Circuit Breaker for HVAC Question

txmatJanuary 14, 2014

This AM the circuit breaker on the house panel for the HVAC air handler and thermostats tripped. I reset and it tripped again in about an hour. A technician came out and advised me that the CB on the house panel was 50 amps and on the air handler there was a 60 amp circuit breaker which was also wired to a 30 amp circuit breaker. The 60 amp protects the blower and other components and the 30 amp the heat strips (This is a heat pump). The technician suggested I needed to change the circuit breaker on the house panel because I was actually pulling 90 amps. Now to summarize as I understand it electricity enters the house through the 50 amp circuit breaker and then travels through the 60 amp CB and then for the heat strips travels through the 30 amp CB. This setup has been working this way since 2009, so I am wondering first, is he correct; second, do I need to change the house panel circuit breaker; third, if yes than what amperage should it be? I will appreciate any help you can give me in understanding this.

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The technician may be correct-- or not. I think you need a good electrician. Your post does not indicate that you are ready to personally adequately address this situation.

    Bookmark   January 14, 2014 at 8:10PM
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If you paid him,insist he give your money back then get somone who knows what they are doing.

    Bookmark   January 14, 2014 at 10:34PM
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Well, you cannot pull more than 50A through that panel breaker regardless of what other breakers you have installed.

Really a 50A panel? That is a subpanel, right? Not for the entire house?

If you are suddenly popping the breaker that runs your HVAC, your compressor might be going bad. If it eventually shorts out, you'll pop your breaker. Don't simply add a larger breaker and with the 50A panel breaker it won't help anyway. The breaker size and wire size are computed using information on the HVAC's label and from various tables in the NEC handbook. If you want it sized correctly, you'll want a qualified licensed electrician.

    Bookmark   January 14, 2014 at 11:02PM
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Thanks. Jreagan, the panel has several breakers. There is a 50 amp for the outside part of the heat pump plus the one I am asking about which is 50 amps for the inside portion of the system. These are just the two breakers in the panel for the HVAC. They are not for the whole house. There are several other breakers in the main panel and three sub panels. I am asking about just the one breaker that tripped a couple of times today. I think I understand that even though there is a 60 plus a 30 amp breaker on the air handler there can be no more than 50 amps running through them because that is the size of the breaker at the panel or "upstream." Can I assume that since the system has run without problems for 4 years it probably does not need more than 50 amps.

    Bookmark   January 14, 2014 at 11:43PM
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Your assumption is correct.
You need somone compitent to, (A.) Test amp draw of unit to see if it is drawing more than 50 amps or if draw is only 40 amps tripping a worn out 50 amp breaker. (B.) If unit is drawing more than 50 amps,find what is wrong and fix it.(C) If draw is less than 50 tripping worn out breaker,replace breaker.
Everone has told you to have it looked at by a pro. It is not wise geathering information to pass on when he arrives.

    Bookmark   January 15, 2014 at 4:39AM
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Thanks. Klem1, I do not understand why it is not wise to gather information to pass on when a pro arrives? If you mean it is not wise to tell him how to do his job, I agree. But, how does it hurt to have an understanding so that I can understand what the pro is telling me and evaluate it? I mean the AC guy is a "pro", but when he suggested I needed to replace the 50 amp house panel breaker with a 60 amp I was skeptical and so I came here to one of my favorite sites. If I had blindly followed his advice, maybe nothing bad would have happened, but it may have been an unnecessary expense. Do you think I am wrong to question what I am told? Everyone's suggestion to get an electrician to determine the load and size the breaker and wiring accordingly makes sense to me. I just don't understand what your meant by that sentence.

    Bookmark   January 15, 2014 at 9:32AM
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