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have a Square D breaker box that's almost full. Need to add a 240V 60A (technically 70a for length of run) for a swim spa. Have a quad breaker at top which is 20/30/30/20 (used for outside AC). Other 240v include oven, dryer and the other AC unit.

Would like to consolidate or otherwise add a breaker that is up to code that serves existing needs and adds the needed 240V / 60A capability. Thank you!

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  • Best bet would probably be to add a sub panel near the main, and give space.
    – crip659
    Commented Aug 28, 2022 at 18:02
  • How many amps/watts does the swim spa actually pull, and how many square feet is your house? Also, how many KW is the oven, and how many amps is the AC rated to pull? Finally, what's hooked up tot he "spare" breakers at the top? Commented Aug 28, 2022 at 21:03
  • @ThreePhaseEel the swim spay calls for a 60a breaker but should actually use a bit less. Confirmed nothing on the spares. I can find out on the oven and AC but the spa itself I understand has to be on a dedicated circuit.
    – Matt
    Commented Aug 28, 2022 at 23:46
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    @Matt -- can you get us an actual nameplate amps for the swim spa, not just a breaker handle rating? Can't do the load calcs without it...and yeah, we'll need that square footage + info on the oven+AC to do that as well Commented Aug 29, 2022 at 1:19
  • @ThreePhaseEel Hope this helps: Sq feet: 3400; Oven: 33a (breaker underrated? never had a trip - double oven); AC: 19.8a (two - both rarely run both but sometimes); Dryer - not used (gas); Swim spa - manufacturers don't show those details readily but I understand that the 60 amps are primarily for starting current and operating current about 33a
    – Matt
    Commented Aug 29, 2022 at 23:04

2 Answers 2

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To just consolidate, I'd replace the top quad breaker with a 15/30/30/15. Use the two 30's for the AC same as before and move the GD and DW to the top 15's which are shown as spares. Remove the 15 double pole and use the empty space for your 60 amp double pole breaker to feed the spa or to feed a sub panel by the spa.

You'll need to do some load checking to make sure your panel can handle the additional load

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  • Thank you! Very helpful
    – Matt
    Commented Aug 30, 2022 at 0:30
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You should be good to go on service size

I ran a quick load calculation with your square footage, 4 kitchen + 1 laundry circuit (counting GD+DW as one SABC and treating the fridge as lighting load), and stated loads for the oven and A/C units, and came up with just under 110A @ 240VAC, so you have plenty of room for your swim spa.

With that said, you'll want to plan ahead now to avoid future headaches

Your service entrance panel appears to be a version of the Square-D SC2040M200C, which means that you have to plan a bit differently for upgrades than folks with regular panels, as your main panel only has a single column of breakers, and is limited to 100A breakers maximum by the limited wire bending space adjacent to that column of breakers.

So, in order to provide enough room for a future subpanel to handle most of the lighting loads, I'd not only swap the top quad breaker to a HOMT215230 and move the disposal and dishwasher circuits there for the time being, but take the opportunity to either remove the dryer circuit, or consolidate it with the oven circuit by replacing the oven breaker with a HOMT230230. This way, you not only free up room for your swim spa, but a spare pair of full-width slots for feeding a subpanel in the future (you'll need it if you want to retrofit AFCIs, if nothing else).

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  • Thank you! Very helpful!
    – Matt
    Commented Sep 1, 2022 at 2:32

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