3

Exception No. 1: An arc flash hazard analysis shall not be required where all of the following conditions exist:
(1) The circuit is rated 240 volts or less.
(2) The circuit is supplied by one transformer.
(3) The transformer supplying the circuit is rated less than 125 kVA.

 

[Electron_Sam78]

Got it,

NFPA 70E section 130.3 Exception No. 1: An arc flash hazard analysis shall not be required where all of the following conditions exist:

(1) The circuit is rated 240 volts or less.
(2) The circuit is supplied by one transformer.
(3) The transformer supplying the circuit is rated less than 125 kVA.

That could be what I was looking for. It sounds a lot like it. I'm not sure where i got the 150 KVA and 800 amps.

Thanks for the help jumper .

 

[jumper]

You are welcome. I had fun finding the info.

 

[zog]

Found a copy of it. 2009 NFPA 70E 130.3

Exception No. 1: An arc flash hazard analysis shall not be required where all of the following conditions exist:
(1) The circuit is rated 240 volts or less.
(2) The circuit is supplied by one transformer.
(3) The transformer supplying the circuit is rated less than 125 kVA.

And that comes from IEEE 1584

 

[jumper]

And that comes from IEEE 1584

Where have you all been? This was a question for you, jim d or rich from the start.