Using Table 310.15(B)(6)

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JohnJ0906

JohnJ0906

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Baltimore, MD
Is it permitted to use Table 310.15(B)(6) if I am paralleling conductors?

If, for instance, if I was running a 600 amp feeder to a dwelling, could I parallel 250 kcmil CU? (250 CU is listed for a 300 amp residential service)

I don't see anything prohibiting this in either 310.15 or 310.4.

Someone asked me if this was allowed, and, after not finding anything in the NEC myself, I thought I would throw it out for discussion.
 
I'll bite. :D

I say it's not permitted, since the table doesn't provide for parallel conductors. Many esteemed people here would disagree with me. :)
 
In the text before the table it says----- conductors,as listed in Table 310.15(B)(6),

shall be permitted as 120/240-volt 3 wire, single phase service entrance conductors.

That pretty much limits it to the table.
 
John, I agree with the other but also remember if you have a 400 amp meter base (320 continuous) with 2- 200 amp panels then you cannot use T310.15 (B)(6) either
 
Proposal 6-74 in the 95ROP was to prohibit the use of the reduced wire sizes in parallel. Panel 6 rejected the Proposal with this statement: "Conductors 1/0 and larger are permitted to be paralleled by section 310-4. This would apply to Note 3." Note 3 in the 1993 code was what is now 310.15(B)(6), however neither the proposal nor the panel comment addressed the issue of services over 600 amps.
 
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