20 amp service and A/C use

[HawkinGal]

The little (20 sites) campground at my Michigan sporting club only has 20 amp service. Members say their ac's generally work fine, but you don't use the microwave at the same time, etc.

I'm shopping for my first camper (will probably be an '80's Airstream as that vintage is in my price range) and have heard contradictory reports re: ac's and 20 amp service.

Just got off the phone with the seller of an '85 Sovereign 29' who says his original Coleman ac doesn't make the trailer cold on 20 amp, ice-cold on 30 amp.

Is his experience typical? Thoughts? I don't care to get a genny.

[idroba]

Most AC units will operate fine on a 20 amp service, but you don't want to have anything else on at the same time, like the electric element in the water heater if you have one. No microwave. Best to switch the refrigerator to propane also, when you are on limited electric service and want the AC on.

You also want to have good quality adaptors to go from the 30 amp trailer plug to the 20 amp outlet so you have no/minimal voltage drop at the connection.

The seller of the Sovereign who says the Coleman does not make it cold on a 20 amp service and "ice cold" on a 30 amp service is full of BS, unless he has a very poor conversion connection (mentioned above) or a very poor 20 amp outlet with low voltage to begin with. A significant voltage drop will make an AC produce somewhat less cooling and ultimately damage the unit.

If others at the campground say their AC units work fine with the 20 amp service, yours should also work well. The AC units on Airstreams are the same as the ones on all other RV's, not special to Airstream.

[Zil]

Every 20 amp service is not the same. Some, because of long distance runs of the wiring, have reduced voltage at the appliance. Low voltage will eventually kill the motor.

[airdreamers]

I have no problem running my Coleman A/C, 13,500 on 20 AMP. Cool is cool, also depends on weather conditions, outside temp etc, all thing have to be considered. The breaker for the A/C is a 20 AMP, I assume original. I am not in a habit of running all of the appliances at once, what's the point of it. Good Luck on a purchase, you will love it!

[Jammer]

Originally Posted by Zil

Every 20 amp service is not the same. Some, because of long distance runs of the wiring, have reduced voltage at the appliance. Low voltage will eventually kill the motor.

True.

What matters most is the voltage at the trailer. As long as it stays above 110 even with the A/C running, you're fine. Badly wired campgrounds can deliver insufficient voltage to 30a and 20a connections alike.

It's about wire size and distance. At one location where I stayed for 8 weeks, the shared power pole was 80' away. I ran 6 gauge cord, and it worked out fine.

[cwf]

You MUST check your voltage "under load". That means, turn on the AC then check voltage at one of your outlets. If not at least 108VAC, you will cause shortened life of AC.

[HawkinGal]

Cannot even begin to tell you all how happy I am for this info. I have relayed it to the seller, who checked his owner's manual which said ac only drew 14.5 amps, and we are working out a way to test out his rig using other outlet, adapter, etc.

Saturday is our club party. I will bring a voltage meter and check my two neighbors voltage with their ac's running.

[Getaways]

Wait, what, you need A/C in Michigan?

[HawkinGal]

Not this year! We found a use for this "Polar Vortex!"

But in a normal summer here in SE Michigan, we'll get a bunch of days in the 90's. Even so, my campsite is shady, so I expect I'll very rarely use the ac. But when you need it...

[TouringDan]

Sounds like you are in good shape with the Airstream you are planning on buying and your hunt club. I might suggest that you purchase a "watt meter". These are only about $30 and tell you the line voltage and the power being used by whatever is plugged into it.

Have fun, Dan

[1965 mustang]

Will ac run with a honda eu2000 ?

[Al and Missy]

My 11000 BTU unit will run on my 2000i, but my friend's 13,500 BTU won't run on his.

I'm not convinced that the 2000i is enough to not damage the AC long term. I'm working on a test and will post the results when I finish.

Al

[mefly2]

Our AC in the FC 20 ran fine with an EU2000...

[1965 mustang]

I was curious if that would work. I'm plugged into a 20amp outlet in the garage and my ac works. I converted to LED lights so that takes a lot of load off. Probably wouldn't be able to use the microwave at the same time but we rarely use it anyway. I have been looking at generators and didn't really want to step up to the eu3000 because of its size.

