50A 120V RV Receptacle

[A/A Fuel GTX]

I have a client asking me to install a 50A 120V receptacle for an RV. I'm not real savy on RV wiring but all I can find in a 50A configuration is a 4 wire version which would be a 120/240V set up. Has anyone seen a 50A 120V receptacle:?

 

[kwired]

I have a client asking me to install a 50A 120V receptacle for an RV. I'm not real savy on RV wiring but all I can find in a 50A configuration is a 4 wire version which would be a 120/240V set up. Has anyone seen a 50A 120V receptacle:?

Any real good reason why they want this? Part of the idea of an RV is you can take it all over the place - they will not find any place to plug in their modified version except wherever you have installed this receptacle.

 

[A/A Fuel GTX]

Any real good reason why they want this? Part of the idea of an RV is you can take it all over the place - they will not find any place to plug in their modified version except wherever you have installed this receptacle.

Not sure. This guy sells used RV's and wants to be able to plug the RV into a receptacle so the potential buyer can see everything work. He says the RV's require the 50A supply. I'm in uncharted territory here.........

 

[jumper]

I think that even if a 50A 120V receptacle exists, it would not be allowed.

551.46(C)(4) Units with 50-Ampere Power-Supply Assembly. Recreational
vehicles having a power-supply assembly rated 50
amperes as permitted by 551.42(D) shall have a 3-pole,
4-wire grounding-type attachment plug rated 50 amperes,
125/250 volts, conforming to the configuration shown in
Figure 551.46(C).

 

[hillbilly1]

I think he is confused, a 50 amp RV receptacle is 120/240 (same as a range receptacle) There is a 30 amp 120 volt receptacle that is also used for RV's. There's nothing in the RV that requires 240 though, and some RV's have energy management systems that limit the load if a bootleg 50 amp is used. (30 amp dogbone adapter)

 

[A/A Fuel GTX]

I think he is confused, a 50 amp RV receptacle is 120/240 (same as a range receptacle) There is a 30 amp 120 volt receptacle that is also used for RV's. There's nothing in the RV that requires 240 though, and some RV's have energy management systems that limit the load if a bootleg 50 amp is used. (30 amp dogbone adapter)

Ok, so I would install a 4 wire 120/240V 50A circuit and when the RV is plugged in, it distributes the power correctly so 240V is not applied to anything that would subsequently cause problems:?

 

[kwired]

Ok, so I would install a 4 wire 120/240V 50A circuit and when the RV is plugged in, it distributes the power correctly so 240V is not applied to anything that would subsequently cause problems:?

In a nutshell yes, there is 120/240 supplied to the RV but there are no 240 volt loads on board. If you were to supply both ungrounded conductors from same "phase" and loaded them to the max you would double the current on the neutral but never overload the ungrounded conductors.

Outside of air conditioning, if this guy wants to just display units he likley would get by easily with 15 amp adapter on the cord. If it is desired to run the air conditioning long enough to maintain inside temperature, that will be too much load, to just turn it on for a couple minutes to show it works may still work with the 15 amp adapter.

 

[construct]

What 'hillbilly1' said. I ran a campground for 12 years and even in the large 45 ft coaches, nothing in them required 240v. The panels inside are set up with 2 legs of 120v and there are no 2 pole breakers.

 

[hillbilly1]

Ok, so I would install a 4 wire 120/240V 50A circuit and when the RV is plugged in, it distributes the power correctly so 240V is not applied to anything that would subsequently cause problems:?

Yes, you would not believe how many times I have corrected the wiring on the 30 amp 120 plugs where the homeowner and some of their electricians see "30 amp" and automatically connect it to a two pole breaker throwing 240 to the RV! Usually ends up frying the inverter, convertor and a couple of TV's!

 

[ElectricianJeff]

Yes, you would not believe how many times I have corrected the wiring on the 30 amp 120 plugs where the homeowner and some of their electricians see "30 amp" and automatically connect it to a two pole breaker throwing 240 to the RV! Usually ends up frying the inverter, convertor and a couple of TV's!

Can you explain further? I'm confused :?

 

[hillbilly1]

Can you explain further? I'm confused :?

The 30 amp RV receptacles are straight 120 volt, neutral, hot and ground. They are not 240 volt. Many shade tree electricians and homeowners think anything over 20 amps is 240 volts and wire them so not looking at the box.

 

[kgk1961]

Can you explain further? I'm confused :?

Jeff - It can get confusing, especially if you don't own, or have worked on, RV sites before. Luckly, I have done both.

Large RVs will require a 50Amp connection to operate everything in the unit; however since many campsites might not have the 50Amp service available, all the loads inside the RV are 120V. That way the RV owner can connection his 50Amp plug into a 30Amp receptacle (via the proper adapter) and can still operate the RV unit, just limiting his usage. (For example, many large units have two HVAC systems. The RV owner would be limited to running one HVAC unit at a time, or risk tripping the 30Amp breaker that his has connected to.)

Similarly, you can get a 20Amp adapter for your 30Amp plug and do the same thing. (I own a RV with a 30Amp service.) Once again, you must limit the load. (I can run my HVAC on a 20Amp circuit, but I have to turn everything else in my RV off to keep from tripping the main breaker.)

If you are installing the 50Amp receptacle, you must still use a standard double pole breaker in the electrical panel. And yes, for a 50Amp RV, you will want to install two phase conductors, a neutral, and a grounding conductor. Everything will work just fine. You will have to install the two phase conductors on opposite phases to prevent overloading the neutral conductor.

