What size wire and breaker is standard for a rough in pull on a 4 ton unit? 8/2?50-60 amp? I haven't decided on which unit I'll be purchasing yet so I can't get the specs off the unit. What do most 4 ton units require?
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50 amp max on most 4 ton units. -
50 amp #6 wireComment
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You can run larger wire and put a smaller breaker I believe. I think even on my 5 ton unit it is a 50 amp.Comment
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Yes you can over size the wire, but just make sure it fits under the breaker. The trimming of wire hairs you are NOT supposed to do. Does it happen? Yup.Comment
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I talked to the guy who gave me a quote on the 4 ton two stage heat pump and he said run 8/2 to the outside unit with a 50 amp breaker and run two 8/2 with 60 amp breakers to the inside unit. ? Does this sound right? I thought for 60 amp breakers it would need to be 6 gauge. I didn't questioned him too much on it because he installs the heat pumps for a living.Comment
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The higher amperage is to cover the auxilliary heating coil in your air receiver for those extra cold days when the heat pump can't keep up... Not sure about the wire size...
Size can also be critical depending on how long the run is...Comment
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I would go with 6Comment
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15kw heat ?Comment
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A 4 ton unit normally states min and max on the side of the unit. A rheem RP1448 I believe is 29 min and max 50. Rule of thumb always max. But you can add the compressor amp and cond fan motor and get total so say 22+2 =24 then x1.25 fr wire size so that equals to 30 so number 10 wire. Now problem here is code only allows 30 amp breaker on 10 wire. So next calculation is breaker size. So 24 x1.5 this is 36 Amps. Which means a 40 amp breaker. Also means now you need to use number 8 wire due to 10 cannot be installed on a breaker bigger then 30. Haha lots of info just to say out side unit you need #8 with a 40 amp breaker.
As far as inside unit. That depends on how much electric heat. Do not let them sale you just 10kw. Make sure you get what the house requires if your electric heat only. This is Incase the heat pump goes down.
So if you get a 18kw heater that’s 75 amps. Plus around 8 for motor. Most people run #4 and put on a 100 amp breaker. By code if you can find a 90 amp breaker that is what it needs but if a 90 is not an option 100 by code is correct.
One stipulation. By code anything under 100 amps is supposed to be used on a 60° chart. This means nothing to you, but to an electrician yes. This would mean #3 to the unit.
If two sets of wires are ran it’s a common to run to sets of # 6 to heater with 60 amp breaker
But who ever installs should take care of all of this.Comment
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The old wire was 6/2 to the outside and 4/3 to the inside unit. Inside unit had a 100 amp breaker. But all of this was ran to an outside panel that is no longer there. A new panel was installed inside the house. I think the old 4/3 is still good wire and is long enough to make a run from the panel to the inside unit. I would need to get a 100 amp breaker for the new panel though. Would reusing the 4/3 and buying a 100 amp breaker make a difference vs. running two new runs of 6 or 8? It would save me a couple of breaker spaces to run the old 4/3 wire.Comment
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Most 4 tons can run on 40. For your electric heat, look at what the heat kit specifies. 20kw is a lot for 4 ton.Comment
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Run that existing 4ga wire to the main panel with 100a breaker. Run it to sub panel next to indoor unit. 15k is plenty. One 60 and one 30 with 6 and 10 ga wire to heat kit out of sub-panel.
Outside, plan on 50a circuit. 8 is probably ok if it’s a short run, but I would run 6 ga to be safe. Still easy to stab into a 50a breaker.
Not sure if this decision has been made yet, but go with a heat pump! Way cheaper to operate in heating mode than resistive heat!Comment
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