| A/C breaker issue I have a 10000 btu ac unit that keeps tripping the breaker in the bedroom after a while. The unit itself uses 1020 watts and draws 9.2 amps. The breaker is 15 amp and the only thing in the bedroom that is on is the a/c the cable box, small lcd tv and 2 alam clocks. My question is there a possibility the breaker is just faulty? I don't really have any electrical experience so I figured I would ask here.
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 John GaltForward, MarchPremium
join:2004-09-30
Happy Camp
kudos:5 | How often does it cycle? |
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| reply to Bruschi
It has been running constantly since I installed it because it hasn't had a chance to get the temp down before it trips the breaker. The unit itself is 6 or so years old and haven't used it in that room before.
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 nunyaWho is John Galt?Premium,MVM
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O Fallon, MO
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While it's *possible* that the breaker is faulty; the most likely scenario is that you are simply overloading the circuit and the breaker is simply doing it's job (keeping your house from burning down).
The only way to tell is to measure the amount of current on the circuit at the breaker panel. My guess is that there is more draw on that circuit than you think.
I had two of these calls yesterday. Both were brand new A/C units. They went and got bigger ones because it's been so hot (the old ones couldn't keep up). The general purpose circuits can't take the load.
Window units should really have dedicated circuits in most cases. I wish they would make it a code requirement in homes w/o central air.
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John GaltForward, MarchPremium
join:2004-09-30
Happy Camp
kudos:5 | reply to Bruschi
Is the panel located in an area that is not air conditioned, the garage for example?
If it is, then the ambient temp might be too high for "continuous use", that is, more than three hours. |
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| said by John Galt:Is the panel located in an area that is not air conditioned, the garage for example?
If it is, then the ambient temp might be too high for "continuous use", that is, more than three hours.
The panel is in the basement where it is actually very comfortable down there.
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said by nunya:While it's *possible* that the breaker is faulty; the most likely scenario is that you are simply overloading the circuit and the breaker is simply doing it's job (keeping your house from burning down).
The only way to tell is to measure the amount of current on the circuit at the breaker panel. My guess is that there is more draw on that circuit than you think.
I had two of these calls yesterday. Both were brand new A/C units. They went and got bigger ones because it's been so hot (the old ones couldn't keep up). The general purpose circuits can't take the load.
Window units should really have dedicated circuits in most cases. I wish they would make it a code requirement in homes w/o central air.
Would one of those killawatts meters help me determine the draw on the circuit?
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nunyaWho is John Galt?Premium,MVM
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| Kind of. It only measures the draw of one item. There are probably many on the circuit. There may be some you don't know about.
An ammeter is the proper tool for the job.
Keep in mind a 15A circuit should not have more than 80% continuous load.
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| So the max continuous watts would be around 1440 for a 15 amp breaker?
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nunyaWho is John Galt?Premium,MVM
join:2000-12-23
O Fallon, MO
kudos:8 | Exactly. |
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| OK thanks:) |
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| reply to Bruschi
Using an extension cord? |
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| said by Rifleman:Using an extension cord?
No. But I think I'm going to have to get a smaller unit, probably in the 8000 btu range. There a a couple units that are only using 700 watts which is 300 lower than the one in there now.
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ViperCertified Home Inspector
join:2012-03-22
Toronto | reply to Bruschi
said by Bruschi:I have a 10000 btu ac unit that keeps tripping the breaker in the bedroom after a while. The unit itself uses 1020 watts and draws 9.2 amps. The breaker is 15 amp and the only thing in the bedroom that is on is the a/c the cable box, small lcd tv and 2 alam clocks. My question is there a possibility the breaker is just faulty? I don't really have any electrical experience so I figured I would ask here.
I hope when you talk about the 15 amp breaker you are talking about the breaker for the circuit in your bedroom because the AC unit breaker needs to be on a 30 amp breaker (10 awg wire) or bigger units are on 60 amp breakers (6 awg wire).
Also, the AC unit needs to be on a separate circuit.
Anyways, there could be several things that might causing this to happen. An over sized unit for the breaker, faulty breaker or an undersized breaker etc.
Ah, also, ideally the AC unit should cycle. It should not run continuously.
