Just bought my first Motorhome HELP!!!

Just got a new dryer - 4 prongs on the plug, fits nicely into the wall outlet I installed 30 years ago.

Open up that 12 volt switch, use a meter to make sure it is only 12 volts, and watch where it heats up when switched on. The multimeter (at least the voltage ranges) is the RV owner's helper. If unfamiliar with use of the meter, find someone who for sure knows and get a good demonstration. Any good teacher will watch you make some measurements after the demo because you need to do it yourself to learn. Leave current measurement for later - many people wreck the meter while trying to figure it out.

ga80486 wrote:

tjfogelberg wrote:
Most MH need 30 or 50 AMP service. Don't plug an RV into a regular household 20 AMP plug.

What? Mine is plugged in to a household outlet all summer when we're not traveling. Charges batteries, runs the fridge and one air conditioner.

I'm pretty sure 20 amp electricity looks the same as 30 amp electricity.

Thanks for clearing that! Will be buying in a few years and reading to learn as much as possible.

Chris Bryant wrote:

Dave H M wrote:
Doug, since we are off topic I just went and checked my 240 drier plug. It is three prong.

yeah it could be upgraded to four prong but I don't give a flip about the new codes and I would hate to think of trying to get a four wire from the service to the plug.

So in my case that first sentence does not apply. i don't know but if i had a four wire what would be the diff?

You are really playing with fire- you have 2 hots with no neutral using the ground as a current carrying conductor- not a good idea. They used to allow that for ranges and dryers as the 120 volt loads were small- clock and lights.

The issue is TWELVE VOLT LIGHT SWITCH. Every Christmas tree series string load after this switch is turned on AND there is a dangerously loose, bad connection at this switch. You MUST remove switch and meticulously check each and every connection and wire.



I have seen 55 volts line to earth ground and 230 volts line to earth ground.

DAMMIT! Neutral is NOT EARTH GROUND!

Neutral is the CENTER TAP of your service drop transformer on your private power pole. 12.5 KV to 240 X1, X2 and XO. Look at the transformer. Your power company did not install a transformer with an X0 tap for jollies.

A good rain can change L1 to Ground values 50 volts or more. Do you REALLY want to connect to such a flaky source?

Thanks for beating me up with a wet noodle Doug. :B

I hope you feel better now. :h

Eddie,

This Thread has veered way off course....

The lights in the bathroom are almost certainly DC, so disconnecting the shore power should make no difference.

Switches get hot for two reasons:
The switch is going bad.
The connections are loose. This is the more common issue.
I suggest that you go back onto shore power (a 15 amp receptacle is just fine as long as you don't do much (No water heater, A/C or microwave).
Then, get the switch out of the wall or fixture. If you can do this with the light off, that would be best. First, Check that the wire connections are solidly attached. If not, Fix that. Then, turn the lights on. Does the switch still get warm?
If the connections are solid and the switch gets warm, go find a replacement. It may not be bad now, but it won't take long.

Matt

Dave H M wrote:
Doug, since we are off topic I just went and checked my 240 drier plug. It is three prong.

yeah it could be upgraded to four prong but I don't give a flip about the new codes and I would hate to think of trying to get a four wire from the service to the plug.

So in my case that first sentence does not apply. i don't know but if i had a four wire what would be the diff?

I KNEW I would open a can of worms, just like I stated. The fact you asked the question shows you do NOT know. Others have already answered that question for you. It is off topic, but I do not like when people post bad info regardless of the topic. That is how urban bad info gets out there. The good news for me is, since MOST do not know 30 and 50 amp correct wiring for RV's, it keeps me in the money every year, year after year. Probably Chris also. Doug

Regardless, if you have a modern 4-pronged 220V outlet in your garage for a welder or a dryer, it is COMPATIBLE with the 50A plug on a Class A RV.

One common mistake people make is wiring up a 30A RV outlet as if it were an older 3-prong 220V welder/dryer outlet. That's BAD. It will fry your RV in short order.

Odds are the original poster probably just has a bad connection in the 12V light switch. Unplugging the RV won't prevent heat buildup because it is pulling the electricty off the battery.

MrWizard wrote:
Yes there is a difference.. Between 3 wire 220v and 4 wire 220v

But residential 4 wire 220v is all the same power

Not to be confused with 3 phase 4 wire which does not use a neutral
Just ground and three hots

Yeah, of course there is a difference between the older three wire and the now code-correct four wire receptacles. AFIK, the OP's motorhome and all RV 50 amp shore cords all have four prongs. All new installations and previous four wire 240V in residences all have four slots on the receptacle.

I'm trying to define this like I did in my original post as the previous posts in this thread had either misinformation, a misunderstanding, or the poster didn't read through the OP's post of having 50 amp service.

I'm hopeful that I'm not adding to the confusion but trying to eliminate some of it.

Yes there is a difference.. Between 3 wire 220v and 4 wire 220v

But residential 4 wire 220v is all the same power

Not to be confused with 3 phase 4 wire which does not use a neutral
Just ground and three hots

dougrainer wrote:

westend wrote:
He has 50 amp service in his motorhome. The 50 amp receptacle for shore connection is exactly the same as a 240V 50 amp receptacle used in residences for dryers, welders, or any other 240V device.

Heat usually means resistance. That can be from a loose or corroded wire on the switch. If the switch is a dimmer, it would be most likely that is the problem.

An excessive draw can also heat up devices not rated for that current but you would have to add a lot of lights or much bigger ones to exceed most 12 V switch ratings.

I am assuming that the switch is the same one installed by Newmar and not a homeowner replacement.

Your first sentences are absolutely WRONG. PERIOD. I am sure others will chime in. Doug

I don't believe so but maybe should have inserted "four pronged" into the description of the receptacles. I'm sure the OP has exactly that, both on the end of his cord and in the garage. Am I missing something? I can take pictures of my Marinco cord and the receptacle I have in the garage if there is confusion.

Online reference with picture of receptacle in pedestal