Conductors in Parallel

[jedidia]

310.4 Conductors in Parallel
(b) The ampacity of each individual conductor is sufficient to carry the entire load current shared by the parallel conductors.

Is the above code for both AC and DC circuits run in parallel?

Thanks,
Jed

 

[Dan coulstring]

Yes

(H) Conductors in Parallel.
(1) General. Aluminum, copper-clad aluminum, or copper
conductors, for each phase, polarity, neutral, or grounded circuit
shall be permitted to be connected in parallel (electrically
joined at both ends) only in sizes 1/0 AWG and larger where
installed in accordance with 310.10(H)(2) through (H)(6).

 

[subinstaller]

For DC installations, I do not believe this NEC spec is applicable.

AT&T, Lucent, Nortel (now Ciena), Verizon to name a few do not size DC power cable runs to this spec in the US. They all calculate the number of DC conductors required where the total number of conductors is what's needed to carry the load. They are of course taking ampacity into consideration, but not where each individual conductor can carry the entire amp load. It's the sum of the conductors (sum of the circular mils) to carry the amp load.

I'll need to dig into the NEC and see if there's an exception note somewhere, but I find it hard to believe all these companies are violating the NEC sizing DC conductors.

 

[don_resqcapt19]

That is part Exception No. 1 and that part is only saying that where the each conductor is large enough to carry the fully load you can parallel conductors that are smaller than 1/0, however to parallel conductors smaller than 1/0 you also have to comply with conditions (a) and (c) as well as condition (b) that is quoted in the OP.

 

[shepelec]

Basically this is allowed for voltage drop under the exception.

 

[Dan coulstring]

For DC installations, I do not believe this NEC spec is applicable.

AT&T, Lucent, Nortel (now Ciena), Verizon to name a few do not size DC power cable runs to this spec in the US. They all calculate the number of DC conductors required where the total number of conductors is what's needed to carry the load. They are of course taking ampacity into consideration, but not where each individual conductor can carry the entire amp load. It's the sum of the conductors (sum of the circular mils) to carry the amp load.

I'll need to dig into the NEC and see if there's an exception note somewhere, but I find it hard to believe all these companies are violating the NEC sizing DC conductors.

I don't think they are governed by the NEC 90.2(B)(4)

 

[subinstaller]

thanks for clarifiying Dan