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#101171 02/14/07 12:22 PM
Joined: Sep 2004
Posts: 138
R
royta Offline OP
Member
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).]

2017 / 2014 NEC & Related Books and Study Guides
#101172 02/14/07 12:49 PM
Joined: Jan 2001
Posts: 1,044
Tom Offline
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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


Few things are harder to put up with than the annoyance of a good example.

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