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Open Roads Forum  >  Travel Trailers  >  General Q&A

 > A/C on 20 amp

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Huntindog

Phoenix AZ

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Posted: 06/28/19 10:32pm Link  |  Quote  |  Print  |  Notify Moderator

Make sure that your guests understand the limitations of your power supply!. IOW, they know NOT to turn anything else on.
Takamine wrote:

Thanks all. I've got a wedding coming up this summer and may need the trailer for housing some of the bridal party.



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afidel

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Posted: 06/28/19 11:07pm Link  |  Quote  |  Print  |  Notify Moderator

MitchF150 wrote:

Are you using any kind of extension cord to plug in? If so, make sure it's a beefy cord and not just your everyday orange one that's 50' long!

If you do, you'll lose a lot of volts and it will get hot pretty quick.

If you are connecting directly from the 30a trailer cable to the adapter to the outlet, you should be fine as long as you don't run anything more than a few lights.. No water heater on electric, no fridge on electric, no microwave and no hair dryers for sure!!

Good luck!

Mitch

50' of 16 gauge wire @120V with 18A of current is only 7V of drop, add the 1V of drop from 25' of 10 gauge RV cord and you're still at 112V, plenty. You'd only have a problem if the source voltage was 115V in which case you'd be close to the minimum for most motors. Step up a few dollars to a 12 gauge extension cord and you're under 4V of total drop which should be plenty even at 115V source.


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westend

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Posted: 06/29/19 12:54am Link  |  Quote  |  Print  |  Notify Moderator

We don't know how long the total circuit is from distribution box to trailer inlet so advice on cord length and gauge is problematic. One of the better things you can buy for your RV'ing (and other household use) is a Kill-a-watt device. One side is connected to the power source and the KAW has a receptacle for the device needing power. Mine will measure amperage, voltage, and watts consumed. Handy thing to have around when there is a question of amounts of power needed and what is happening inside the copper wires.

FWIW, I power a table saw with a longer cord. I bought a length of 8 AWG and attached an industrial male plug to the cord. I've never measured the power consumed since it has never tripped a breaker or sagged under the biggest loads. I mention it as an example of how larger wire gauges can bring reliability to the application.


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JRscooby

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Posted: 06/29/19 04:54am Link  |  Quote  |  Print  |  Notify Moderator

My AC plugs into a 20 Amp plug on a 20 amp breaker in the camper. When I want to run AC at home I pick up power at the outlet near home breaker box, (on 15 amp breaker) and run the cord to the AC.

Bumpyroad

Virginia

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Posted: 06/29/19 05:58am Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

Monitor the voltage my comfort zone is 107 volts and up.


the most important factor IMHO
bumpy





RoyB

King George, VA

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Posted: 06/29/19 06:52am Link  |  Quote  |  Print  |  Notify Moderator

Do this at home in the back yard all the time... I have a 20AMP Circuit in my garage that used to be an air compressor station. It is the only thing on the house breaker. I use a long dog bone type adapter to plug my POPUP trailer shore power cord into the 20A Garage circuit..
[image]
Google image

I am not a big fan of the various small rubber and plastic adapters you find on the market as they will get hot on me a lot of the time...

[image] [image]
Google images


I have two commercial grade 50-foot long YELLOW Contractor extension cords that I picked up from a yard sale a few years ago...

Inside my POPUP trailer I have one of these plug-in AC VOLTMETERS that has a safe zone marked on the meter display... Easy to spot when the AC Level is too low to use the air conditioner...

[image]
Google image

I can run everything in my OFF-ROAD POPUP off of the 20Amp Circuit but have to watch what is on at the same time of the higher wattage items... If I draw too much it will pop the garage breaker in the house...

Roy Ken
[image]

myredracer

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Posted: 06/29/19 09:30am Link  |  Quote  |  Print  |  Notify Moderator

Takamine wrote:

When I'm at home, I use an adapter and plug my TT into a 20 amp outlet. I've heard that you shouldn't run your A/C when only plugged into 20 amps, but the breaker for the A/C in the TT is only a 20 amp circuit. Should there be any issue running the A/C with only 20 amps, if nothing else is running? Thoughts?

Thanks


*IF* nothing else is running, the converter can be drawing around 3-5 amps. AC units draw in the 12-15 amp range depending on rating and make/model. So you could be drawing around 15 to 20 amps "if nothing else is running." Have you verified that the house wiring is #12 gauge or #14 and do you know how far it is from the receptacle to the panel?

Voltage is everything when running AC units. You should have a voltmeter inside your TT to monitor voltage. An LED type is more accurate and don't cost much. Voltage can fluctuate so don't assume it's always going to be okay. If it starts dipping below 110 volts, you want to pay attention. Note that AC units momentarily draw 50 to 60 amps on startup and voltage can dip very low, well below the 104 or so volts that can damage AC units.

Note that AC units draw more current as voltage goes down. So that 15-20 amps noted above go higher.

If you read manufacturer's specs, an extension cord over 50' should be at least #10 ga. Do NOT use a cheapo "heavy duty" extension or #14 or smaller gauge. "Heavy duty" means nothing at a retailer. The cheap connectors and plugs on low cost extension cords can get hot and even go up in smoke in some cases. Best thing you can do is find a high quality true heavy duty cord with MINIMUM #12 ga. Making one up from scratch is also a good option.

Always, always make sure the plug blades on your shore power cord and ext. cords are kept clean and shiny with sandpaper or emery cloth. And never plug in unless the power is turned off. Converters have an inrush current (due to capacitor charging inside) that causes pitting on plug blades and inside receptacles & connectors. The pitting attracts dirt and carbon, leading to a poor connection and overheating. In the very beginning, I had a couple of cheapo extension cords go up in smoke. Then I installed a 30 amp RV outlet in the carport.

Be aware that if you fail to monitor voltage and it frequently dips below around 102-104 volts, you can cause damage to the motor windings in an AC. The damage is cumulative over time and one day can fail for no apparent reason. New AC units are not cheap. And just because some people "do it all the time" doesn't mean you won't ever have a problem.


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Wild Bill 888

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Posted: 06/29/19 11:45am Link  |  Quote  |  Print  |  Notify Moderator

Verify no other big loads on the circuit like a room ac.

frisbeekev

Burtonsville, md

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Posted: 06/29/19 06:03pm Link  |  Quote  |  Print  |  Notify Moderator

We have guest in now and are plugged into a dedicated 20 amp circuit. We are running Ac it will cut off when gets to temp but won't cut on. Would this be a voltage issue or thermostat malfunction?

myredracer

Langley B.C.

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Posted: 06/29/19 07:35pm Link  |  Quote  |  Print  |  Notify Moderator

nev'r mind...

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