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Can load side disconnect be smaller than "sub" panel disconnect?

Can load side disconnect be smaller than "sub" panel disconnect?

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Old 11-02-09, 01:40 PM
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Can load side disconnect be smaller than "sub" panel disconnect?

I recently bought a 100A meter/main disconnect, but it seems no one readily sells 100A panels, so I bought a 125A Square-D HOM style panel. This is all to wire a newly constructed storage building. My question is: can the interior panel "main breaker" be larger than the outside service disconnect? I will probably have one 240v outlet inside just in case, but don't really anticipate much loading -just lights & misc hand tools.
 
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Old 11-02-09, 01:50 PM
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The main breaker on a subpanel serves primarily as a disconnect switch. Protection is provided by the breaker at the main panel so the answer is yes the subpanel breaker can be larger. It is just a switch in this configuration.
 
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Old 11-02-09, 02:42 PM
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Originally Posted by ray2047 View Post
The main breaker on a subpanel serves primarily as a disconnect switch. Protection is provided by the breaker at the main panel so the answer is yes the subpanel breaker can be larger. It is just a switch in this configuration.
Thanks Ray. So just to clarify, the interior 125A main breaker is basically just an expensive switch for that panel and the overload protection is handled by the exterior 100 amp main disconnect breaker/switch?
 
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Old 11-02-09, 03:06 PM
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Originally Posted by bushdude View Post
Thanks Ray. So just to clarify, the interior 125A main breaker is basically just an expensive switch for that panel and the overload protection is handled by the exterior 100 amp main disconnect breaker/switch?
Yes.

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Old 11-02-09, 03:07 PM
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Yes that is correct. Overcurrent protection is provided by the smallest breaker in the feeder.
 
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Old 11-02-09, 03:36 PM
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Also remember that you will be able to size your wire based on that 100 amp breaker and not the 125 amp in your panel box.

Thanks!
Jim

 
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