50A RV OUTLET

[jap]

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.

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/]

The Last sentence of this makes me believe that the 120/208v 1ph service to the 50a 120/240v RV outlet would be permissable.
Is this only in the Handbook?

 

[GeorgeB]

If that was the case they would unknowingly be running the 240v rated equipment on 208v not 240v.

What about the many apartment complexes with 120/208? I've not seen any residential equipment, water heaters, stoves, dryers, heat pumps, furnaces, etc that are not rated for use on both. The heat output will be lower (by 25%) however.

Although 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.

I'd follow the practice of giving them both a 30A and 50A as I usually see. Just be sure to NOT use one phase significantly more than the others. Having multiples of 3 sites on a transformer or feeder breaker makes logical balancing easier.

 

[Electron_Sam78]

We have a couple loops (about 50 RV sites) all wired with 120/208. Been that way for 30 years and no problems. All of our pedestals have one 250V 50a receptacle, one 120V 30a receptacle, and one 120V 20a receptacle under the hood. That's the way I'd go if I were putting one in.

 

[Electron_Sam78]

This is the configuration we use in our pedestals:


View attachment MW pedestal.bmp

 

[jap]

I agree there should never be an issue, but if one should arise it would be nice to have a code statement to back up supplying a 120/240v RV Receptacle with 120/208v.

As long as there's a chance of having 240v equipment in an RV, there will always be a chance of the owner indicating something went wrong with his equipment as a result of having the incorrect voltage available at the outlet.

It seems the code statement indicated in the previous post allows it.
I'm just trying to determine for a fact that this is so.

 

[RUWired]

Is this only in the Handbook?

Yes, and i picked that out of the 2008 CD version.

 

[kwired]

Most of us would supply the same type receptacle with 120/208 for an electric range, and not give it a second thought. Yet the receptacle rating is 120/240.

 

[Cow]

Most of us would supply the same type receptacle with 120/208 for an electric range, and not give it a second thought. Yet the receptacle rating is 120/240.

I agree. I would do the same thing for this RV and never think twice about it.

 

[jap]

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.

I agree with twoskinsoneman.
but it seems that the code statement that RUWIRED posted from the handbook allowes it.

I was just surprised that this statement was only in the handbook.

An Rv is different than an apartment complex where there may be 240v equipment running on 208v power.

The tennant is not the owner of the equipmnet. The Owner can choose to run his 240v equipment on 208v and the tennant could care less (He dont own it).

On an RV the owner does own the 240v rated equipment and if something were to go wrong with the 240v equipment (wether voltage related or not) he could possibly blame it on the incorrect voltage available at the receptacle and turn it back on the installer.

That's why a direct code statement to back up installing 120/208 on a 120/240v rated receptacle on an rv is so important and it seems there is one that allows it.

 

[Twoskinsoneman]

I agree with twoskinsoneman.
but it seems that the code statement that RUWIRED posted from the handbook allowes it.

It does not. Go read the whole section. 551.42, 551.44 specifically refer to RV on-board equipment. It does not specifically allow you run 208 to a 240v receptacle.

Doing so for a receptacle to feed RVs could be bad news and unprofessional. When you plug into a certain configuration receptacle you expect to get that voltage.

When I worked for a mobile communication vehicle manufacturer (TV trucks, Police Mobile Command Units...etc) we would give them the input for shore power they wanted, and would also provide adapters to connect to other receptacles that could be use that may be available.

 

[jap]

So the guys that say they installed it in thier loop and at thier churches and Moose Lodges are all code violations?

 

[jap]

All I'm trying to find out is if this would be a code violation or not and no one,
Including me, seems to be able to determine if it is or not.

 

[Twoskinsoneman]

All I'm trying to find out is if this would be a code violation or not and no one,
Including me, seems to be able to determine if it is or not.

IMHO hooking up a different voltage than that for which the receptacle is rated for would be a 110.3(B) violation.

If someone were hooking 120v to a 277v receptacle I'm sure everyone would have a problem with it. This is the same IMHO.

 

[jap]

I agree with you.

With that being the case it would be a code violation to install a 120/240v RV outlet and feed it with 120/208v.

You would have to either install a 30a 120v RV outlet and forget about letting them use the 2nd air conditioner or any 240v loads they might have in the coach.

or

you would have to install a 208x 120/240v xfmr to get the voltage to 120/240v. at the outlet.

The only way not to second guess my installation in this instance is to install the 30a 120v RV Receptacle or go with a transformer.

 

[Little Bill]

I don't see what the problem is. You said in the OP there were only 120V loads. Whether it is 240/120 or 208/120 the 120V is the same. I've used 208V for 240V rated equipment for years with no problems at all.

 

[jap]

This particular coach does not have 240v loads but there are some out there that do. This Receptacle is being installed to feed Whatever 120/240v coach that may show up. They may have a diffferent one next year.

The problem is saying " Woked for years never had a problem" probably wouldnt carry much weight if something were to happen to the owners 240v equipment.

The only thing to fall back on would be a code statement that specifically allows it.

Without that,,, the only safe play would be to install the 30a 120v outlet unless someone wanted to spring for the 208x 120/240v transformer at this point.

 

[zbang]

I know it's not positive confirmation, but I've had these installed in multiple jurisdictions in multiple states, properly permitted and inspected, and no one has batted an eye at supplying the receptacle with 120/208.

How about this, can you supply an L6-30 with 208v? Most people do. Is it wrong?

"Supply connections are intended to be two-pole, three wire hot-hot-ground circuit with nominal supply voltage of 240 V or 208 V depending on phase configuration."

I'll check the NEMA later today.

 

[Electron_Sam78]

IMHO hooking up a different voltage than that for which the receptacle is rated for would be a 110.3(B) violation.

If someone were hooking 120v to a 277v receptacle I'm sure everyone would have a problem with it. This is the same IMHO.

It would be a violation to hook up 277V to a receptacle rated at only 240V. A receptacle rated at 240V is the maximum rated nominal voltage that can be installed to that receptacle. With a 10% +/- tollerance a 208V supply could have an actual reading of 228V and a 240V system could be as low as 216V. Many appliances are rated a 230 volts to allow for this tolerance.

If someone were hooking 120V to a specially ordered receptacle rated high enough for 277V then there's a completely different problem somewhere

I run 120 volts through wire rated for 600V! Uh oh!:lol:

 

[jap]

That's getting way off base.

I've heard everything but a code statement that would allow 120/208v to be terminated on a 120/240v RV Recptacle.

I would prefer to install the 50a 120/208v outlet, but havent heard of a code statement yet that would allow this type of installation and in the back of my mind I questioned it myself. Thats why I posted the question.

 

[jap]

As far as the L6-30, that could go both ways.

Say you had a piece of equipment come in that had an l6-30 Male end but the machine was strictly 208v and not rated for 208/240v. Would you plug that into a receptacle that was fed 240v?

I wouldnt.

On an RV you dont have the Dual 208/240v Rating that I know of.

The closest thing I've seen was that statement from RUWIRED.