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#101171 - 02/14/07 08:22 AM main breaker or not?
royta Offline

Registered: 09/03/04
Posts: 136
Loc: CA
I've always been confused on whether I need a main breaker for a sub-panel.

Situation 1 - Residential main service with a feeder breaker feeding sub-panel mounted within or on home. Is there a situation when the sub-panel needs a main?

Situation 2 - Residential main service with a feeder breaker feeding sub-panel mounted on seperate structure or somewhere else on property. Sub-panel only needs a main IF there are more than six breaker handles (twin counts as two handles), correct?

Situation 3 - 400A residential main service with first 200A main supplying the built-in distribution. Second 200A main feeding 20/40 sub-panel located on other side of house. Sub-panel has conduit provisions to supply future sub-panels located on other structures or areas of property.

Situation 4 - Commercial main service on exterior of building. Individual feeder (main) breakers feeding sub-panels located in each commercial suite. Every sub-panel I've ever seen in these situations always has a main breaker.

[This message has been edited by royta (edited 02-14-2007).]

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#101172 - 02/14/07 08:49 AM Re: main breaker or not?
Tom Offline

Registered: 01/01/01
Posts: 1069
Loc: Shinnston, WV USA
1. Not needed

2. Needed if six disconnects are exceeded. A 2 pole breaker is one breaker. If by twin you mean a breaker with two separate handles, then the twin counts as two.

3. Not needed

4. Not needed
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