wire sizing

[sleepy]

1. conductors for the main service is sized at 100%. ex. 400amp service - conductors are 600kcmils. conductors for the secondary panels, not i-line, ex. 150amp main panel (square d nqod panel) 150amp = 1/0 conductors exception sayes you can go one size lower. to #1 awg conductor. where in the nec 2002 does it say this is allowed?
thank you

 

[dana1028]

Re: wire sizing

You might be referring to Table 310-15(B)(6) -

However - this is not an exception; it does not apply to secondary panels, AND you can only use this table for the main power feeds to a dwelling.

 

[russ]

Re: wire sizing

310.15(B)(6) The second sentence says.
"For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panelboard(s)."

 

[steve66]

Re: wire sizing

Also check out 240.4 (B). Although it doesn't really say you can use one size smaller wire, it does sometimes allow you to use one size larger breaker. It often works out to be the same as making the wire one size smaller.

Steve