50 amp to 30 amp question

[Mroe67]

We have a 3120RL we have two a/c units but no instructions or plate showing amp draw, and don’t have my amp meter with me to check. So I was wondering, I understand they design the units with 50 amp service, but they do make adapters from 50 to 30. Dare I camp and plug into a 30 amp post? Would I chance burning up the adapter and 30 amp receptacle? I suppose if the draw was high the 30 amp breaker wouldn’t hold. Has anyone tried this?

[chuckster57]

Generally accepted rule is plugged into 30A, only 1 AC operating.

50A service is sort of misleading, as there are 2 legs of 50A for a TOTAL of 100A. In a 50A unit, the AC’s will be on opposite legs so you’ll have enough amps for everything.

AC unit will draw up to 18A at startup and operate at about 13A.

[notanlines]

There will be longer, more technical replies, but in a nutshell RVers do the 50 to 30 with an adapter all the time. Run one AC at a time. Lay off the microwave and blow dryer use. Run both the AC’s and the microwave? Nope, trips the circuit breaker.

[Fishsizzle]

There will be longer, more technical replies, but in a nutshell RVers do the 50 to 30 with an adapter all yhe time. Run one AC at a time. Lay off the microwave and blow dryer use. Run both the AC’s and the microwave? Nope, trips the circuit breaker.


What’s he said

[GHen]

Agreed with above, here is some basic math, although not completely accurate , if the AC startup is 18amp and they both start at the same time, 18+18 =36, and you’re trying to plug into a 30 amp plug. Might work, or sparks could fly (an exaggeration).
My suggestion, stick with the 50 for 2 AC units

[5J's]

As notanlines stated. One A/C at a time and you'll be fine.

[travelin texans]

And ALWAYS use a good quality surge protector/ems EVERY TIME you plug in, portable or hardwired, too many delicate electronics on modern day rvs. So a 30 to 50 dogbone adapter is definitely required if you rv is 50 amp.

[opienva1]

I have ran 2 ACs on 30 amp. You let one start and get running then turn the other on. I have also kicked a 30 amp breaker with 1 AC and the water heater running. So now when on 30 i always run the water heater on gas.

[edward willis]

Why not use a cheater?

[chuckster57]

Why not use a cheater?


What is a “cheater”?

[cookinwitdiesel]

The 30 amp (post) to 50 amp (RV) adapter will share the same 120v across both legs on the 50 amp RV end. Due to this, what is normally 100 amps @ 120v is only receiving 30 amps @ 120v. This allows all plugs and circuits in the 50 amp RV to be used however, you need to keep total draw under 30 amps total (regardless of what leg the device in the RV would normally use with the 50 amp service).

Now, all of that being said, you CAN run 2 ACs in 30 amps but as noted, need to stagger their start. Keep in mind there are other things that are always on in many trailers such as a residential fridge or converter charging the batteries (or ANYTHING plugged into a 120v outlet).

I only have a 30 amp 120v post at my house where I keep my trailer and it is plugged in with the requisite adapter right now. I happily operate both ACs (and the residential fridge) but nothing else without a problem so far. I haven't plugged in the EMS yet (home wiring is sound :) ) but should do so, I am curious to see what the amp draws are.

[edward willis]

A cheater is a device shaped like a Y. Looking at the top of the Y, one side plugs into 30 amp and the other side plugs into the house outlet at the post. Then you plug into the tail of the Y and there you go. Got mine at CW

[chuckster57]

A cheater is a device shaped like a Y. Looking at the top of the Y, one side plugs into 30 amp and the other side plugs into the house outlet at the post. Then you plug into the tail of the Y and there you go. Got mine at CW

Thanks for the explanation, haven’t heard them called that before.

[Roscommon48]

yep, your adapter will get hot, really hot. i've melted a few.

[Daryles]

This is a side topic but the response has a diagram of how rv uses 50A. https://www.rvtravel.com/can-i-use-a-welder-outlet-for-50-amp-rv-power/

[Daryles]

Another useful link http://www.myrv.us/electric/

[cookinwitdiesel]

Good concise article. There is a discussion on a FB group I am in that scares me to death where people with extremely poor grasps of electrical concepts are giving advice as if they are experts (ps a lot of it is bad advice).

I wired up my own post at home and at some point will look into upgrading it from 30 amp to 50 amp (already has the larger 4 conductor wire in place, only 3 conductors in use at the moment).

[Daryles]

I wired in a 14-50r https://www.amazon.com/Talon-LGP1S-Enclosed-Outdoor-Receptacle/dp/B00M3H6494/ref=asc_df_B00M3H6494/?tag=hyprod-20&linkCode=df0&hvadid=167135564802&hvpos=1o2&hvnetw=g&hvrand=11301837955349561190&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9020674&hvtargid=pla-307263286788&psc=1
With 6 gauge wire. Now I can run everything while it is sitting in my driveway.