sub panel breaker size


  #1  
Old 11-23-20, 01:46 PM
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sub panel breaker size

California, USA

Setup: 200 amp main panel feeding a 100 amp second panel. In the main panel is a 100 amp 220 volt breaker. Four wires go over to the sub panel, hot red and hot black from the 100 amp breaker. Neutral and ground from their respective locations. Neutral and ground are kept separate in the sub panel.

I donít know the proper names of the two hot wires but I saw a drawing in the sticky section here using red and black so use that.
Question

Presume I turn some 110 volt stuff on in the sub panel and draw 80 amps from hot red. Nothing on hot black. Then more 110 stuff is turned on and draws 80 amps on hot black.

Am I correct in presuming this will be fine?
 
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Old 11-23-20, 02:08 PM
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Yes. *
 
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Old 11-23-20, 05:53 PM
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I don't know why the * after the Yes, but as I see nothing else in the reply I will take that as an unqualified yes.
Thank you for your time.
 
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Old 11-23-20, 06:30 PM
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When you set up a panel you try to balance the loads as equally as possible on the A and B (or red and black) legs. It's not always easy. For example.... if you were connecting 120v heat.... put some on each leg. 240v loads are automatically balanced on both legs.

Any imbalance between the legs is handled by the neutral.
If you were to check the amperage draws and saw 80A on one leg and 20A on another..... you'd try to see if anything could be moved. Keep in mind the breakers alternate from A leg to B leg down the row.
1 would be A ...... 2 would be A
3 would be B ...... 4 would be B
5 would be A ...... 6 would be A
etc.
 
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Old 11-26-20, 07:27 PM
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The * was at the end of a bunch of spaces because you can't have a response with less than 25 characters. Why, I don't know. Stupid requirement.
 
  #6  
Old 11-28-20, 08:57 AM
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Presume I turn some 110 volt stuff on in the sub panel and draw 80 amps from hot red.
I bet you can't get to 80 amp short of plugging in electric heaters trying to prove that you can.
 
 

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