Sub Panel Size

[krussell@scs-usa.com]

I saw this on another forum and I don't see any code where this is addressed.

The issue was you have a 100 Amp service to a dwelling coming into a 100 Amp Load Center.

The Home Owner want to take 80 amp service to the garage. So He install a 80 Amp Breaker in the load center then feeds a seprate load center in the garage (a "sub panel")

His Post was

I talked to an electrician about a project that I'm planning--basically the same thing--a sub panel for the garage. His comment was that the sub panel breaker can only be up to 80% of the main panel. So a 100amp panel can supply up to a 80 amp breaker. a 200 up to a 160 amp sub panel. I'm probably going to end up with a 125 amp sub running from the 200 amp main.....


The Question:

So is there a code that says the MAXIMUM size of a "sub panel" is 80% of the Main Resiential service.

I dont see it in the NEC 2008
AM I missing it?

 

[billsnuff]

215.5(a)(1)(2)(3)

 

[bluesmoke...oops]

215.5(a)(1)(2)(3)

In the 2008 NEC 215.5 doesn't have sub headings.

 

[Dennis Alwon]

In the 2008 NEC 215.5 doesn't have sub headings.

I bet bill means 215.2 (A)(1)(2)(3)

 

[Dennis Alwon]

The Question:

So is there a code that says the MAXIMUM size of a "sub panel" is 80% of the Main Resiential service.

I dont see it in the NEC 2008
AM I missing it?

You are not missing it. I can install 100 amp breaker in the panel with the proper feeder wider if the panel allows that, as long as the total calculated load is less than 100 amps. Now a 200 amp panel, at least the ones I use, will only allow a maximum 125 amp breaker on the buss. I rarely use a 100 amp panel except as a sub panel so I am not certain. It is not an NEC issue but rather the manufacturers specs.

 

[billsnuff]

I bet bill means 215.2 (A)(1)(2)(3)

Bad fingers! Bad fingers!

Thanks Dennis....