Air conditioning


Old 06-27-01, 09:49 AM
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Hi, I have a 12000 btu air conditioner that is tripping the breaker. This is an old house that has outlets that are not grounded also. I know I need to replace these outlets but I really wanted to know if I need to have work done to the breaker box to accomodate this load. The air conditioner doesnt require 220 service but I need to do something to correct this issue. What do I need to do?
p.s. The breaker switch that keeps tripping has the #15 on it.
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Old 06-27-01, 10:31 AM
Join Date: Sep 2000
Location: Fayetteville, NY, USA
Posts: 1,052
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First, a word of caution: The NEC forbids increasing the breaker rating unless all the wiring on that circuit is of a specified gauge. Your breaker is rated 15 amps. This is rated for #14 wire but the wire is permitted to be larger gauge. In order to change it to a 20 amp breaker all the wiring on that circuit must be #12 AWG. Many times a homeowner will increase the fuse or breaker size because the regular tripping of that circuit is a nuisance. This allows more amps to flow through that circuit's wiring than the wire is rated for and this causes heat, which is the cause of many, many house fires.

Now, there must be a nameplate on your AC unit. Unless it is an old unit the nameplate will list the maximum breaker size needed.

As far as needing work on your breaker box I can't tell. First I would need to know the size of your main breaker and what major appliances you have that are electric. There are calculations in the NEC to determine the correct service size for your overall loads which take into account AC, receptacles, lighting, major appliances, etc., and includes your total square footage as well. An electrician can do this for you. And often times we can pretty much ballpark it for you in this forum. If, for example, you have a medium size home with a 100 amp service and have mostly gas appliances (heat, hot water, range, dryer) then adding an AC unit that is rated for a 20 amp circuit should not be a problem, in very general terms.

If you mean simply changing a breaker this is an inexpensive proposition, but please heed my first paragraph. They typically cost about $4. Even if you hire an electrician this job will not set you back much. S/he will first verify your wire gauge, and if the nameplate indicates a 20 amp breaker and the wire size is correct you're in good shape to have this done. That's the best case scenario.

Lastly, if you determine you need a 20 amp breaker but your wire is only #14, and you determine that your breaker box rating is sufficient to add this load, and you have additional unused spaces available, (There are usually at least a couple blank spaces. These blanks can usually be snapped out and additional breakers installed for new circuits.) then you could run a brand new 20 amp dedicated circuit to the AC. Or have a pro do it. This is not an expensive job usually and for most houses in most areas of the country I'd be surprised if this cost $200.

I hope that helps.

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