National Electrical Installation Standards

Standards as High as Your Own

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Friday, January 14, 2022

Question:

Thank you for this NEC question forum. Always picking up NEC knowledge. My question is about the minimum size equipment grounding conductor for a swimming pool pump motor. The branch circuit is a 15-ampere circuit with a 14 AWG copper conductor. The EGC is a 14 AWG and an inspector said that it needs to be a 12 AWG copper minimum. I don't really agree since the EGC generally does not have to be larger than the circuit conductors as stated in 250.122. I'm I correct, or is the inspector correct?

Thanks for your opinion.

Andy Thorson

A

Answer:

Hi Andy,

Thanks for the comments and the question. The inspector has made the correct call on this one. Remember the NEC arrangement and application as governed by Section 90.3. The rules in Chapter 6 can modify the general rules in chapters 1 through 7, sometimes to be more restrictive, as is the case here. Section 680.21(A)(1) which indicates that wiring methods installed in the corrosive environment described in 680.14 shall comply with 680.14(B) or shall be type MC cable listed for that location. Wiring methods installed in these locations shall contain an insulated copper equipment grounding conductor sized in accordance with Table 250.122 but not smaller than 12 AWG. The restrictions are that the EGC must be insulated copper and it must be sized at 12 AWG minimum. The reasons are relatively clear in the first sentence in this provisions which eludes to corrosive environments. The restrictive sizing rule is related to corrosion concerns rather than capacity in this case.

Hope this is useful.  

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