50A RV OUTLET

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J

jap

Senior Member
Occupation
Electrician
i have a situation where the customer is wanting to pull a motorhome into the parking lot next to a church once a year for an annual event. The motor home is set up to run on a 50a 125/250v service. It has 2 air conditioners but does not have any 240v loads inside. All are 120v devices including the air conditioners.

The Service at the church is 208/120 3ph 4w.

Has anyone ever installed a 50a RV outlet on a 120/208v Circuit?
I'm not sure that's even allowed.

They want to be able to run both 120v Air Conditioners. I dont think I can use a Buck Boost transformer to get the voltage to 240v since it most likely will boost the 120v also. If i install a 208 to 120/240v standard transformer it gets really pricy really quick.

I was curious if anyone has run into installing a 50a 125/250v Rv Outlet where there was only a 208/120v service available.

My other option is to install a 30a 120v Rv Outlet and tell them to forget about being able to use the 2nd air conditioner, but i'm sure they'll want to use both.
 
Twoskinsoneman

Twoskinsoneman

Senior Member
Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
jap said:
i have a situation where the customer is wanting to pull a motorhome into the parking lot next to a church once a year for an annual event. The motor home is set up to run on a 50a 125/250v service. It has 2 air conditioners but does not have any 240v loads inside. All are 120v devices including the air conditioners.

The Service at the church is 208/120 3ph 4w.

Has anyone ever installed a 50a RV outlet on a 120/208v Circuit?
I'm not sure that's even allowed.

They want to be able to run both 120v Air Conditioners. I dont think I can use a Buck Boost transformer to get the voltage to 240v since it most likely will boost the 120v also. If i install a 208 to 120/240v standard transformer it gets really pricy really quick.

I was curious if anyone has run into installing a 50a 125/250v Rv Outlet where there was only a 208/120v service available.

My other option is to install a 30a 120v Rv Outlet and tell them to forget about being able to use the 2nd air conditioner, but i'm sure they'll want to use both.
Click to expand...

I agree that if there are no 240V loads don't worry about any of that stuff, it will work great.
 
R

rich000

Senior Member
Can you do it? Yes. For that particular installation.

However, FYI, there are RV's out there with 240V loads. Some have electric stoves and dryers. While the majority of them are 120V, there are exceptions.

I would install a placard or note saying how it is fed.
 
J

jap

Senior Member
Occupation
Electrician
rich000 said:
Can you do it? Yes. For that particular installation.

However, FYI, there are RV's out there with 240V loads. Some have electric stoves and dryers. While the majority of them are 120V, there are exceptions.

I would install a placard or note saying how it is fed.
Click to expand...



Its funny you mentioned that. I just had a sticker made at the print shop that says

120/208v 1ph
Not intended for 240v Loads.

They may not understand it but I feel better about having it there.

Thanks for all the responses.

JAP.
 
Twoskinsoneman

Twoskinsoneman

Senior Member
Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
jap said:
Its funny you mentioned that. I just had a sticker made at the print shop that says

120/208v 1ph
Not intended for 240v Loads.

They may not understand it but I feel better about having it there.

Thanks for all the responses.

JAP.
Click to expand...

I just wanted to be clear, I thought all along you would be installing a 120/208 receptacle, now it sounds like you are going to be installing a 125/250v receptacle with a placard. I disagree with this install. Clearly you should not install a receptacle of a certain voltage configuration that is different from the voltage you will be feeding that receptacle with.
 
R

RUWired

Senior Member
Location
Pa.
It would appear that article 551.44(D) and 551.42(D) would allow both voltage ratings.

551.44 Power-Supply Assembly.
(D) Fifty-Ampere Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(D) shall use a listed 50-ampere, 120/208?240-volt main power-supply assembly.

(D) More Than Five Circuits Without a Listed Energy Management System. A 50-ampere, 120/208?240-volt power-supply assembly and a minimum 50-ampere-rated distribution panelboard shall be used where six or more circuits are employed. The load distribution shall ensure a reasonable current balance between phases.

handbook said:
Experience and field data indicate that supply calculations are not necessary; in some cases, such calculations have resulted in oversized power supplies. In recreational vehicles with six or more circuits, the power supply assembly must have a minimum rating of 50 amperes. Reasonable balancing of the electrical load between phases is required. This section was revised for the 2008 Code to require the panelboard to be rated 120/208-240 to allow connection to a 120/240 single-phase service or a 120/208 3-phase distribution.[quote/]
Click to expand...
 
J

jap

Senior Member
Occupation
Electrician
The Rv's come with a 50a 125/250v Male End and the Midwest UO54 Rv Outlets are 50a 125/250v. That's my delima. Although the Panel in the coach and the power supply cord to it are rated at 250v,I dont have that voltage available,only 208v.
It is possible that they could get a different coach that could possibly could have 240v pieces of equipment in the future.
If that was the case they would unknowingly be running the 240v rated equipment on 208v not 240v.

You can run the larger coaches on a 30a 120v outlet but you loose 1 of the air conditioners. The Air Conditioners are on opposite phases set up for the 50a Feed.
Although all the loads in the coaches are normally 120v, I cant decide wether to put in a 30a 125v outlet or the 50a 120/208v outlet.
Althought the 120/208v outlet would let them run everything they need,
If I cant get a clear answer I'll be leaning towards the 30a 125v outlet.
 
kwired

kwired

Electron manager
Location
NE Nebraska
From what I recall seeing in the past if you use a 50 - 30 amp adapter to plug into a 30 amp receptacle everything will work. But if you use both air conditioners you will overload the 30 amp breaker.

If there is any 240 volt loads they are likely heating elements and if conected to 208 will just take a little longer to deliver the same amount of heat.
 
J

jap

Senior Member
Occupation
Electrician
I'm going to find out for sure. I always thought they were on different phase and (1) wouldnt have power to it when hooked up to the 30a 125v (I may be wrong).

I'm just trying to get a definite answer on the 120/208v install, if its ok or not.
 
pfalcon

pfalcon

Senior Member
Location
Indiana
I've just gone back to do some basic checking on RV power.
That RV should either have 120/240 50a or 120 30a.
125/250 is not used for RVs.

http://www.myrv.us/electric/

As I stated before, most of the 50a RVs that park with us also have a secondary connection to use 30a. A concession necessary because not all RV parks have 50a outlets.
 
J

jap

Senior Member
Occupation
Electrician
125/250V is the Nema Rating on the 14-50r Receptacle.
Theres not an issue with the voltage rating of anything.
Just trying to verify if there is an issue with putting 120/208 on an RV outlet that is most generally 120/240v.
 
J

jap

Senior Member
Occupation
Electrician
I do a lot of camping also. I own a fifth wheel myself and have all the adapters also.
But campsites are wired with 120/240v single phase feeders, not
120/208v 3ph.
 
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