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Old 12-16-2008, 03:12 PM   #1
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The 20 amp shore power debate

I have a debated question for all you electrical people out there....
I have been using a 20amp GFI dedicated circut from my garage to power my A.S. will parked in the driveway...I have run all systems endivigualy and some at the same time...mainly AC and 12v lights also fridge at the same time oh and the tv.
Someone told this was bad for my AC and Fridge...
So I called A.S. tech suport and the long and short was that it was ok for the systems
Also called Fridge and AC manufacture and also got the a green light from them
All in all they both said that the breaker in the pannel box of the garage would trip if to much amps was drawn at the same time
Also the amps for the fridge and the AC combined didnt equal 20 amps
My debate partner said that everyone was wrong and that I would burn up my AC and Fridge if I continued to do so...
Any Thoughts
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Old 12-16-2008, 03:29 PM   #2
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I have run on 15 amp, all of us have...got to be carefull though, roof air is out; 30 amp is the choice. We need spell check on this forum.
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Old 12-16-2008, 03:38 PM   #3
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We need spell check on this forum.
If you use Firefox as your browser, it will spell check for you on any forum.
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Old 12-16-2008, 03:54 PM   #4
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You can run nearly any of the appliances off the 20a line....except for the A/C unit, and for sure not the A/C unit if you are running other power hungry items off shore power like fridge, microwave, AV systems, etc.

The best practice is to pull a 30a line to your garage. That way, you can run whatever you want and if wired correctly, all at the same time.

If you want to see how your systems react, try running them off a generator. Put a 2000 watt job on it and run the A/C and fridge. If it still runs and doesn't kill it (and or you don't hear the compressor on the A/C unit straining-- which will destroy it in the long run), I'd say yer ok, but for the 13.5k BTU units and larger, I would always suggest a dedicated 30amp line.

Keep in mind that although your circuit may be 20amps, in all likelyhood the outlet is a 15amp outlet, further compounding the issue.
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Old 12-16-2008, 04:11 PM   #5
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in all likelyhood the outlet is a 15amp outlet, further compounding the issue.
The point I was making.
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Old 12-16-2008, 04:44 PM   #6
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Keep in mind that although your circuit may be 20amps, in all likelyhood the outlet is a 15amp outlet, further compounding the issue.
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The point I was making.

why?

that wouldn't be "code", then, would it?

The compressor strain, and subsequent damage, comes from a low voltage situation...which is what happens if you use a long and/or underrated extension cord; not a "less than 30amp" circuit. As long as there is adequate voltage at the a/c unit, I don't see why there'd be any problem. In my trailer, the a/c unit is on a 20amp breaker. As long as the total amp draw of all the running appliances in the trailer doesn't exceed that, where's the problem?
of course, it will exceed 20 amps, if you try to run the a/c, and the microwave, and an electric space heater, and the furnace, and the fridge, and a fantastic fan, all at the same time. Oh, and a toaster. So don't do that.
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Old 12-16-2008, 04:51 PM   #7
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Question Spelleng problum...

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We need spell check on this forum.
Why?... Nothing rong with the one we got.
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Old 12-16-2008, 05:01 PM   #8
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You are walking on the edge.

While the AC might work by itself, but as you add additional load from other items and reduce the voltage the AC will sustain internal damage due to heat.

The best thing you can do is get and install a volt meter in your trailer and watch it. If the voltage drops below 110 turn the AC off.

I am surprised your AC does not have a built in indicator for low voltage. Maybe another cheapping down of the Airstream brand.
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Old 12-16-2008, 05:27 PM   #9
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You can buy a cheap $12 AC voltmeter that plugs directly into any 110 outlet at a hardware or home improvement center. Keep it with the unit because sometimes the campground circuits are not that good sometimes and you will want to keep track that the voltage does not fall below 105 volts AC.
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Old 12-16-2008, 06:17 PM   #10
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why?

that wouldn't be "code", then, would it?

Though it is code, simply put, the standard outlets are rated 15amps. I would guess that with a fridge and A/C or even the A/C alone, depending on what size, the outlet itself would be exceeded. Household outlets were designed for a fridge, TV, entertainment system, etc. There are dangers even in a house overloading the outlet. In addition if I am correct, code now dictates several circuits in a home, compared to the 50s designs were in fact several rooms were on the same 20a circuit.

Bottom line, it's not a best practice to load up on a 15a outlet. A 20 amp residential circuit is mainly designed, if designed and deployed correctly to be spread over several outlets, unless in fact it is a higher rated outlet. Of course, in the end, it's your Airstream, if you need a new rooftop A/C unit prematurely, at least you'll know why.

I am going to put a 30a out to my garage, until then, my 15k BTU A/C unit remains either off or in fan only mode.
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Old 12-16-2008, 06:22 PM   #11
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The point I was making.
We're in total agreement.
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Old 12-16-2008, 06:38 PM   #12
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You can buy a cheap $12 AC voltmeter that plugs directly into any 110 outlet at a hardware or home improvement center. Keep it with the unit because sometimes the campground circuits are not that good sometimes and you will want to keep track that the voltage does not fall below 105 volts AC.
It's best to monitor the 110 volts, and not run A/C at a low voltage, regardless of circuit breaker ratings. Sometimes there is line loss due to bad connections etc. even though the line has a high amperage rating.
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Old 12-16-2008, 06:39 PM   #13
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We're in total agreement.
Thank you, my friend.
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Old 12-16-2008, 09:00 PM   #14
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just skip the line power entirely

Nominal 120v 20a circuit starts and runs any appliance in our trailer. Sometimes we forget and run the microwave with the space heater already on. Voltage stays within tolerance, appliances perform fully up to expectation.

Air conditioner, microwave, fridge, all are designed to operate normally on 120v +/- 10%. Power company specification is no tighter than this and doesn't need to be. This means a range of 108v to 132v, seems too broad but it is the design spec for the motors and other components in our appliances.

Agreed we should have a/c power meter to monitor conditions. And guideline for unplugging (or just turning off) things below 110 volts, while very conservative, can't hurt. I'll stay off the a/c power entirely if above 130v, too.

Heck, if we don't need the microwave we're much better off without line power entirely. Well, we like saving propane so the ceramic heater and fridge electric element are nice to have. Okay, I like line power when it's within tolerances.

Good discussion here.
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