A friend of mine bought a used hot tub.

Here's the wiring diagram for a 230V permanent power supply: enter image description here

His electrician installed a single 60A breaker in the subpanel. Our best bet based on the wiring diagram is that L1 and L2 going to TB11 and TB12 respectively are probably 240V for the heater and L1 and N going to TB12 and TB1[5] are 120V for the pump and lights.

We were trying to figure out if we could split one of the hot wires to provide 120V without having 2 breakers or if we need to go ahead and get the two breakers.

It seems like electrically it would technically "work," but it also seems reasonable that you would want to explicitly dedicate a breaker to both of those components separately.

So, is there a way of wiring this hot tub on just the single 60A GFCI 240V breaker? Or do we need to replace it with 2 separate breakers?

Edit: Adding information about the breakers

This is the outdoor breaker box with what appears to be a Square D Company 60A breaker in it: enter image description here

  • @Harper-ReinstateMonica It's an outdoor sub panel that needs to be between 10 and 50 feet of the hot tub and has to be visible from the hot tub.
    – D. Patrick
    Jul 27, 2022 at 2:25
  • @Harper-ReinstateMonica it seems important to me too and I was pretty disappointed that those aren't labeled! I actually don't know what those loads are. :(
    – D. Patrick
    Jul 27, 2022 at 2:27
  • Now, what brand is the main panel feeding this subpanel? And what brand is the 60A GFCI breaker that it sounds like will be wasted now? Because I have an idea not to waste it. Jul 27, 2022 at 2:28
  • @Harper-ReinstateMonica I asked him but I think he's asleep. Thanks so far! I'll get back in the morning, preferably with photos.
    – D. Patrick
    Jul 27, 2022 at 2:37
  • 1
    ALright, that's a Square D "QO" normal breaker. Is the main panel also Square D "QO"? (Square D is not enough, they also make HOMeline which is not compatible. The distinctive feature of QO is 2-pole breakers with handle on only one side and the other side blank. Jul 27, 2022 at 16:53

1 Answer 1


I am using 120V and 240V notation. The original question includes 110V, 220V and 230V. For all practical purposes, 110V, 115V and 120V are the same and 220V, 230V and 240V are the same, and the bigger number should be exactly double the smaller number. Current standard convention is 120V/240V.

The diagram is a bit confusing. But as I understand it:

  • Main panel feed to subpanel should be a 50A 4-wire (hot/hot/neutral/ground) feed. Note that the hot colors listed in the diagram do not matter. You can use black and red or two blacks instead of red and blue. Also note that the 100 foot maximum distance between main panel and subpanel really doesn't matter, except in theory with respect to voltage drop. The 50A breaker can be larger (60A is typical) if the wire is sized appropriately.
  • Subpanel has 2 GFCI breakers (20A single 120V breaker, 30A double 240V breaker).
  • Distance from subpanel to hot tub should be as listed - minimum 5 feet (you don't want it in literal reaching and splashing distance) and maximum 50 feet (because it needs to be in line of sight; also should not be around the corner or blocked by bushes or a fence)
  • The heater (most likely) connects to the 30A breaker and gets 240V. The rest (controls/pump?) connects to the 20A breaker and gets 120V using L2 and Neutral.
  • Since L2 is only used for the 30A breaker, it has 20A excess capacity available. So there should be no problem connecting a 20A single 120V breaker to L2 and Neutral. If the subpanel is a typical odd/even left/right stack then you should have the 30A double on one side, the 20A single on the other side and an empty space below the 20A - use that for another 20A breaker.
  • All breakers in the subpanel should include GFCI protection.
  • The 60A breaker is a waste, as Harper already noted, because you can't use it for the 20A 12 AWG or 30A 10 AWG circuits.

Update Based on Image

Based on the image of a 2-space so-called-panel with a double 60A Square D breaker and lots of plastic, it appears you have one a QOE250GFINM:

2 space panel

Picture from Amazon $279 - don't buy one there! Link from Home Depot $145 - don't buy one there either! But don't get one of these at all! (You already have one. This is a warning to anyone else - don't spend 3x the cost of a 6 space panel to get a 2 space panel. That's just backwards.)

The problem is that this is (a) over-priced and (b) 2 spaces. In theory 4 circuits, but you can't use it that way if you need GFCI, which you absolute do. In addition, all the specs I have been able to find indicate that this box is rated for 50A. So even as a feed to another subpanel, it is limited to 50A, which is OK for this application, but not with the currently installed breaker.

You have two options:

  • GFCI feed from the main, new breakers here

GFCI is simply not available in quad breakers. So you can't put a 20A single and a 30A double in this box and GFCI protection. Which means GFCI protection has to be upstream. If your main panel can (legally, technically, not just "shove it in there") use this 60A GFCI breaker, and your feed wire is legal for a 60A breaker, move this breaker to the main panel, replacing whatever is currently there (logically it would have a 60A non-GFCI breaker). Oops, can't do that because this panel is limited to 50A. See if you can swap the 60A for a 50A, or buy a 50A GFCI breaker that matches your main panel. Then install a 20/30/30/20 quad breaker here, which I believe is a QO20303020. Which is (a) ridiculously expensive (yes, online prices (not including Amazon, which is worse) can be much higher than in-person prices at a real supply house, but still crazy, and (b) is apparently really a QO2030 + QO3020 + handle tie - I'm not sure if that would be legitimate for 30A double breaker since that needs to be common trip. But in theory (the experts will chime in if I'm wrong) that should do the trick. And then you would have a 20A single available for your new circuit.

  • Replace the Subpanel

This is what I highly recommend doing. For example, you can get this Square D Homeline 100A 6 space subpanel:

6 space subpanel

for < $50. Square D QO and other brands available for similar price, this is just the first one that came up on Home Depot's web site. Just make sure it is outdoor rated.

Add breakers. Again, putting in a GFCI breaker at the feed will save you money. If that isn't possible or practical, you have 6 spaces here and you will only need 4 even with GFCI - 2 single 20A, 1 double 30A.

  • 1
    We need to figure out which type of breaker is compatible with the main panel, and whether the GFCI is a fit. If so it might not be wasted. Jul 27, 2022 at 2:32
  • @Harper-ReinstateMonica If the 60A is the feed in the main and the wire is large enough, that's fine. If the 60A is a main breaker in the subpanel, that's fine. If the 60A is a branch breaker in the subpanel with everything connected to the one breaker, it is useless. Jul 27, 2022 at 2:34
  • 1
    I assume there's a main panel somewhere with a 50-70A breaker feeding this subpanel. I'm hoping the dunsel GFCI is compatible with it. Jul 27, 2022 at 2:40
  • Good point. Assuming the feed wires are big enough to legally handle 60A. Of course, if the feed wires weren't 60A capable, they definitely would not have put in a 60A branch circuit, right??? Jul 27, 2022 at 2:43
  • 1
    Right. I bet it's at least 55A wire, in which case we can apply the "round up to next available size" rule. Jul 27, 2022 at 4:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.