Community Forums

CaptVideo · 06-11-2021, 08:17 AM

I think I know the answer but is there any issue with plugging my 30 amp trailer into a 50 amp plug (with an adaptor plug)? This came up while camping at a KOA. Several times during a 90 degree day, the AC tripped the 30 amp circuit on the power post. There was also a 50 amp plug on the post and I got to wondering if I plugged into that, would it handle the AC better? (I don't have the adaptor plug yet.)

Cumminsfan · 06-11-2021, 08:30 AM

I did it once. The CG I camped at only had 50A posts. I had to run into town and get an adapter. Haven't used it since.
Look at it this way. It's no different than plugging in to a 20A plug vs a 15A plug at home.

JMitchell · 06-11-2021, 08:35 AM

Quote:

Originally Posted by CaptVideo

I think I know the answer but is there any issue with plugging my 30 amp trailer into a 50 amp plug (with an adaptor plug)? This came up while camping at a KOA. Several times during a 90 degree day, the AC tripped the 30 amp circuit on the power post. There was also a 50 amp plug on the post and I got to wondering if I plugged into that, would it handle the AC better? (I don't have the adaptor plug yet.)

As long as your TT isn't PULLING more than it's wiring can handle (30A) then it should be OK. I'd imagine that if the 30A breaker was tripping it was worn out more than you were actually pulling that load.

I have a 50A dogbone just for the case like the previous poster where only 50A outlets are at the hook up, have only used it once also, put that in, then my surge suppressor/power checker, then the extension to the TT.

**hamm2018** · 06-11-2021, 08:47 AM

Quote:

Originally Posted by CaptVideo

I think I know the answer but is there any issue with plugging my 30 amp trailer into a 50 amp plug (with an adaptor plug)? This came up while camping at a KOA. Several times during a 90 degree day, the AC tripped the 30 amp circuit on the power post. There was also a 50 amp plug on the post and I got to wondering if I plugged into that, would it handle the AC better? (I don't have the adaptor plug yet.)

The most you are going to use is 30 amps. Doing what you are thinking about is okay, but you will not get any more power. You may start tripping your breakers in the camper, which is no big issue. But to help avoid it, make sure other items are off, when running your AC. For example turn the water heater off of electric if you had it on electric, no microwave with AC, and or water heater on. I had a list of electrical draw for different items in the RV. If you would like I see if I can find it to help.

**hamm2018** · 06-11-2021, 08:56 AM

Here is a list of power usage I have:
AC 15,000BTU 12.5 amps
Electric water heater 6 gal. 12.5 amps
Microwave Oven 12.8 amps
Electric coffee pot 9.0 amps
Toaster 10.0 amps
Hair Dryer 10 amps
TV 2.0 amps
Electric frying pan 10.0 amps
Crock Pot 1.5 amps
Heating pads .5 amps
Food Processor 8.0 amps

The paper says this is the average amps for use
To figure out amp draw:
If you know the watts divide the watts by 120 volts = amps
Multiply the amps by 120 volts= watts

I picked this up at a campground a couple of years ago, so the numbers could be out of wack, compared to the new appliances of today, but it should still be a good rule of thumb.

KanzKran · 06-11-2021, 08:56 AM

I've used my 50A a couple of times, mainly when the 30A receptacle was worn out and loose. And breakers do tend to open at a lower threshold as they age and are overloaded many times. And possibly when sitting in the sun, since it's the thermal portion that opens it on a sustained but relatively small overload. Better it opens on a lower rather than higher load.

Coach main breaker will still limit you to 30A, of course.

twinboat · 06-11-2021, 09:07 AM

Quote:

Originally Posted by hamm2018

Here is a list of power usage I have:
AC 15,000BTU 12.5 amps

I picked this up at a campground a couple of years ago, so the numbers could be out of wack, compared to the new appliances of today, but it should still be a good rule of thumb.

12.5 amps for a 15,000 BTU AC is a bit out of wack.

It may draw that on a cool day, but as outside temps climb, AC compressors work harder and draw more amps, up over 16 amps one a hot day.

KanzKran · 06-11-2021, 09:34 AM

Quote:

Originally Posted by twinboat

12.5 amps for a 15,000 BTU AC is a bit out of wack.

It may draw that on a cool day, but as outside temps climb, AC compressors work harder and draw more amps, up over 16 amps one a hot day.

