How to calculate sub panel

[Rdcowart]

So we done a generator on a 400 amp service and everything has passed but the inspector wants me to do a load calculation on the standby panel. I’m trying to figure out how to calculate the load on this panel. I know how to calculate a service load for a home. But how do you calculate a load for the 200 amp sub panel. I’ve done generators before and never had to do this before. Any advice would be helpful thank you.

 

[petersonra]

Just do the same calculation you would for a service but only include the loads on the panel served by the generator

 

[suemarkp]

A trickier part of the sub panel calc is how much square footage is served by the general branch circuits in that panel? Sometimes its easy, as whole rooms or house sections are done. If its an outlet here and there, that can be more difficult to quantify. Will depend if the inspector looks at it for 3 seconds or goes into it in detail.

 

[Npstewart]

I agree that you calculate it the same way as the service but many people on here believe that you can’t use the optional method on sub panels so if he used the optional method then according to some, this wouldn’t be permissible.


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