100 amp 240v s. ph. feed in 2 conduits?

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bclumen

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I feel silly asking this but I don't know and didn't find the answer in the NEC. Can a 100 amp 240 volt feed be installed through 2 conduits instead of just one?
Length of run 350' - wire & size: 2 #2, 1#4, 1#6 all copper THHN
4 existing 1" PVC conduits already installed by others.

Wher in the NEC can I find this out?
 
bclumen said:
I feel silly asking this but I don't know and didn't find the answer in the NEC. Can a 100 amp 240 volt feed be installed through 2 conduits instead of just one?
Length of run 350' - wire & size: 2 #2, 1#4, 1#6 all copper THHN
4 existing 1" PVC conduits already installed by others.

Wher in the NEC can I find this out?
Click to expand...

No, the NEC allows conductors 1/0 and larger to be paralleled with a few exceptions.

See 310.4
 
bclumen said:
Wher in the NEC can I find this out?
Click to expand...
See 300.3(B)(3) and 300.20(B). This is regarding the separating of conductors into more than one raceway.

IIIRC however, if these are service conductors, it's a no go. As all service conductors have to be in the same conduit unless they are paralleled...
 
bclumen said:
I feel silly asking this but I don't know and didn't find the answer in the NEC. Can a 100 amp 240 volt feed be installed through 2 conduits instead of just one?
Length of run 350' - wire & size: 2 #2, 1#4, 1#6 all copper THHN
4 existing 1" PVC conduits already installed by others.

Wher in the NEC can I find this out?
Click to expand...


Without doing the calcs, it looks like you're pretty close to getting them in one conduit, maybe a little over the 40%. You can reduce the #6 to #8 if it is the EGC.
 
wirebender said:
Without doing the calcs, it looks like you're pretty close to getting them in one conduit, maybe a little over the 40%. You can reduce the #6 to #8 if it is the EGC.
Click to expand...
Gotta watch that "upsized conductor" rule. How about using a bare EGC?
 
Even a bare #6 EGC still puts him over.

Do a load calc to see if you can drop the neutral to #6. If you can, your conduit fill will be exactly 40%. Otherwise, you'll have to drop your phases to #3 which will also allow you to drop your EGC to #8. This definitely won't help with VD at 350' though.
 
Thank alot everyone. This was what I needed. To follow up - this is a typical ultra high end residential swimming pool project where the client doesn't want to see his equipment and the pool co. has little comprehension of all that's affected when they agree to setting the equipment that far away. I'm no plumber but I think the extended distance would play a major role in the effictivness of the hydraulics.

I am getting the job. I will charge a hefty fee to install a 1.5" PVC in a trench they dig.

Now I am dealing with branch circuit runs in excess of 450' - fun!!

Thanks again!
 
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