Screen shot of a page (partial) from a Dometic manual showing FLA for compressors and fans. Lowest total is about 14A for an 11,000 btu unit, and highest is around 16A. I'm assuming the Hi Cap units are 15,000 btu, but I don't know that.

Soooo, what twinboat said.

**hamm2018** · 06-11-2021, 09:41 AM

Quote:

Originally Posted by twinboat

12.5 amps for a 15,000 BTU AC is a bit out of wack.

It may draw that on a cool day, but as outside temps climb, AC compressors work harder and draw more amps, up over 16 amps one a hot day.

Just giving them an ideal of what to think about. I can't remember what the start up is on these units, can you?

KanzKran · 06-11-2021, 09:46 AM

Quote:

Originally Posted by hamm2018

Just giving them an ideal of what to think about. I can't remember what the start up is on these units, can you?

Easy. Add the LRA for both the compressor and the fan, from the table I posted. Since both motors are stationary at the time power is put to them, they're in a locked-rotor state, and act essentially like two big resistors of just a couple of ohms combined.

Once they get to somewhere around 75% of rated speed (typical of induction motors), which happens very quickly I might add, back EMF starts having a real effect and current drops off fast. But for most of the short start-up cycle, the unit is drawing very high current. It just happens too fast for the typical clamp-on meter to fully register.

wolfe10 · 06-11-2021, 09:48 AM

Quote:

Originally Posted by KanzKran

I've used my 50A a couple of times, mainly when the 30A receptacle was worn out and loose.

Coach main breaker will still limit you to 30A, of course.

Yup, main reason for using the 50 amp outlet with a 30 amp RV.

TXiceman · 06-11-2021, 11:32 AM

RV main breaker is still a 30 amp breaker and the RV is protected. When you use a 50 amp plug at the electrical box, with a 50 to 30 adapter, it is only connected to one of the two 120 volt legs. The wiring in the park is supposed to balance the 30 amp loads between the two legs by alternating L! and L@ for the 30 amp connection. Often the 50 to 30 amp adapter will put you on the less loaded leg of the circuit and you will have a higher voltage at the RV.

You need to have a voltage monitor in the RV so that you can monitor the voltage you are receiving. Most RV A/C unit will not not operate below 108 volts when running. They draw excessive amperage and the motors will overheat and trip the unit on amps or the thermal overload in the compressor. To help the voltage situation, you need to put the fridge on gas and the water heater on gas. This will usually give you an extra couple of volts and may be enough to keep you running.

Voltage meter
This will show the volts in the unit.

Ken

sibe · 06-11-2021, 12:16 PM

Couple things..

On the pedestal the wiring in unbalnced when there is a 30 and 50.. Many times there is a 50 A a 30 and a 15/20 rect.. If wired proper these can almost balance if all were in use.. BUT the pedistal is in a connection with a few more in distribution that can casue a drop on one leg , plus the age of the breakers and box and the plugs..

My 15K on a warm day would run at 12.4-13.9 amps on low fan,, On a 90+ day it would see 14.3+, if compressor cycles expect a fast hit of 21-25 amps can happen... I mapped my power draw once tring to diagnose an issue that turned out to be a tired AC compressor..aka 1996 coleman..

Your Converter/Charger can add 1 to 3 amps to it easy when it is just hanging out.. My charge wizard has gone to high/desulficate during AC run.. that is over 3 amps.. My TV. microwave on stand by.. is another 1.3-2 amps parisitic

So some times if in a park and you have others tapping th e juice...wham

Boogie_ · 06-11-2021, 08:03 PM

Quote:

Originally Posted by CaptVideo

I think I know the answer but is there any issue with plugging my 30 amp trailer into a 50 amp plug (with an adaptor plug)? This came up while camping at a KOA. Several times during a 90 degree day, the AC tripped the 30 amp circuit on the power post. There was also a 50 amp plug on the post and I got to wondering if I plugged into that, would it handle the AC better? (I don't have the adaptor plug yet.)

I think I know the answer but is there any issue with plugging my 30 amp trailer into a 50 amp plug (with an adaptor plug)? Nope, you'll be fine.

There was also a 50 amp plug on the post and I got to wondering if I plugged into that, would it handle the AC better? Yep, did it for years on my previous 30 amp rig.