The 20 amp shore power debate

[HeadnOut]

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
Head N Out

[Mike Leary]

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.

[Jim Foster]

Originally Posted by Mike Leary

We need spell check on this forum.

If you use Firefox as your browser, it will spell check for you on any forum.

[Silvertwinkie]

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.

[Mike Leary]

Originally Posted by Silvertwinkie

in all likelyhood the outlet is a 15amp outlet, further compounding the issue.

The point I was making.

[Chuck]

Originally Posted by silvertwinkie

Keep in mind that although your circuit may be 20amps, in all likelyhood the outlet is a 15amp outlet, further compounding the issue.

Originally Posted by Mike Leary

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.

[ROBERT CROSS]

Originally Posted by Mike Leary

We need spell check on this forum.

Why?... Nothing rong with the one we got.

[HowieE]

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.

[dwightdi]

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.

[Silvertwinkie]

Originally Posted by Chuck

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.

[Silvertwinkie]

Originally Posted by Mike Leary

The point I was making.

We're in total agreement.

[rogerdodger]

Originally Posted by dwightdi

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.

[Mike Leary]

Originally Posted by Silvertwinkie

We're in total agreement.

Thank you, my friend.

[DreamStreamr]

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.

[3 Dog Nite]

Let's assume that everything is correct right up to the outlet. That is a 20 amp breaker, 12 guage wiring, & 20 amp rated outlet. You have 20 amps available. A rule of thumb is to have a safety net of 10%. So now you are down to 18 amps of power available. (10% of 20 amp = 2amp, 20 - 2 = 18 amp) Be sure to use an extension cord made with 12 gauge wire. If it's like most, it's only made with 14 gauge wire. 14 gauge has a rating of 15 amps before your safety 10% reduction. Any cord over 50' should be 10 gauge due to the longer distance the electricity has to travel. When the A/C compressor kicks on, it will appreciate having the 10% available to keep the voltage up temporarily. If you don't have any voltage testers, feel if the cord & plugs to see if they are warm after you've been using it. Do this after about 1/2 hr. You'll be touch a lot of metal in the AS. Don't use a cord without a proper ground. I've often plugged into the 20 amp dedicated outlet for my pool's pump. Just be sure to turn pump off 1st. I tripped the breaker a couple of times forgeting about that.