Can a 30amp A/C run on 20 amps?

By the way, I have a 50 amp motor home, when I had a sticks and bricks in put in a TT-30 outlet (Before I brought the RV home) and fed it with a 20 amp breaker and about 100' of 12ga.

No problems running one A/C with the batteries charged (As noted above with the converter in BOOST mode that did not work so well) did it most of the summer in fact when I went out to the RV to check into ham radio nets

or running one space (JUST ONE) heater in the winter.

Or the microwave

OR the water heater

Just never more than one of the above and only with charged batteries.

I am assuming he is going to use a converter plug to connect his 30 amp cord to a 20 amp outlet.

If that is the case, then don't be too surprised if there is, in fact, a problem. I connected my trailer to a 20 amp circuit, which gave me 10 amps per leg. When I tried to run a portable space heater off the 110 outlet in the wall you could almost count the revolutions the fan was turning, and it surely sounded like it was laboring b adly. If the A/C draws more than 10 amps he is SOL. Just my humble opinion.

In other words, whatever is at the pedestal, divide by two.

Thanks to all !

There's a LOT more information up there than you asked for.

The simple answer is that your son does NOT have a 30 amp AC. A 30 amp AC is a whole house unit, not a camper unit. He has a 30 amp TRAILER.

In practice, the AC will run fine on a 20 amp circuit. But he won't be able to run the AC AND the microwave, AND the overhead lights, AND his coffee maker without tripping the breaker.

Hi,

Depends on the distance from the campsite to the main meter.

At the main meter, there probably is 118 - 120 volts. 300' away with #12 wire, then the voltage drop with a 12 amp A/C load on that small wire, there might only be 105- 108 volts. So it really depends on the wire size and distance.

I would suggest a voltage booster. You will probably need it, or require it. Even a 12 volt boost might not be enough on a warm day.

My hope is that when they upgrade, they will put in #8 or larger wires! That is great for 30 amps at about 200' from the main meter, but any further, the resistance in the wire means you will still have low voltage. . .

I lived about 300' from the ranch house, and could count on a 12 volt drop when I ran my A/C unit. And they did have #8 wire from the house to the pump house, and I was plugged in to the pump house. I have a 12 volt booster, and used it all summer, but plugged in my refrigerator to the non-boosted receptacle, so I did not want it running on 132 volts when I was not running the A/C unit.

You MUST have a volt meter that can stay plugged in all the time. Look for a Kil-a-watt on E-bay for about $25. Plug in to a living room receptacle in the RV. When voltage drops below 105, then shut off the A/C unit. If voltage pops back up to 116 then you will know that you have a constant 11 or 12 (whatever it pops up by) voltage drop, and know that you will require a voltage booster. Without a volt meter, you are risking damage to the A/C unit. Your voltage will be very marginal - especially with #12 wire to each site.

#10 wire has a max fuse size of 30 amps, so likely they installed #12 wire and have 20 amp circuit breakers for each site.

Larger RV parks with 50 amp services use relatively huge wire - say #0 wire and then protect 10 - 12 sites with a 150 amp circuit breaker. #2 wire is good for 100 amps, and is almost the diameter of a pinky finger. #0 is larger than that! With #0 wire, there is practically no voltage drop in 100' and only 1-3 volts with a 300' long run. However the wire is a little over $2 per foot, and likely out of the budget for a small RV park that is just starting out. That is why they used #12 wire to start out with, and you have a huge voltage drop.

Good luck!

Fred.

Take a look INSIDE the RV at the power center, Find the breaker labeled for the A/C.. I will bet it is a 20 amp, so that answers your question.... Sort of.

Now.. If the power center is a combined 12/120 volt what make and model is it? If not what is the make and model of your converter?

Why do I ask this... MY converter plus ONE air conditioner run fine on 30 amps all day long unless I suck down the batteries with the inverter (Which I may do if it's hot enough out) And the converter kicks into BULK mode.. Then it draws like 10-12 amps and added to the 13.5 of the A/C and an older 30 amp breaker.. CLICK of darkness happens.

My converter is an 80 amp model.

So the solution.

AC or Water heater OR microwave but never more than one

Fridge on Gas will help (lock it in that mode)

Let batteries charge for a while before firing A/C if they need it.

And that will work.. I ran my entire RV on 20 amps when I had a sticks & Bricks.

Dutch_12078 wrote:
His A/C alone does not draw 30 amps, but more like 12 or 13 while running, with a higher momentary starting load. As long as the voltage is adequate, it'll run fine on a 20 amp circuit, although the amount and type of other items that can be used at the same time will be limited. The A/C would have to be shut off to use a microwave for example, but it is doable and done by many RV'ers, most commonly when plugged in at home.

dutch hit the nail squarely on the head. it all depends on the CG voltage at your pedestal. nominal voltage is 110/120 volts. as voltage decreases amperage pull will increase. ohms law says: amps = watts/volts.

let's say for sake of discussion the air conditioner is rated at 1400-watts and the voltage at the post is 110. 1400/110 = 12.72 amps. if the voltage at the post is 120 the air conditioner would pull 11.6 amps; 105 volts would pull 13.3 amps. all your son need to is determine the wattage of the air conditioner, measure the voltage at the post and do the math.

You can just buy a fan if the A/C turns out to be a problem for some reason. Summer will be over soon. No sense spending a lot of money on a work-around.

Hi,

He will need to monitor the voltage under load. I suggest getting a kill-a-watt meter to do so.

My comfort zone is 109 volts and up. At 107 volts I turn the air conditioner off, or move to my inverter.

If his voltage is low, he can add an autoformer to correct it.

As said, the actual voltage supplied is more important than the labeled number of amps. 20 amps, 30 amps, etc. in this case are more indicators of system design than what you might actually get. If the AC runs without tripping any breakers and you have at least 108 volts you will likely be OK>