320A meter base - panel sizes

jeff48356

Senior Member
If I install a 320A meter base (with service conductors rated for such), would I be allowed to install two 200A panels in the basement, or would one of them need to be a 100A (or 150A)?

Since 2/0 copper (or 4/0 aluminum) is used for 200A service per the 83% rule, what would be the sizes of CU and AL conductors to be used to feed a 320A? Just wondering since 200A is the largest I've ever installed.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
A 320 amp meter base is really a 400 amp base non continuous. The 320 is for continuous loads (400x .80= 320).

So yes 2- 200 amp panels are allowed. However, since neither panel feeds 100% of the dwelling load then you cannot use the 83%. You would need to use the tables of 310.15(B)(16)

4/0 could be used if you are not over 180 amps calculated load in either panel. I assume you can take advantage of the 75C column for either pipe of SE cable.
 

jeff48356

Senior Member
A 320 amp meter base is really a 400 amp base non continuous. The 320 is for continuous loads (400x .80= 320).

So yes 2- 200 amp panels are allowed. However, since neither panel feeds 100% of the dwelling load then you cannot use the 83%. You would need to use the tables of 310.15(B)(16)

4/0 could be used if you are not over 180 amps calculated load in either panel. I assume you can take advantage of the 75C column for either pipe of SE cable.
OK, so I would probably use 3/0 THHN copper for the feeds to each panel (2/0 for neutral). What size conductors on the line side from the POCO would most likely be used?
 

kec

Member
Location
CT
Are you running the line side of the meter? Power company usually does that
Here in CT we have a smaller POCO that covers a county that requires we supply the underground service wire. They will assist in pulling conductors in conduit.
I will provide 350 MCM Al for a 320 meter.
 

kwired

Electron manager
Location
NE Nebraska
OK, so I would probably use 3/0 THHN copper for the feeds to each panel (2/0 for neutral). What size conductors on the line side from the POCO would most likely be used?
Since you have multiple service disconnecting means, NEC only requires you to run conductors with enough ampacity to carry the calculated load.

As mentioned with some POCO's, 4/0 aluminum may be what you get. Quite a few probably would pull 350 aluminum to this though.
 
Top