air conditioner circuit protection


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Old 03-02-14, 09:36 AM
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air conditioner circuit protection

My outside unit on the nameplate says
min circ. ampacity 15.8
max fuse or circuit breaker HACR type 25
Compressor 11.6 RLA 59.0 LRA

This was a new installation this summer. They put it on the same 30A breaker/#10 the old one was....

That's completely wrong right? Should I be making a stink with the installer? What is the proper electrical requirments for my A/C?
 
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Old 03-02-14, 09:46 AM
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No... that's not completely wrong. The wire size is correct. They are allowed to go up to the next breaker size if the needed one is not available. Technically the breaker size should be 25A but that would be a special order and may not be available at all.

Do you know what brand panel you have and maybe the breaker style number or even a picture.
http://www.doityourself.com/forum/el...-pictures.html
 
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Old 03-02-14, 09:47 AM
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There could also be 25 amp fuses in the outside disconnect. 25 amp breakers are not that common in the big box stores, but are easily available at an electrical supply. 25 amp fuses are fairly available everywhere.
 
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Old 03-02-14, 11:24 AM
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30/10G is pretty standard, maybe you should call the installer and see if they have a 25A breaker for your installation since its new?
 
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Old 03-02-14, 02:11 PM
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Before I called the installer i'd check for 25A fuses in the disconnect like Tolyn suggested.
 
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Old 03-02-14, 05:06 PM
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If its a non-fused disconnect, does the 30A breaker have to go?

Stupid question, but if the ac is rated for 15A, why not a 20A breaker and #12?
 
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Old 03-02-14, 05:11 PM
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You cannot load that breaker past 80%, so on a 20A circuit you are allowed 16A.
You must take the AC draw at 125%, so it would be considered as drawing 19.75A.
So cannot use a 20A breaker.
 
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Old 03-02-14, 06:20 PM
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Stupid question, but if the ac is rated for 15A, why not a 20A breaker and #12?
The manufacturer says the MCA is 15.8, that's too much for a 15 amp breaker. The manufacturer also says MAXIMUM 25 amp breaker so a 20 amp breaker might work, but you cannot exceed a 25 amp breaker. The #12 wire is correct.
 
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Old 03-02-14, 06:26 PM
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The larger breaker allows for the high startup current from the compressor to not trip the breaker.
 
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Old 03-02-14, 06:31 PM
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Yep ....................................
 
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Old 03-03-14, 02:47 AM
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So can I continue using this with a 30A breaker? One posts says they are allowed to go one up another post says I cannot exceed 25?


Thank you.
 
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Old 03-03-14, 08:46 AM
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You can only use a 30 amp breaker if you have 25 amp fuses in the disconnect. The unit cannot be protected above 25 amps.

The manufacturer also says MAXIMUM 25 amp breaker
 
  #13  
Old 03-03-14, 03:06 PM
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I checked the disconnect and its 60A non-fused.

So essentially they changed nothing nor informed that something needed to be changed. Should fixing this be on the installers dime?

So I either need a 25A breaker or a 25A fused disconnect?

FWIW I have a square d homeline panel... do I have go to a hvac supplier to get the right breaker? Should I be using #12 or #10 wire?
 
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Old 03-03-14, 03:18 PM
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The installation should be correct and code compliant. The breaker is the easiest fix. I think you need to make a phone call.
 
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Old 03-03-14, 04:10 PM
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I don't think I will have any luck with a double pole 25A homeline breaker locally....

The disconnect is OK correct? Rated 60A.... I assume that means you can use it up to that amperage.....

10 or 12? Thinking 10 to eliminate voltage drop on the LRA?
 
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Old 03-03-14, 06:04 PM
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#10 wire is fine. Maximum breaker is 25 per manufactures nameplate. They should install a 25 amp breaker.

The code states "if there is not an overcurrent device available, you can go to the next larger size". That doesn't mean you can't find one in the truck or store, that means manufactures do not make one that size. The code states that a 25 amp breaker is a standard size overcurrent device. They need to provide the proper breaker.
 
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Old 03-03-14, 06:14 PM
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I wouldn't call it an emergency, but it needs to be replaced with the proper breaker before A-C season. They aren't that hard to find. A supply house that stocks Square D probably has them in stock.

Shop Square D Homeline 25-Amp Double-Pole Circuit Breaker at Lowes.com

Square D by Schneider Electric Homeline 25 Amp Two-Pole Circuit Breaker-HOM225CP at The Home Depot
 
 

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