Be careful sizing your unit if you decide to get another unit because an under sized unit will not cycle and that might effect the life of the condenser.
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TheMGPremium
join:2007-09-04
Canada
kudos:1 | reply to Bruschi
Clamp-on ammeter is such a nice thing to have for situations like this.
Without knowing the total current flowing through the circuit, there is no way to easily pinpoint the source of the tripping. |
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| reply to Viper
said by Viper:I hope when you talk about the 15 amp breaker you are talking about the breaker for the circuit in your bedroom because the AC unit breaker needs to be on a 30 amp breaker (10 awg wire) or bigger units are on 60 amp breakers (6 awg wire). Lol wut? I've never seen a window unit on a 30A breaker. Also, newer high-efficiency central units draw very little power - my dad just had a system installed where each of the 2 condensers only draw about 9A each; the name plate said to use a 15A Max breaker.
/M |
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ViperCertified Home Inspector
join:2012-03-22
Toronto | said by mackey:said by Viper:I hope when you talk about the 15 amp breaker you are talking about the breaker for the circuit in your bedroom because the AC unit breaker needs to be on a 30 amp breaker (10 awg wire) or bigger units are on 60 amp breakers (6 awg wire). Lol wut? I've never seen a window unit on a 30A breaker. Also, newer high-efficiency central units draw very little power - my dad just had a system installed where each of the 2 condensers only draw about 9A each; the name plate said to use a 15A Max breaker. /M Oh a window unit. Sorry, I missed that part.
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nunyaWho is John Galt?Premium,MVM
join:2000-12-23
O Fallon, MO
kudos:8 | reply to Viper
Your generalizations are incorrect. There are many condenser units in residential that use many sizes or breakers and wires.
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ViperCertified Home Inspector
join:2012-03-22
Toronto | said by nunya:Your generalizations are incorrect. There are many condenser units in residential that use many sizes or breakers and wires.
What exactly are you talking about?
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 whizkid3Premium,MVM
join:2002-02-21
Queens, NY
kudos:9 | reply to nunya
said by Bruschi:So the max continuous watts would be around 1440 for a 15 amp breaker? Not exactly (and nunya knows this).
The max continuous volt-amps for a 15 amp breaker is 1440 volt-amps (VA). The continuous wattage for the breaker depends on the power-factor of the load. Since generally, few know what the power factor of their loads are; this makes it very difficult to add up the total wattage to determine if your breaker is going to be overloaded. This especially for people without much electrical experience. Its often easier to simply use 'watts' instead of volt-amps; but when the results are within - plus or minus - a hair of tripping the breaker, its better to use accurate math.
Its much more easier to understand Amps. The max continuous amps for a 15A breaker is: 15A * 80% = 12A. After the 9.2 amps of your air-conditioner, you have 2.8 amps left to spare for continuous loads. If you were to subtract the 1020W of your AC unit from 1440W, you would get 420W. And it would be wrong. You might think you have 3.5A to spare. You don't. The advantage you have here, is that the from the ratings you have on your AC unit, you can calculate its rated volt-amps (VA) and even rated power factor (p.f.):
9.2A x 120V = 1104 VA
1020W / 1104VA = 0.92 p.f. or 92%
On the other hand, nunya's assessment of the reason your breaker is tripping is spot on. You have an overloaded circuit. Very often homeowners believe they know exactly what is on the breaker; but forget or don't realize there are other loads on it. Its wise to shed some loads from this circuit to the point at which the breaker does not trip (or even provide a dedicated circuit for your air-conditioner). Its even more important in this heat, as your wiring at some points is likely exposed to outdoor temperatures. Their capacity is reduced with increased ambient temperatures.
(FYI - in NYC, homes without central AC require dedicated air-conditioner receptacles & circuits in all bedrooms, the living room & dining room).
said by mackey:Lol wut? I've never seen a window unit on a 30A breaker. Then you haven't been around. I have a window unit that has requires a 30A circuit & receptacle. And its 240V.... Yes, its a window unit. That being said is probably one of the largest ever made. And it is older and less efficient. 40k BTU per hour. Yes. Its a window unit! (My problem is it fits in only two windows in the house.) |
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