120v on 30 amp enough for running a/c?

[johnpsz]

Here is my experience over the last few days of hooking my 30 amp RV up to a 20 amp circuit to run the AC, and it proves using the right wiring. When we first hooked it up we used a 30 amp household (15-20 amp plug) connector that we got with the camper as part of the dealer prep package and I have a cheap 100' extension cord (like 10 year old orange cord used a million times) that is on a real in my garage that I use for the electric leaf blower and hedge trimmers and etc. Anyhow, I figured I would just real that out to the trailer since the garage outlet was a 20 amp circuit (extension cord was only rated for 15 amp I believe, as most cheap ones are) and looking at my electrical panel on the RV the AC was on a 20 breaker so it should never really need more than that. Within 4 minutes of plugging in and starting the AC the breaker in the garage popped, I went the the garage reset the breaker and within a minute or less it popped again. My DW was a little upset because it was just under 100* outside and we had just had the trailer delivered the day before and she wanted to look around in it and it was very warm inside. I told her that I wanted to try a different extension cord on the same circuit and grabbed a 20 amp (thicker gauge wire) 20' extension cord and plugged it in and it was just about 2' too short to connect, luckily I also had a 25' one with the heavier gauge wire as well and hooked that one up. So now the trailer goes down my 20' 30 amp cable, down to the 1 foot 30 amp to household power connector, to a 25' heavy gauge extension cord hooked up to a 20 amp circuit. I went out and turned on the AC and it worked and never popped the breaker, I then noticed that the camp fridge is on AC only so as soon as the unit was plugged in it was cooling off too as well as charging the 12v batteries. So it seems like the correct size (both length and gauge wire) are essential for hooking up to a lower amperage outlet, and our trailer running with the system above can run the AC, camp kitchen fridge, charger for the 12v, and the TV without getting hot or tripping the breaker, but then again those were the only 110 items I tested at once.

 

[SeattleLion]

I regularly run my 15,000 BTU AC from a 20amp 125v circuit at home. Just be sure to turn off the electric hot water heater. If you do that, you will be fine.

 

[scottyb]

I bet you were pushing the 20A to it's max. The only way you accomplished this was since you minimized line loss with large cords. I learned like you about the cheap 100' extension cord connected to a 15A plug, and I didn't even have the AC on when it popped the breaker. Probably the Converter and the fridge, along with the line loss of the small 100' cord caused the amps to go too high. I ran the 50A cord all the way to the receptacle and it never popped again.

 

[Jim.Allison]

Exactly!!!!! mine will do well with both AC's on. I can even run the 1400 watt microwave because of the inverters ability to assist and distribute at will. But the water heater is the kicker. It is what it is, an "energy consumer. What I learned is that the larger AC unit is on the same ventilation system as the smaller one. If you close the door on the bedroom (Big Country) it will cool but mostly leaves the AC in the living room to cool the main part of the fiver. Later on when you hit the sack you can turn everything off except the two AC's and you will be fine.

I regularly run my 15,000 BTU AC from a 20amp 125v circuit at home. Just be sure to turn off the electric hot water heater. If you do that, you will be fine.