Residential Service Sizing

[mgardner]

So I've calculated the loads for each apartment in a multi-family building I'm working on using the Option Calculation Method in Section IV of Article 220. I get a load of 25,816VA at 240V = 108A.

Do I specify a 110A main or a 125A main?

 

[Dennis Alwon]

I have never seen a 110 amp main so I bet you would pay an arm and a leg if it is even available as a main panel. Go with 125 amp or 150 depending on which is cheaper. I would assume the 125 amp is but different areas use different size mains.

Here a 150 amp MB panel cost way more than a 200 amp panel. You never see 150 amp services. 200 is the norm.

 

[Npstewart]

I would definitley at least go with a 150A, if they want to add a jacuzzi tub or something, it would be almost impossible if they had a 125A panel with a load of 108 amps.