Branch CB Smaller than Main CB of Subpanel

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Electriman

Senior Member
Location
TX
Good morning,

I just have a quick question. Can I feed a subpanel with a main CB of 60A with a 30A branch circuit breaker in the main panel in order to run #10 cable to subpanel? The load of the subpanel is not more than 10 A so a 30A breaker should be able to support the load.

Thanks in advance.
 
Sure, so long as the conductors are properly protected. But why bother having a 60A main in the sub panel then? Waste of money unless it’s something you already have and want to use.
 
Yes. If there are no other Taps off of the 30A branch circuit breaker OR you do not care about selective-coordination.

Basically, in this scenario, it is always the branch circuit breaker in your Main panel that is going to operate for any faults/overloads downstream of your subpanel.
 
sgayam said:
Yes. If there are no other Taps off of the 30A branch circuit breaker OR you do not care about selective-coordination.

Basically, in this scenario, it is always the branch circuit breaker in your Main panel that is going to operate for any faults/overloads downstream of your subpanel.
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Which may end up being a significant nuisance if the main panel is far away...
 
Jraef said:
Sure, so long as the conductors are properly protected. But why bother having a 60A main in the sub panel then? Waste of money unless it’s something you already have and want to use.
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It is a legacy panel. We are not supposed to touch it.
 
Totally fine. The other situation where this is common is when a cheap panel with a main breaker is less expensive than a main lug panel
 
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