Parallel ?

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Ed Carr

Senior Member
Location
way upstate NY
I have two 4" rigid conduits each containing six
500mcm cu conductors. They are feeding a 3 phase
panel with a neutral. My inspector is telling me
that it may not pass. In conduit #1 I have phase A and phase B.
In conduit #2 phase C and the grounded conductor.
I have been going through my book and can't find anything
that says this is a violation. This is the service entrance
from utility transformer. Anyone?

Thanks, Ed
 
Are you reading 310.4(C)-- off the top of my little head I say it's a violation. Well it seems that doesn't help-- sorry.
 
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Ed Carr said:
Dennis & Augie, what about 250.122 F?

Ed
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That applies only to the EGC which if this is a service you will not have.

Unless you can fit into the exception to 300.3(B) that allows isolated phase installations the inspector is correct. You will have to have each phase in each conduit.
 
Besides the already mentioned article sections, we can just apply theory and think about inductive heating. Depending on how the loads are distributed at any period in time, there is a possibility that you could have non canceling current flowing because of the separation in separate metallic raceways which would result in heating of these raceways and conductors.


Roger
 
Ed Carr said:
I think 392.8 D has got me dead in the water.
Could I add 1 grounded conductor to conduit #1?

Ed
Click to expand...

No, there would still be a possibilty of non-cancelling current flowing in both raceways.

Why would article 392 come into play?

Roger
 
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