central air conditioner question

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  #1  
Old 07-15-12, 11:17 AM
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central air conditioner question

I was recently looking at my mothers main panel and I noticed that the breaker for the central air, is a two pole 15 amp. Doesn't this seem small? It has been on this breaker since the house was built in 1987, and there have been no problems with it, it just seems odd. I went outside, and looked at the tag, and this is what it reads.

MIN CKT AMPACITY 18.5
MAX TIME DELAY FUSE 30 AMPS
MAX HACR TYPE CKT BREAKER 30 AMPS
MAX CIRCUIT BREAKER (CSA) 30 AMPS
COMPRESSOR 208/230 V 13.7 RLA 65.0 LRA
FAN 208/230 V 1.3 FLA 3.5 LRA

Can someone decipher this tag for me? I understand some of it, but is it telling me that the compressor can draw as much as 65 amps? I don't know what RLA, LRA and FLA mean, other than that the "A" is amps. Thanks.
 

Last edited by the_tow_guy; 07-25-12 at 05:34 AM. Reason: Typo fix
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  #2  
Old 07-15-12, 12:23 PM
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Has the breaker been tripping? If so, under what conditions, if that can be determined?

The breaker is to protect the wiring.

What size wires are going from the breaker to the A/C unit?

I guess it's possible the breaker is "stuck" in the closed position and then you'd have no protection for the wiring and that could be a safety issue if the device drew more current than the wires could handle.
 
  #3  
Old 07-15-12, 12:42 PM
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The breaker has never tripped. I just was looking, and noticed the size of the breaker. It is wired with #10 AWG.
 
  #4  
Old 07-15-12, 01:09 PM
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If it ain't broke don't fix it... but do exercise it. Turn the breaker on and off a couple of times to make sure it moves freely and check it really cuts off the power. What brand is the panel?

Just to be sure we are on the right wavelength it does say 15 not 30 on each breaker handle doesn't it.
 
  #5  
Old 07-15-12, 01:11 PM
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I'm not an electrician and you should always understand the electrical code or hire one.

Typically, 30A breaker is used with a 10ga wire circuit. But there are situations that would allow or dictate other materials.

So, unless the breaker is stuck closed, you could say that your device is drawing less than the breaker is protecting for.

Or, in other words, you are over-protected by having a 15A breaker protecting the 10ga wire.

Maybe someone can jump in with a safe homeowner technique to check that a breaker is able to trip... I have never used the "dead short" method of checking a 30A breaker.

If testing is not possible, then you could just replace the breaker with a brand new one - that might provide some comfort.

Or, if you have a current tester, you could measure the current that the device is drawing. If it reads under the 15A rating for the breaker then you have a better comfort level that things are OK.
 
  #6  
Old 07-15-12, 01:38 PM
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Technically it's a code violation. The manufacturer states minimum circuit of 18.5 amps which requires a 20 amp breaker (up to a max of 30). Currently, it's on a 15 amp circuit.
 
  #7  
Old 07-15-12, 02:25 PM
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Ray, It is a Cutler Hammer CH30JJM200. It is a two Pole breaker with 15 on each breaker handle. The breaker works fine. Shutting it off, shuts the unit off.
 
  #8  
Old 07-15-12, 05:24 PM
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It is a two Pole breaker with 15 on each breaker handle. The breaker works fine. Shutting it off, shuts the unit off.
It sounds like the breaker is still functional, and everything has been working since 1987. I'd close 'er up. Go back and check it again every once in a great while.
 
  #9  
Old 07-15-12, 06:50 PM
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From the data you posted, it appears that with a full load on both compressor and condenser fan you would be drawing 17.2 amps. If the unit is not fully loaded, the amperage will be something less that FLA and the condenser fan is probably never fully loaded. I think I'd be more comfortable if it was on at least a 20 amp breaker, but I wouldn't worry about it unless the 15 amp breaker starts tripping. I will assume this is an older 2 or 2 1/2 ton a-c unit in a smaller home.
 
  #10  
Old 07-16-12, 07:48 PM
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Really hot weather or a dirty condenser could make that ac pull a full load, and trip the breaker, leaving you without ac on the hottest days.
 
  #11  
Old 07-25-12, 12:02 AM
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To help you decipher the tag:

RLA is the running load amps, also referred to as the full load amps. This is the current the motor will draw when running at its rated capacity. Your compressor will draw 13.7 A and your fan will draw 1.3 A at rated capacity for a total of 15 A.
The LRA is the locked rotor amps, basically the current the motor will draw when it starts or something causes the compressor or fan to jam. The motor normally only draws this current briefly when the motor is switched on. You don't have to worry about the LRA in most cases (just don't use a fast acting fuse on this circuit).

So your 15A breaker is right at the limit of your normally expected draw. As others have said, this won't endanger the 10 ga wiring but the circuit isn't technically complying with the nameplate requirement of 18.5 amps capacity.
 
  #12  
Old 07-25-12, 06:36 PM
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your fan will draw 1.3 A at rated capacity
Ooops! I added LRA instead of FLA on the condenser fan.
 
  #13  
Old 07-25-12, 07:25 PM
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Thanks guys for breaking this all down.
 
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