Running AC on 15 Amp Circut

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hoss10

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Mar 13, 2016
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Going to be hot this weekend and the Grandkids like to sleep in the trailer.
Can I run the AC on a 15 Amp circuit, or will I damage the AC unit.  There will be no other uses on the line.  It's in a shop, I have lots of 20 and 30 amp curcuits but they are 220 V!

Thanks for the help.
 
It may or may not run, but it won't damage it as long as you use a adequate extension cord. Too small a wire gauge will cause a voltage drop. Try to use just the RV shore cord and adapter, but if you need an extension, use at least a 12 gauge cord. 10 gauge if over 20 ft.

Make sure everything else in the RV that uses 120v power is turned off. 15A is barely enough for the a/c alone.  It actually needs more than 15A to start the compressor, so don't be surprised if the breaker in the house trips.  Also, the outlet circuit you plug too must not have any other active loads - the RV a/c is going to demand every milliamp of available power.
 
Thanks Gary It will be plugged directly in with no extension.  I have no problems with tripping my breaker, I thought I had read something sometime about potential damage to AC unit.  I will give it a try.
 
One thing you can do to reduce amp demand at start up of the compressor is to have the fan on the unit already running. I am sure the AC takes 120 volts only.
 
If the a/c has a wall thermostat, it will use a small amount of 12 volt power to run it and the interface.
 
hoss10 said:
Thanks Gary It will be plugged directly in with no extension.  I have no problems with tripping my breaker, I thought I had read something sometime about potential damage to AC unit.  I will give it a try.
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Yes there is a risk of potential damage to the A/C unit if the voltage is to low.  Generally this happens because of a too long a wire run with too small wire size.  It is best to have the voltage at or above 110V.  Getting down to near 104V or lower is most stressful.
I carry something like this voltage display: https://www.amazon.com/dp/B01MZ208H8/ref=sspa_dk_hqp_detail_aax_0?psc=1 and just leave it plugged into an outlet so I can see what the voltage is when the A/C is on or when the microwave is on. 
 
We run our 1350 watt Coleman air conditioner in our trailer off a 15 amp circuit when the trailer is parked beside the house. But, as Gary mentions, don't run any other loads, and if you do require an extension cord, make sure it is a brutally thick one. :)
 
I would measure the voltage inside the RV. below 110 is not good.

Other than that if you overload the 15 amp circuit. it will simply shut off. No damage.
 
I have an EMS to protect my power in my trailer ad with nothing else on my 13.5K AC takes right at 16 amps to run when it 95* out. Our 15K takes the same to run. My shop RV receptacle is 50 amp running a trailer set up for 50 amp

If you are running over 12 to 13 amps on a 15 amp outlet steady run that is about all you can expect from  a 15 amp ckt. A breaker is designed to run at 80% of capacity for any length of time and a surge of 15 amp.

To low voltage and the AC motor runs slower which causes heat. This can over time can harm the motor if not right away. It may not fail now but the chances are greater  that it well fail sooner than it should. Another thing to check is the heat on your 15 amp adapter, if it is getting hot not a good thing.

Here is a link to low voltage and higher currents.

http://www.ecmweb.com/design/highs-and-lows-motor-voltage


Here is a link for how many watts to have capacity for surge.

https://sciencing.com/capacity-15-amp-circuit-12175189.html

Scroll down to "Maximum Load vs. Safe Load" for an explanation on the 80%.


This is IMO and yours may differ.
 
Right. The breaker may well trip after 30 minutes or so at 13A-14A and that is within normal operating specs for a 15A breaker.

Low voltage is the possible harm to the a/c and that depends on the size & quality of the wiring, not the circuit breaker capacity.
 
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