600A Single Family Residential Service

[jchristopherslice]

I was asked to take a look at a 600A Single Family Residential power distribution system that is under construction. The AHJ said that's required since 600A "qualifies as a commercial service." I've reviewed (what I think are) the relevant sections of the NEC, but didn't find any restrictions on service size for a Single-Family Residential occupancy. I've also scoured the internet and found multiple descriptions of services this large for larger Single-Family occupancies. I wanted to post this here in case I overlooked or missed something. Thank you.

 

[Rock86]

What is your role? Electrician or Engineer? Does your local power company or local codes require this?

 

[hillbilly1]

Not necessarily a commercial service, but may be over the limit on your license, I don’t know about South Carolina, but in Georgia, I believe class 1 (basically a residential license) is restricted to 400 amps and under. That may be what the inspector is getting at.

 

[infinity]

My guess is that he's referring to the 83% rule which ends at 400 amps.

 

[brantmacga]

I’m missing what exactly the inspector is saying is required.

There is no limit though for residential service size. I’ve worked on several homes with 1200A to 2000A 3-phase services.

600A isn’t common but I’ve done a few. Usually install a 600A trans-socket and feed three 200A disconnects. Some of the rural utilities I work with will require a CT cabinet above 400A.


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