Service Equipment

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danilo

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hi guys,

need again your help..could i use for service equipment our available 1000A,3p CB if the service entrance conductor ampacity is only 750A (2sets of 3-500mcm THW)? expected continuous load is only 600A..is there NEC provision on this?sorry for this but its NEC 1984 i have on hand..havent bought the new version yet.

appreciate your valuable comments..thanks
 
Re: Service Equipment

I do not believe a 1,000A OCD would be permitted even though the load is less than the rating of the service conductors.

Section 230.90 (NEC 2002) states the rating of the protection device shall not be greater than the ampacity of the conductors. The only exception you could use is #2, which allows the next higher standard OCD when one doesn't conform to the ampacity of the conductors.

So for your particular installation:

500 kcmil @ 75 degrees = 380A x 2 = 760A. Next size up is 800A.
 
Re: Service Equipment

thanks for the reply guys..i really appreciate it.

i just avoid buying another OCD and instead proposed to use the 1000A OCD..However, since its a violation of the NEC Code, i just have to purchase 800A as suggested by the experts.

have a copy of the new code actually, but i misplaced it somewhere..ill buy new one soon.

Gracias!
 
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