parallel runs

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smeltz1

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I have a 300 amp panel and i paralleled 3/0 alum wires and a # 4 alum ground wire. The inspector told me i had to run a # 2 alum wire. Can i have some imput please

Thank you
 
im assuming your using 3/0 THHN conductors? the area of a 3/0 thhn conductor is .2679 and you have 2 of them so that equals .5358. that size is close to size 350 MCM but 350 is too small so 400 is the next size up. according to 250.66 a 400 mcm conductor aluminum requires a 1/0 AL conductor or #2 CU* conductor. im assuming this is a main panel?

if this is a subpanel then he is right you need a #2 AL conductor for equipment grounding according to 250.122

*fixed a typo
 
Welcome to the Forum. Heres a bit more to teco's post.

250.122(F) Conductors in Parallel. Where conductors are run in parallel in multiple raceways or cables as permitted in 310.4, the equipment grounding conductors, where used, shall be run in parallel in each raceway or cable.

Each parallel equipment grounding conductor shall be sized on the basis of the ampere rating of the overcurrent device protecting the circuit conductors in the raceway or cable in accordance with Table 250.122.
Click to expand...
 
chris kennedy said:
Welcome to the Forum. Heres a bit more to teco's post.
Click to expand...
Chris points out a very good point. Also I assume your asking about an equipment grounding conductor and not a grounding electrode conductor though I doubt you would be installing the electrode in the parallel raceways.
 
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