I have a small existing pool house (built 1988) that has electrical service ran to it from the house distribution panel. Two breaker and two separate sets of wires go to the pool house, 240 single phase power for the pool pump (on one 20 amp breaker) and 120 single phase to provide electric to various outlets, fan, etc. (on 15 amp breaker). The services is buried. I would like to put a subpanel in the pool house to have more local control over the loads. So, if I put a subpanel in the pool house, can I combine (20 amp + 15 amp) the feed on the main bus bar and install breakers? I have never seen this before, but if you combined the hots, neutrals, ground, bare ground, in the subpanel, wouldn't this maintain the same current flow through each lead?

  • Not considering other factors, typically 20 ampere circuits use 12 AWG copper, while 30 ampere circuits require 10 AWG. Since your going to have to run new wires anyway, you might want to think about going even bigger, and giving yourself some future expansion possibilities. When installing secondary panels, I often recommend 70 - 100 amperes depending on the situation. While you might not need that capacity now, you might be thankful for it in the future.
    – Tester101
    Jun 28, 2015 at 13:50

1 Answer 1


National Electrical Code says that you cannot connect conductors 1 AWG or smaller in parallel (310.10(H)). Since it's not likely that the conductors between your buildings are larger than 1AWG, you cannot do what you want.

What you can do, is install a new larger double pole breaker in the main panel. Then install a new set (4 conductors) of larger conductors between the buildings, to feed a secondary panel in the pool house. Then you can feed your branch circuits from the panel in the pool house.

The size of the breaker in the main panel, and the size of the conductors between the buildings will depend on what size service you want to supply to the pool house.

  • OK. The problem with installing the larger breaker is the wires from the main house and the pool house are buried. I presume I could determine the lateral wire gauge and determine if it is of adequate size to increase the amps. Does a 20 amp circuit and and 30 amp circuit bump you down in gauge? I would assume it does, but haven't looked yet.
    – user38927
    Jun 28, 2015 at 13:40
  • @BradRodgers Basically you can't do what you want without running new cable, or having the entire building running off the cable for the pool pump. ( that is the whole building will be limited to 20 Amps, which is less than you have now ) Jun 29, 2015 at 15:45

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