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Wednesday, July 7, 2021

Question:

Hello CQD Friends,

300.17 offers a subjective provision to what size of conductor may share the same conduit. Is there a clear cut rule for what size of conductors are prohibited from sharing the same conduit? Just to make the point with an extreme hypothetical - can #14 control wires share the same 150' / 270 degree bend conduit with 750mcm conductors? Probably not, but where is the line? It seems that as we get closer to the same #14 wires sharing with say #1/0 that discretion is simply up to the installer. If the wires make it in without damage then it's okay no matter the size?

Thanks for your work,

Brett McClure

A

Answer:

Hi Brett,

The NEC does not place a specific size limit on the grouping of larger conductors with smaller ones in the same raceway. The conductors must be installed in a manner that renders them accessible (as applied to wiring methods). 

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