Mis-wired furnace/AC?


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Old 03-18-14, 10:55 AM
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Mis-wired furnace/AC?

While doing some rewiring work, I noticed something I thought was odd. I have a two-pole 30 A breaker that was labeled ‘furnace' (high-efficiency gas furnace), and the single-pole 20A directly above it I never figured out what it was for. When I had the panel open, I followed the wires. The hot on the 30A runs outside to the A/C, but the neutral on the 30A runs to the furnace. The hot for the furnace runs to the 20A. Is this normal, or should I switch it?
 
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Old 03-18-14, 11:06 AM
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A/C units don't have neutrals. They have two hots and a ground. It is acceptable practice to use 10/2 cable, and use the white wire as the second hot (it is supposed to be marked black though).

I don't know what you mean by the 'neutral' going to the furnace though. The furnace runs off the 20A breaker. Nothing on that 30A breaker should be going to the furnace. You must be mistaken as to what takes what route.. Because if the A/C unit didn't have both hots, it wouldn't work.
 
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Old 03-18-14, 11:09 AM
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That doesn't sound correct. Don't change anything yet. I can't visualize what you are describing.

Is the unit outside a 240 vac unit ? If it is and it's been working ok then maybe you didn't follow the wiring correctly.
 
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Old 03-18-14, 01:01 PM
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I did not follow correctly. It looks like the 30a goes outside I the ac an the 20 is for the furnace.
 
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Old 03-18-14, 01:06 PM
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That would make sense..... the two pole 30A breaker is just for the compressor unit.
The furnace could be connected to a 15A or 20A circuit..... so that's good too.
 
 

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