Neutral Wire Sizing

[Chris1122]

Why does a residential application with 200 amp service require 4/0 4/0 4/0 with the neutral being the same size as the hot, but mobile home feeder is #2 #2 #4 (smaller neutral) for 100 amp service? Wondering if we can use the mobile home feeder for generator installation with 90 amp breakers? Thanks!

 

[Strathead]

First off, there are cables with a reduced neutral available for 200A as well. But those sizes are rule of thumb. Technically the neutral must be minimum sized per article 220 of the NEC. Normal houses or mobile homes can use those smaller sizes, but an inspection department would be well within their right to ask you to provide calculations to validate that size. You should read article 220 and follow it.

 

[LarryFine]

Why does a residential application with 200 amp service require 4/0 4/0 4/0 with the neutral being the same size as the hot, but mobile home feeder is #2 #2 #4 (smaller neutral) for 100 amp service?

It doesn't. The neutral only needs to be sized for the maximum calculated neutral current, but never smaller than the required grounding conductor.

Wondering if we can use the mobile home feeder for generator installation with 90 amp breakers? Thanks!

Size-wise, yes you can. I use SER cable for generator feeders all the time.

 

[Chris1122]

First off, there are cables with a reduced neutral available for 200A as well. But those sizes are rule of thumb. Technically the neutral must be minimum sized per article 220 of the NEC. Normal houses or mobile homes can use those smaller sizes, but an inspection department would be well within their right to ask you to provide calculations to validate that size. You should read article 220 and follow it.

Thanks for the reply. I will do that.