Neutral sizing

[BPI]

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?

 

[don_resqcapt19]

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.

 

[infinity]

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?

 

[roger]

Along with the other posts see article 220.

Roger

 

[BPI]

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

 

[roger]

Have you looked at the allowed reductions in article 220?

Roger

 

[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

 

[BPI]

Agreed. If I am not mistaken the way I read it, it doesn’t apply in this case?