Community Forums

sadrand · 02-27-2012, 12:14 PM

I am researching my first RV - I have decided on a motorhome. Most of the motorhomes I have been looking at are 50 amp, with 2 AC's. Many of the campgrounds I have been looking at offer only 30 amp. I know that you can hook up a 50 amp motorhome to 30 amp with the proper adaptor. What capability do you lose in the MH when you do that?

JimM68 · 02-27-2012, 12:31 PM

You will lose the second (bedroom) a/c, not much else depending on the ems. You'll need to pay attention to current draw.... a 100 amp battery charger will suck 12 amps easy. Microwaves, washing machines, hair dryers, coffee makers, all at considerable power.

You can "almost" run both a/c's on 30 amps, if nothing else is using power.

firedoc · 02-27-2012, 01:34 PM

We have been able to run both ac on 30a by paying close attention to what else is running. They make an adapter that you can use to run your 50 a coach on 2 30a connections. Works ok at a host site with an empty space but might cause some problems in a campground.

RickO · 02-27-2012, 01:36 PM

It's actually a bit misleading because you lose far more than just the 20 amp difference between the two titles because a 50 amp connection is actually TWO 50 amp legs at 120v. But, I agree with the above and think you'll only lose use of the second AC unit and maybe not even that if you're careful.

Rick

puttin · 02-27-2012, 01:39 PM

I have a 30A. coach. I also have a 50 to 30A. adapter for a couple of reasons. If there is an issue in the park with the 30A. (like a weak breaker)- I use the adapter. Also, there are some places that only offer 50A. (believe it or not).

LindaH · 02-27-2012, 03:00 PM

20 amps?

cbeierl · 02-27-2012, 04:22 PM

Quote:

Originally Posted by LindaH

20 amps?

Actually, the difference is 70 amps. The 50-amp connection provides a total of 100 amps of 120V power (2 legs x 50 amp ea.) while the 30-amp connection provides a total of 30 amps of 120V power.

You will almost certainly find that you can't run everything (at the same time) on the 30-amp connection. Depending on your coach you may or may not be able to run both A/Cs at the same time, and you'll probably want to run your water heater (and maybe your fridge as well) on propane to free up power for other things.

Lincolnboy2 · 02-27-2012, 04:35 PM

Yes, and I read somewhere the diff between 30 and 50 is a lot more than the amps. A 50 amp coach I think I read you get about 12,000 watts and in a 30 amp about 3600 watts of power....

Wizard · 02-27-2012, 04:40 PM

Although you will lose the use of that 70 amps, most coaches probably never use more than about 40amps anyway

pdq_bc · 02-27-2012, 05:22 PM

hi sadrand

welcome to the forum

i am not too electrically literate, but let me see if i can explain it in my words

not sure about the motorhomes you are looking at, but with ours...
we are 50 amp. when plugged into 30 amp, using the adapter, we really do not "lose capability" per se. the electrical management system (ems) 'manages' the available electricity. for example; if the fridge is running, and the microwave is running, and then something else is going to be running - the ems may turn off the fridge. as i said - the ems manages the electricity that is available based on the demand at any given time.

that said, we do watch what we use when on 30 amp. for example, we will not run the electric furnace, and the microwave/convection and the dryer all at once.

regards, pdq

mgscott4 · 02-27-2012, 05:57 PM

If you want to know exactly what you lose, just look at you circuit breaker panel. The 50 amp main breaker has a connected double pull handle, one is for "line 1" hot and the other is for "line 2" hot. Then every other breaker is fed from "line 1" and every other breaker is fed from "line 2" alternating. 30 amp service only line 1 so every other breaker is not hot on 30 amp.

On my rig, line 2 powers my rear AC and electric water heater. That is all I lose when connected to 30 amp or even 20 amp for that matter.

Pusherman · 02-27-2012, 06:22 PM

Quote:

Originally Posted by Lincolnboy2

Yes, and I read somewhere the diff between 30 and 50 is a lot more than the amps. A 50 amp coach I think I read you get about 12,000 watts and in a 30 amp about 3600 watts of power....

Exactly correct!! Amps is a measure of current. Watts is a measure of power.

So when on a 30A 120V circuit you have 3600 watts of available power.

On a 50A 240V circuit you have 12,000 watts of available power.

Now you can add up your draws:

Microwave = 1500 watts
hair dryer = 1000 watts
coffee maker = 600 watts
electric hot water heater = 1500 watts
converter charger = 120 - 6000 watts depending on how intelligent the charger is, and how much charge is being delivered to the batteries.
A/C each draw about 1440 watts

As you can see, a 30A 120V service gets used up pretty quickly.

**NLOVNIT** · 02-27-2012, 06:46 PM

Don't let 30a campgrounds scare you away from getting a 50a coach. We often RV with 30a hookups. Only a couple times it was so hot/humid I needed to run both A/C's at the same time. With careful monitoring & putting the fridge & HwHtr on propane, you'll be able to comfortably enjoy a 50a coach on 30a.

Lori-

cbeierl · 02-27-2012, 07:18 PM

Quote:

Originally Posted by mgscott4

If you want to know exactly what you lose, just look at you circuit breaker panel. The 50 amp main breaker has a connected double pull handle, one is for "line 1" hot and the other is for "line 2" hot. Then every other breaker is fed from "line 1" and every other breaker is fed from "line 2" alternating. 30 amp service only line 1 so every other breaker is not hot on 30 amp.

On my rig, line 2 powers my rear AC and electric water heater. That is all I lose when connected to 30 amp or even 20 amp for that matter.

This isn't correct when using a 'standard' 30-amp male to 50-amp female adapter. The 30-amp hot and neutral leads are connected to both legs of the 50-amp cable, therefore supplying power to all circuits in the RV.