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Old 06-25-2009, 12:43 PM   #1
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Quick wiring question with HVAC


Quick question. I have a 10 ga. wire in my breaker box feeding a 45 amp breaker for my HVAC unit. I know that it should have an 8 ga wire for that size as a general rule.

However, we also have a breaker outside adjacent to the unit. I am not at the house to know what size breaker is outside at the unit.

This house was built in 2004.

I have been told two different things and don't want to run another wire to the inside box if at all possible.

Any ideas?

Gary

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Old 06-25-2009, 12:48 PM   #2
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Quick wiring question with HVAC


Check the name plate on the outside unit. Look for "minimum circuit ampacity" to tell you what size wire is necessary. Look for "maximum fuse or circuit breaker" to tell you the breaker size. It is very possible you will see a value under 30 for the circuit and 45 for the breaker. That means what you have is OK.

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Old 06-25-2009, 12:56 PM   #3
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Quick wiring question with HVAC


It says the minimum is 40 and the max is 45 on the seal of the outside HVAC unit. Inside the house on the main panel it is a 45 amp breaker which sounds fine but I have a 10 ga wire to the inside breaker.

My question is in relation to the wire. Is it OK to have a 10 ga wire to the inside box knowing that I already have an outside breaker?
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Old 06-25-2009, 01:18 PM   #4
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Quick wiring question with HVAC


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Originally Posted by Gjtrafl View Post
It says the minimum is 40 and the max is 45 on the seal of the outside HVAC unit. Inside the house on the main panel it is a 45 amp breaker which sounds fine but I have a 10 ga wire to the inside breaker.

My question is in relation to the wire. Is it OK to have a 10 ga wire to the inside box knowing that I already have an outside breaker?
You are looking for "Minimum Circuit Ampacity", not minimum breaker size.

Having 10ga wire with a 45A breaker on an HVAC compressor is not uncommon, and if the nameplate numbers agree, it is compliant and is not a concern.
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Old 06-25-2009, 02:03 PM   #5
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Quick wiring question with HVAC


It is possible the outside breaker is not a breaker at all but only a disconnect switch that looks like a breaker. An example would be a Square d QO 200TR a/c disconnect swtch.
Ignore the list price you can get them for 15 bucks most anywhere.

Like this

http://images.google.com/imgres?imgu...%3Den%26sa%3DG
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