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Steve G.
Steve G., Electrical Engineer
Category: Electrical
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Experience:  Spent 20 years as an Electrical Engineer, designing electrical plans and specifications.
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I have a swimming pool and hot tub at home that use a 5.5kW

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I have a swimming pool and hot tub at home that use a 5.5kW 147000 BTU heat pump to heat both. For the hot tub, the heat pump doesn't work so well below ambient air temps of 57F. Therefore, on cold nights the hot tub struggles to stay above 96F.

To keep the tub toasty I plan to add an 11kW electric spa heater (CSPAXI11). The heater I’m planning on buying has an 220V 3 wire hook up. The install instructions recommend a 2 pole 60A breaker at the main panel routed through 4 wire (6 AWG) to a local pool area spa sub panel (as per code), then through a 60A GFCI breaker to the new spa heater.

I already have a pool sub panel breaker box next to the pool equipment. It's fed by a 60A breaker at the main panel and the wire from the mains to the pool sub panel looks like 4 AWG (looks bigger to me than 6 AWG but I can’t see any writing on the insulator yet). The feed is routed along the side of the house in grey plastic pvc conduit to the pool sub panel.

The problem is that the pool sub panel already has inside it, a 60A breaker to the 5.5kW heat pump, a 50A breaker to a 2.5hp circulation pump, then a few more 20A breakers to the lights and other outlets etc. It does have space for another two pole breaker that could power the new spa heater, but can it handle another 50A load?

So, I’m caught in two minds.
1. Do I get a 60GFCI breaker for the new heater and pop it into the pool sub panel and use the existing wiring feed.
2. Do I follow the heater instructions and install yet another sub panel using 6AWG over a 35 foot span from the main outlet box. The wire is $225 for 100 feet at home depot..

If the mains to pool sub panel wire is 4AWG will the wire support the load of a heat pump, pool pump and spa heater?

Please help.
Hello there and welcome to Just Answer. My name is XXXXX XXXXX I will be assisting you today. I am an engineer with over 30 years of electrical and electronic training, repair and installation experience. I will try and answer your question accurately and precisely so that we can get you on your way.

The answer is no. Your existing arrangement will not support another 45 amps of load (11Kw @ 220V).

A 60A breaker can be loaded up to 80% which is 48A. There is no way you can add 45 A to that existing load and be under 48A.

Sorry :(

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