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fireman0175 08-03-2009 12:58 AM

heat pump install wiring question
Hi All,

I am required to supply pig tails for my new heat pump and air handler/heat strips. I have done all the wiring in my home, but this one is perplexing.

The length of the wire run from the box is about 70' to the air handler with the 15kw heat strips. The heat pump is about 70' also.

The heat pump calls for a minimum branch circuit ampacity of 28 amps, but minimum circuit breaker protection rating of 40 and a max brkr of 45 amps.

The air handler/heat strips requires 2 circuits with one providing power to the air handler itself. It lists a heater amps per circuit of 40/24. So, it calls for minimum circuit ampacity of 55/30 with a maximum overload protection of 60/30.

So, I am trying to figure out what the minimum gage wire for each of the three circuits. It is all inside my residence. Also, what size breakers should I install?

Thanks alot for you knowledge.

InPhase277 08-03-2009 01:12 AM

If you are using nonmetallic type cable, i.e. "romex", then you have all the info you need. For the heat pump, the min. circuit ampacity is 28 A, so you need a wire capable of carrying at least that. 10-2 is sufficient. A max circuit size of 45 A means you can use a breaker large as 45 A, but no less than 40 A. Since this is a residence, I'd probably use 8-2 with a 40 A breaker.

On the air handler, it says you need two circuits, one capable of carrying at least 55 A, and another of at least 30 A. So, 6-2 and 10-2 respectively. Breaker sizes are 60 A (because there are no 55 A breakers available) and 30 A. Don't for get to provide a disconnect for all your circuits local to the equipment.

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