[Wayward]

Originally Posted by HawkinGal

The little (20 sites) campground at my Michigan sporting club only has 20 amp service.
Just got off the phone with the seller of an '85 Sovereign 29' who says his original Coleman ac doesn't make the trailer cold on 20 amp, ice-cold on 30 amp.

What the seller told you does not reflect Ohms Law. I would be very skeptical.

Appliances like a rooftop AC draw a fixed amount of current in amps. If the campground outlet supplies that amount of amps (or more) it will work fine. If the campground outlet supplies less amps than the A/C needs, the campsite breaker flips off.

It can easily be calculated. Just find the wattage specs for your model A/C.

A Mach 3 13500btu A/C for example specifies wattage as 1595/1924. Watts divided by voltage gives current. So....

1594watts/120volts = 13amps on low
1924watts/120volts = 16amps on high

The 20amp service at your campground would run the Mach 3 and leave a few amps for other things.

If that Mach3 tripped a 20amp breaker at 120v, something is wrong with it.

[lsbrodsky]

I hesitate to jump in but motors draw a fixed power during operation so if the voltage is low, the amperage draw will increase. Your division is correct but all induction motors will draw much more power, and current, when they start. So a compressor will draw up to 3 times its running current when it starts. It is a momentary draw and if the breaker is rated high enough, it will not trip, risky with a 20 amp breaker circuit, though. In addition, if the circuit cannot provide the voltage needed repeated starts at higher amperage will result in early failure of the compressor motor. I just do not see why people risk their equipment by trying to run AC on a 20 amp circuit.
Larry

[1965 mustang]

It doesn't seem to struggle and the breaker doesn't trip, can damage still be done? If you put a thirty amp breaker in place of a twenty amp it really doesn't change anything but the amps in witch the breaker trips. The problem would then be the wire size. Thirty amp should have #10 twenty should have # 12. The wire size could restrict the amps/volts. Correct ?

[Wayward]

Originally Posted by lsbrodsky

I just do not see why people risk their equipment by trying to run AC on a 20 amp circuit.
Larry

Running a 15amp appliance from a 20amp campground circuit is not going to harm it anymore than running it on low voltage from a 30amp campground circuit.

Yes, of course, campground voltage lower than the A/C is rated for will cause a corresponding current increase. The individual circuit breaker in the RV beaker box is there to protect the A/C should current get too high.

If the campground's voltage gets so low that a 15amp rated A/C trips a 20amp campground breaker, moving to a 30amp site will not help. Its voltage will be low too, so then the 20amp breaker inside the RV will trip.

[Wayward]

Originally Posted by 1965 mustang

It doesn't seem to struggle and the breaker doesn't trip, can damage still be done?

No damage will be done from running an typical 15amp RV A/C from a circuit protected by a 20amp breaker.

Originally Posted by 1965 mustang

If you put a thirty amp breaker in place of a twenty amp it really doesn't change anything but the amps in witch the breaker trips.

Basically you are correct but you really would not want to do that unless you first verified that the circuit wire was large enough to handle the higher current the 30amp breaker would permit to flow. If not the wire will heat up and could melt/burn. It is very likely that the wire size of a circuit with a 20amp breaker was sized to handle 20amps max.

You can however put a 20amp breaker on the larger wire sized for a 30amp circuit breaker.

Originally Posted by 1965 mustang

Thirty amp should have #10 twenty should have # 12.

Usually.

Originally Posted by 1965 mustang

The wire size could restrict the amps/volts. Correct ?

Wire has resistance so it always restricts current and lowers voltage. Wires are sized large enough that the resistance is negligible over the short distances used in buildings and RVs. If you pull more current than a wire was sized for, that resistance causes excessive heat. In such a case, the breaker is to be matched to the wire so it trips before the wire gets hot.

[kscherzi]

Use a voltmeter. If you read 110 volts inside your AS or higher with AC on then you should be okay. If lower then turn the AC off and save it from burning out.