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wagonmaster2 · 01-29-2015, 10:38 PM

I'm planning on having an electrician wire up a 50A box at our house for the RV. I've read that if the electrician doesn't understand how an RV wiring works a person can get 220V connected to the RV and fry things inside. Is this really true, and if so, are there internet instructions/pictures I can supply to the electrician to be sure he understands each leg of the 50A plug should be 110V? How is the wiring different that could have the RV connected to 220V?

I have no intention for doing this myself but I definitely want to be sure the electrician understands he's wiring 50A for 110V service.

I've seen pictures showing a hot wire connected at 3 o'clock, one hot wire at 9 o'clock, then negative and ground at 6 o'clock and 12 o'clock respectively. This is supposed to be right for the RV but what happens to give 220V?

Dennis4809 · 01-29-2015, 10:51 PM

The 50A RV outlet is wired exactly like any kitchen's 50A range outlet. Uses a 2 pole 50A breaker and will read 240V if you read across the hots. Your RV uses the legs separately hence the 110V.

The 30A RV is where the issue comes in. Old dryer outlets were 3 pins, 2 hot and a neutral giving the dryer 240V. The RV outlet is 3 pins but are 1 hot at 120V, other 2 are a ground and a neutral.

cbeierl · 01-29-2015, 10:53 PM

Here's are a few references:

The 50-amp 120/240-volt 3 pole 4

http://www.rvpowerprotection.com/Lin...%20Service.pdf

Arch Hoagland · 01-30-2015, 12:22 AM

This is what I bought and installed at my house. Works great and already wired correctly.

GE 100 Amp 3-Space 3-Circuit 240 Volt Unmetered RV Outlet Box with 50/30/20-Amp GCFI Circuit Protected Receptacles-GE1LU532SS - The Home Depot

wa8yxm · 01-30-2015, 06:36 AM

With a 50 amp outlet you should have no problem, it is only the 30 amp outlets that they have problems with.

To an electrician who does not RV the 30 amp outlet LOOKS like a 240 volt outlet used for some high power hardware like Air compressors, welders and dryers.. IT IS NOT.

But the 50 amp outlet looks like a 50 amp 120/240 volt outlet, which is exactly what it is, and thus they wire it correctly.

So since you are putting in a 50... Rest easy.

When he is done, have him voltmeter the outlet

Side to side 240 volts
Side to top or bottom (The center flat blade or the round/D shaped one) 120 volts.

wagonmaster2 · 01-31-2015, 04:09 PM

Thanks for that information, helps me a lot. I could remember that on the 50A outlet that either side slot connected to either top or bottom would read 120V but I couldn't remember if connecting side to side would read 120 or 240.

Wonder if it's less complicated to wire for 30A than for 50A or if it really doesn't make any difference other than the higher cost of the wire. But probably while I'm having it done should just go ahead with 50A since during the summer I'd be might be running the air conditioner, the residential frig, the convertor to keep batteries charged, and maybe the electric water heater off and on.

BFlinn181 · 01-31-2015, 04:22 PM

Give this diagram to your electrician and TEST the outlet before plugging anything into it.

EMD_Driver · 01-31-2015, 04:24 PM

Quote:

Originally Posted by wagonmaster2

Thanks for that information, helps me a lot. I could remember that on the 50A outlet that either side slot connected to either top or bottom would read 120V but I couldn't remember if connecting side to side would read 120 or 240.

Wonder if it's less complicated to wire for 30A than for 50A or if it really doesn't make any difference other than the higher cost of the wire. But probably while I'm having it done should just go ahead with 50A since during the summer I'd be might be running the air conditioner, the residential frig, the convertor to keep batteries charged, and maybe the electric water heater off and on.

The 30AMP 120v outlet uses three wires. Normally 10 gauge wire. It has a hot leg (120v) a neutral and a ground.

The 50AMP has four wires. Normally 6 gauge wire. It has two hot legs (120v each) a neutral and a ground.

The most common problem is that some electricians think a 30AMP RV circuit is 240v, which is not true. They will wire it as two hot legs and a ground. As soon as it is plugged into a 30AMP 120v RV, bad things happen and it is very dangerous.

The 30AMP RV plug HAS to be 120v.

The 50AMP RV plug is typical 240v wiring, but 99.9% of RVs keep the two hot 120v legs separated. It is only when you combine the two, that you get 240v out of it.

Residential electric stoves, water heaters and HVAC systems combine the two 120v hot legs and get 240v.

RVs keep both of the hot legs separate, so nothing will get 240v to it.

Sorry for the long-winded explanation.. I hope it helps..

gemini5362 · 01-31-2015, 04:33 PM

In your original post you used the term negative. That is incorrect and you do not want to confuse your electrician if you try to tell him how you think it should be. The correct term in Neutral. You do not have a negative in an AC system

FlyingDiver · 01-31-2015, 04:37 PM

Quote:

Originally Posted by EMD_Driver

The 30AMP 120v outlet uses three wires. Normally 10 gauge wire. It has a hot leg (120v) a neutral and a ground.

The 50AMP has four wires. Normally 6 gauge wire. It has two hot legs (120v each) a neutral and a ground.

The most common problem is that some electricians think a 30AMP RV circuit is 240v, which is not true. They will wire it as two hot legs and a ground. As soon as it is plugged into a 30AMP 120v RV, bad things happen and it is very dangerous.

The 30AMP RV plug HAS to be 120v.

The 50AMP RV plug is typical 240v wiring, but 99.9% of RVs keep the two hot 120v legs separated. It is only when you combine the two, that you get 240v out of it.

Residential electric stoves, water heaters and HVAC systems combine the two 120v hot legs and get 240v.

RVs keep both of the hot legs separate, so nothing will get 240v to it.

Sorry for the long-winded explanation.. I hope it helps..

I disagree with your 99.9% of RVs number. A lot of new/larger RVs have 240V residential dryers in them. So safer to never make the blanket statement that nothing in an RV is ever 240V.

RodgerS · 01-31-2015, 05:03 PM

Very nicely presented Gentlemen.

vsheetz · 01-31-2015, 06:51 PM

Quote:

Originally Posted by BFlinn181

Give this diagram to your electrician and TEST the outlet before plugging anything into it.

Great diagram. Thanks for sharing.

Arch Hoagland · 01-31-2015, 08:53 PM

I originally installed a 30 amp outlet thinking I wouldn't ever need 50 amps by my house.

We had a water line break in the house and we had to move into the motorhome for six weeks while the house was being repaired.

It was July and we have temps of 100 degrees here almost everyday during that time. My insurance company, AAA, agreed to upgrade my 30 amp to 50 amp service as we needed it to run our Air conditioners, etc.

So I'd suggest going with 50 amp.

vsheetz · 01-31-2015, 10:36 PM

I installed 30a outlet and breaker. But ran wire as if for 50a and allowed room for breaker upgrade. Saved a few dollars now, can easily upgrade if needed/desired in the future.