Neutral sizing

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B

BPI

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Contractor
I’m sure this has been a topic in a previous thread but if I have #8’s for a 40 amp feed to a sub panel can I downsize the neutral to a #10?
 
You need to know the neutral load from the panel. Its minimum size for the a 40 amp feeder would be 10 AWG copper, but the neutral load could require the neutral to be full size. You need to do do a load calculation for the neutral load.
 
As Don stated the load calculation also calculates the neutral size but for a 40 amp feeder why do you want to reduce the neutral size?
 
Along with the other posts see article 220.

Roger
 
This is for a project that’s already been done we have a pool sub panel with 2- 240 motors with a draw of 26amps And 2-120 circuits with a draw of 5 amps. The inspector says the #10 neutral is not sufficient and needs to be a #8
 
Have you looked at the allowed reductions in article 220?

Roger
 
BTW, I'm not trying to say the inspector is correct, but if you're going to challenge him have your Ducks in a row.

Roger
 
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