Conclusion: The only reason RVs do not utilize the 240 volts for any of their loads is because sometimes the RV owner will use an adapter to connect to lower amperage power sources.

 

[guschash]

Go to a RV store they will have what you need. I had the same problem fround solution in the RV store.

 

[Little Bill]

Jeff - It can get confusing, especially if you don't own, or have worked on, RV sites before. Luckly, I have done both.

Large RVs will require a 50Amp connection to operate everything in the unit; however since many campsites might not have the 50Amp service available, all the loads inside the RV are 120V. That way the RV owner can connection his 50Amp plug into a 30Amp receptacle (via the proper adapter) and can still operate the RV unit, just limiting his usage. (For example, many large units have two HVAC systems. The RV owner would be limited to running one HVAC unit at a time, or risk tripping the 30Amp breaker that his has connected to.)

Similarly, you can get a 20Amp adapter for your 30Amp plug and do the same thing. (I own a RV with a 30Amp service.) Once again, you must limit the load. (I can run my HVAC on a 20Amp circuit, but I have to turn everything else in my RV off to keep from tripping the main breaker.)

If you are installing the 50Amp receptacle, you must still use a standard double pole breaker in the electrical panel. And yes, for a 50Amp RV, you will want to install two phase conductors, a neutral, and a grounding conductor. Everything will work just fine. You will have to install the two phase conductors on opposite phases to prevent overloading the neutral conductor.

Conclusion: The only reason RVs do not utilize the 240 volts for any of their loads is because sometimes the RV owner will use an adapter to connect to lower amperage power sources.

Funny, I'm installing a 50A circuit for an RV outlet right away (tomorrow). I did not realize an RV only used 120V. Especially the one I'm running the circuit for as it is a large one with two HVAC units. The owner says he can run either 30A or 50A, so I suppose that means only one HVAC at a time if using only the 30A. I also saw where he was using an adapter cord from the RV to a 20A receptacle on the side of his house.

He wants the 50A outlet, so I suppose he intends on being able to run both HVAC units at the same time.
Just to be clear, I installed a double pole 50A breaker in the panel and ran the wiring to the RV disconnect, then to the RV inlet box. Is this correct?
Someone posted you have to use a single pole breaker and that confused me. So with the double pole breaker, the RV will just pull from each leg as needed, ie; each leg and neutral?
Just want to be sure I'm doing this correct. All I like is making the connections in the panel.

 

[hillbilly1]

Funny, I'm installing a 50A circuit for an RV outlet right away (tomorrow). I did not realize an RV only used 120V. Especially the one I'm running the circuit for as it is a large one with two HVAC units. The owner says he can run either 30A or 50A, so I suppose that means only one HVAC at a time if using only the 30A. I also saw where he was using an adapter cord from the RV to a 20A receptacle on the side of his house.

He wants the 50A outlet, so I suppose he intends on being able to run both HVAC units at the same time.
Just to be clear, I installed a double pole 50A breaker in the panel and ran the wiring to the RV disconnect, then to the RV inlet box. Is this correct?
Someone posted you have to use a single pole breaker and that confused me. So with the double pole breaker, the RV will just pull from each leg as needed, ie; each leg and neutral?
Just want to be sure I'm doing this correct. All I like is making the connections in the panel.

The single pole breaker is for the 30 amp, not the 50 amp, on the 50 you need two hots, a neutral, and a ground. With the 30 amp, you only need one hot, one neutral, and one ground. Many newer RV's have energy management systems that lock out certain loads if it senses only 120 volts is available ( such as being plugged into a 20 or 30 amp receptacle) (using adapters), instead of a 50 amp where 120/240 is available, even though it does not use 240

 

[ElectricianJeff]

Jeff - It can get confusing, especially if you don't own, or have worked on one

I have hooked up probably about 10 without an issue, however last spring I hooked up one up that was older and used that the guy had just bought. It was way out on some land he owned and he was just using it on occasional weekends. I couldn't get inside but it had a 30 amp. 3-prong plug. I connected it to a 240 volt source on a double pull breaker and grounded the frame of the trailer since it was a semi-permanent install.

I got a call from him a few days later saying that the light bulbs were "exploding" when he turned them on. I immediately went back and droped him to 120 volts and I assume everything is ok because I never geard back.

Now I'm gunshy on these installs

 

[480sparky]

He's probably confused with 50 and 30 amp receptacles. There is an RV 30a 120v receptacle that's common, although it doesn't have a NEMA number. Usually sold by the number TTL-30.

 

[renosteinke]

I think what he really wants is a 30-a 120-v RV receptacle.

They look a lot like an old 50-a range plug, but are slightly smaller. It's not a NEMA pattern, but is standard to the RV industry. Your parts house ought to know about them - it's likely the only non-NEMA thing they stock.

 

[kwired]

it's likely the only non-NEMA thing they stock.

I wouldn't say that, I know of lots of non-NEMA items that are common and in stock at supply houses - to begin with anything with IEC rating is not NEMA.

 

[ElectricianJeff]

He's probably confused with 50 and 30 amp receptacles. There is an RV 30a 120v receptacle that's common, although it doesn't have a NEMA number. Usually sold by the number TTL-30.

Thanks for this information. I learned something today thanks to you guys. I took a look at the plug an "assumed" 240 volt, 30 amp without looking any closer. No wonder his bulbs were blowing. Thanks again, Jeff