320 service feeding two subpanels

[merlinmc]

320 Service will feed two 200 amp subpanels (they will each have 160 amps each). Can each subpanel be feed with a 2/0-2/0-2/0-1 copper wire or would you recommend something else? Subpanels will be wired to a 22kW generator with smart switch and load shedding. Thanks.

 

[augie47]

Since you have two service panels, neither ONE is actually carrying "all loads associated with the dwelling" as stated as a requirement in 310.15(B)(6) {'08 Code ref} therefore, although it is often allowed, the use of a 2/0, 175 amp rated conductor, is not Code acceptable using 200 amp breakers.

 

[merlinmc]

175 amp breakers

175 amp breakers

Thanks. Could I use 175 amp breaker in each of subpanels?

 

[augie47]

IMO, Yes

 

[Dennis Alwon]

Thanks. Could I use 175 amp breaker in each of subpanels?

That will cost more than a 200 amp main breaker panel with 3/0 copper--unless it is a long run. What size breaker will feed the sub panels???

 

[merlinmc]

Runs and breakers

Runs and breakers

Run is about 50' horizontally and has to go up into the joist space and then back down, so around 60' total. Each subpanel will have a 175 amp breaker and 160 amps of circuits. I suppose 4/0-4/0-4/0-2/0 alumnium would be another alternative to feed these subpanels from the 320 amp main. Thanks.

 

[augie47]

Run is about 50' horizontally and has to go up into the joist space and then back down, so around 60' total. Each subpanel will have a 175 amp breaker and 160 amps of circuits. I suppose 4/0-4/0-4/0-2/0 alumnium would be another alternative to feed these subpanels from the 320 amp main. Thanks.

From that description you will have to have OCP ahead of the sub-panels. With that OCP properly sized, the sub-panels don't even need a main, and if they have one it can be any size equal to or above the service OCP or allowable by tap rules.

 

[Dennis Alwon]

From that description you will have to have OCP ahead of the sub-panels. With that OCP properly sized, the sub-panels don't even need a main, and if they have one it can be any size equal to or above the service OCP or allowable by tap rules.

That is what I was getting at. I was asking the OP what size breaker is feeding the sub panel not what size breaker is in the sub panel.

 

[Dennis Alwon]

BTW, a 320 amp meter is a 400 amp meter base. It is 320 amps of continuous load or 400 non continuous load. Of course you don't have to use the entire 400 amps.