2 AC's and 30 amps

[wags999]

Originally Posted by Hohenwald48

Actually, the OP never said if their trailer is wired for 50A or 30A service. I assume that with two A/C units it's wired for 50A service.

Either way, Wags999, the entire trailer will have power regardless of weather the OP is connected directly to a 50A service or connected to a 30A service via an adapter. The 30A to 50A adapter will connect the two legs together. Connected to 50A service he will have two legs of 50A each.

The 30A/20A to 50A adapter (shown above) does not tie the two legs together so the OP (assuming the trailer is wired for 50A) would only have 30A on one leg and 20A on the other leg. Normally, one A/C is connected to each leg. Some even had separate thermostats so that when the front A/C reach the set point and shut off the rear A/C would then run until it reached the set point then the cycle would repeat.

If the OP's trailer is only wired for 30A then no adapter would be necessary and the A/C units would need to be toggled from one to the other. In the old days, before 50A service was readily available, some manufacturers installed timing devices between the two A/C's that would automatically toggle the A/C's every half hour or so.

That's not always the case, I know for sure on several rigs only one AC got power when using the 30amp adapter on the 50 amp cord. I have to think about it, but, if they tie both legs of the 50 amp to the 30 amp leg, then you have power unbalance in the neutral wire. I'll see what I can dig up, either way, your still only going to have 3600 watts of power available.

[klassic]

Originally Posted by norty1

I have one of those and it will not work if it is on a GFCI or the 20a and 30a are on the same phase. I use it when I can in parks that are wired for it, like Georgia sp's. They have 2-30a feeds that are correctly wired in the pedestal.

The 30a to 50a adapter puts the 30a on both 50a incoming legs so everything will work until you exceed 30a.

Running 1 ac is part of the adapting.

It won't work on a GFCI, true...but I don't know why you are having a problem when the 30 and 20 are on the same phase.
That's like saying half the breakers in your house that are on the same buss bar of one phase in the breaker panel don't work because they are on the same phase.
They are on the same phase and share the same neutral.
In your trailer your feeding half breakers with 30a and the other half with 20a of the same phase sharing the neutral.
Your just not going to get 240v and you don't need to.

[klassic]

Originally Posted by wags999

That's not always the case, I know for sure on several rigs only one AC got power when using the 30amp adapter on the 50 amp cord. I have to think about it, but, if they tie both legs of the 50 amp to the 30 amp leg, then you have power unbalance in the neutral wire. I'll see what I can dig up, either way, your still only going to have 3600 watts of power available.

You're over thinking it.
On a 30 to 50 adapter your sending one phase 120v through two wires to the rigs breakers.. There is no "2 legs" or phases. It's all one phase. Just split by two main breakers at the trailer. The neutral will be balanced just like it is in a 30a rig.

The only time there might be trouble is having a 50a campground service receptical with both legs on the same phase and you max out both sides of your trailers 50a panel. Then you probably would over heat the neutral.

[Hohenwald48]

Originally Posted by wags999

That's not always the case, I know for sure on several rigs only one AC got power when using the 30amp adapter on the 50 amp cord. I have to think about it, but, if they tie both legs of the 50 amp to the 30 amp leg, then you have power unbalance in the neutral wire. I'll see what I can dig up, either way, your still only going to have 3600 watts of power available.

The only way that could happen is if the rig was equipped with something like an Intellitec power management system. These systems detect power available vs power being consumed and turn off/on RV appliances based on a priority table programmed into the system. They are common on high end motorhomes and I suppose could be found in some 5th wheels and travel trailers.

Power unbalance in the neutral wire is of no consequences since the neutral wire of a 50A RV is perfectly capable of handling a 100% unbalanced load from a 30A shore power supply. The 30/50 adapters do tie both legs of the 50A RV together. Get out your VOM and check it out.

[Edd505]

I know nothing of amps, phases, legs, etc but I do know my 50amp 5W has two A/C units and I am able to run either on a 30amp cord but not two. If the outside is cool enough I only run one so I don't have to get out the heavy 50amp cord. Just be aware of what you are using. Want the MW? Shut down the A/C while it runs.

I also run the bedroom during the day and the main at night so I am in the opposite space and the A/C is quieter.

[namusmc65]

As to the outlet that not much air is coming out of, you might want to pull that outlet down and take a look inside as much as you can. I have found all kinds of debris in my outlets!

[estesbubba]

Got my camper back from the dealer and 2nd AC wasn't hooked up correctly and service guy said it wouldn't have cooled. Glad I got that fixed before summer.

When running either unit on fan only the low and high settings don't change the speed. Does the speed only work when in cool mode?

[namusmc65]

Originally Posted by wags999

After thinking about this for a while it dawned on me, you probably will have no power coming to the secondary AC while on 30 amp service. You have a single leg of power coming into your unit when on 30 amp and typically they will have the main AC on that leg...the other leg is dead. May be a moot point as to when to run which..

Don't think that is so Wags. I'm on 30 amps in a lot of parks, and I can run either AC. Just not both at the same time. I'm wired for 50 but also have a 30 amp site at home. Can run either AC there as well. Sometimes do when we are loading up for a trip. Not as often any more though after putting up my shed for the unit. Does not get near as hot in it now.

[norty1]

If you use a 30-50 adapter to power your 50a rig, everything gets power as it always does. Only problem is it is only 30a. Soon as you draw that the breaker will trip at the pedestal.