Forum Discussion

mustanglover32's avatar
Feb 14, 2017

Running A/C with extension cord into 20 amp outlet.

Trying to figure out if what I'm trying to run below is moving too close to the limits of a 20 amp 120V outlet and limits of a 12 gauge extension cord that is 25 feet.

Trying to run a 135K BTU A/C unit on my travel trailer.
Connect travel trailer to 30 amp to 20 amp dogbone
Dogbone connects to 12 gauge extension cord that is 25 feet
That extension cord connects to a 20 amp 120V outlet.

Nothing else in the travel trailer is run, no AC to DC converter, microwave etc.

First Question: Am I getting too close to the limits of the extension cord and 20 amp outlet?
Second Question: Should voltage drop be a concern, since there is approximately 40-50 feet of cable (travel trailer wiring + extension cord) between the outlet and the AC?

Using the 80% rating rule, 1920 watts is about the upper limit for a 20 amp service right?

Now, to be clear, I have actually tried this already and had no issues running the A/C for 4+ hours with the fan on high and the compressor was engaged for 90% of that time. The extension cord plug into the 20 amp outlet did get a little warm, but not enough to be concerning. None of the breakers ever tripped either.

I was not able to directly measure the wattage either, my kilowatt meter is only rated to 1800.

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