50 Amp RV Outlet vs. 50 Amp Welding Outlet

[Scsmith42]

Wow! This thread is a prime example of why folks who don't know exactly what they're talking about should refrain from giving out advice. Two pages of assumptions and confusion.



Bottom line:

A 50A RV circuit is a 120/240V, 4-wire circuit. It's not "120", and it's NOT "240". It's 120/240V, using two hots, a neutral and a ground.



A welder is typically a straight 240V circuit. Two hots and a ground.





YES, you are correct. You can use your welder on your RV circuit using that exact adapter. You can also just replace the plug with a 14-50P plug and ignore the neutral prong.

Amen....


Scott

 

[ishiboo]

The RV plugs I have seen have both the hots off the same buss bar on the panel, hence the 120 volt and 120 volt supply. Nothing in the RV is supposed to be 240 volt and they did not want 240 volt to the plug and to the RV that you would get from a L1, L2 way that you conventionally wire a 4 wire outlet. This was the custom on the 30 am RV plugs and continued to the 50 from what I saw at a neighbors RV wiring he had put in.

That's interesting. One of the big benefits of 240v is you get twice the amperage at 120v. If what you were saying was true, a 50A service cord would need to have a neutral to be sized for 100A, because the neutral needs to be capable of carrying both 50A hot loads. With 240v, the neutral would only carry the imbalance between the two.

I've never seen a cord with an upsized neutral like that, have you?

50A RV service is standard 4-wire, 120/240. As many have said. 30A service is 120v.

(For some reason some genius decided on 50A, 120v service for boats as an "upgrade" over the 30A 120v service. So some boats/marinas are/were configured like this. It is replaced with the same 50A 120/240 service as an RV.)

 

[alpinewhite]

I've never heard of an RV that runs 240VAC appliances. They do, however, use two legs of a 240VAC connection to increase the total power. Remember that these RVs are also allowed to plug into a 30-amp 120VAC circuit but with limited usage since it's a lower amperage outlet.

 

[Rock knocker]

The RV plugs I have seen have both the hots off the same buss bar on the panel, hence the 120 volt and 120 volt supply. Nothing in the RV is supposed to be 240 volt and they did not want 240 volt to the plug and to the RV that you would get from a L1, L2 way that you conventionally wire a 4 wire outlet. This was the custom on the 30 am RV plugs and continued to the 50 from what I saw at a neighbors RV wiring he had put in.

I have no idea what you're trying to claim? That RV plugs get double the current by running two parallel hots off the same pole? That would double the load on the neutral, and melt the cable.

 

[wyliesdiesels]

That's interesting. One of the big benefits of 240v is you get twice the amperage at 120v. If what you were saying was true, a 50A service cord would need to have a neutral to be sized for 100A, because the neutral needs to be capable of carrying both 50A hot loads. With 240v, the neutral would only carry the imbalance between the two.

I've never seen a cord with an upsized neutral like that, have you?

50A RV service is standard 4-wire, 120/240. As many have said. 30A service is 120v.

(For some reason some genius decided on 50A, 120v service for boats as an "upgrade" over the 30A 120v service. So some boats/marinas are/were configured like this. It is replaced with the same 50A 120/240 service as an RV.)

I have no idea what you're trying to claim? That RV plugs get double the current by running two parallel hots off the same pole? That would double the load on the neutral, and melt the cable.

Just the reason why my BS meter pegged in #27!!

 

[ishiboo]

I think the confusion is that the 30A->50A adapters do this where 120/240 is not available. But then you're limited to 30A total on two 50A conductors.

IF there were 240v appliances and an adapter was used, those appliances would simply see 0V and not do anything.

 

[Charles (in GA)]

The rv with 50 amp connectors is nothing more than a multi wire branch circuit.(MWBC) supplied by the 14-50 plug.

You can buy ready made adapters to step down to TT30 for a smaller RV. Of course the 50 amp breaker won't protect the circuit after the adapter, but its commonly done.

www.myrv.us/electric/pg/50amp_service.htm

 

[ishiboo]

The rv with 50 amp connectors is nothing more than a multi wire branch circuit.(MWBC) supplied by the 14-50 plug.

You can buy ready made adapters to step down to TT30 for a smaller RV. Of course the 50 amp breaker won't protect the circuit after the adapter, but its commonly done.

www.myrv.us/electric/pg/50amp_service.htm

Not really a branch circuit. I'd call it what it is - a 120/240 service. Just as the 120/240 that comes into your house is a service, not a MWBC, despite the fact it also has (those same) two 120v legs sharing a neutral. Reaches the RV, hits the main panel and branch circuits leave from there. A MWBC is a simple concept given a fancy name so we can write that the laws of God say Thou Shall Use a Handle-Tied Breaker.

 

[wyliesdiesels]

Not really a branch circuit. I'd call it what it is - a 120/240 service. Just as the 120/240 that comes into your house is a service, not a MWBC, despite the fact it also has (those same) two 120v legs sharing a neutral. Reaches the RV, hits the main panel and branch circuits leave from there. A MWBC is a simple concept given a fancy name so we can write that the laws of God say Thou Shall Use a Handle-Tied Breaker.

Huh? 2 hots (or 3 if 3-phase wye) sharing a neutral IS a MWBC....not sure what youre talking about...

 

[Charles (in GA)]

Huh? 2 hots (or 3 if 3-phase wye) sharing a neutral IS a MWBC....not sure what youre talking about...

If ishiboo wants to call it something else, he can, but its function in the RV is exactly the same as a MWBC. Two opposing hots sharing a neutral. Just like many people have done in houses, shops and kitchens. Indeed, they break it down further in the RV with breaker panels protecting the circuits branched off each side. But from the inlet fitting to the RV breakers its nothing more than a mobile MWBC.

The link in included above is a good clear explanation of the RV circuit and what it is.

Charles

 

[Rock knocker]

Some people just shouldn't post on some forums. And I know a couple right here on this thread

 

[wyliesdiesels]

Some people just shouldn't post on some forums. And I know a couple right here on this thread

Not stating any names huh?

 

[Rock knocker]

Just a hint, none of the names start with Speedy, Chuck or Wylie

 

[whitecharger2014]

Why not install both outlets?

 

[wyliesdiesels]

Just a hint, none of the names start with Speedy, Chuck or Wylie

U forgot charles, Norcal, pattenp, aceman

 

[Rock knocker]

U forgot charles, Norcal, pattenp, aceman

Norcal?

All the loads on a RV w/ a 50A plug are 120 volts, a 50A to 30A adapter just jumpers both hot legs in order run things, just can't run everything.

As said by others, just make a adapter.

 

[wyliesdiesels]

Whats the question?

He is an electrician if thats what your wondering...

 

[Rock knocker]

Just not a writer?

 

[Rock knocker]

Whats the question?

He is an electrician if thats what your wondering...

He isn't making sense right there. Maybe he's just not a writer.

 

[theoldwizard1]

Just a hint, none of the names start with Speedy, Chuck or Wylie

U forgot charles, Norcal, pattenp, aceman

My son's neighbor's company is "Sparky Joe".

 

[theoldwizard1]

If it was me (not an electrician), I would install a 14-50R receptacle and change the plug on the welder, assuming that the plug on the welder is NOT a molded assembly. Even if the plug on the welder is molded, it might be cheaper to buy a 14-50P and a length of cordage (8/4, 6/4 ?) than those overpriced adapters.

Or buy a 50a 4-wire "range cord" - Amazon $28

This is also a case where installing BOTH receptacle makes sense, even though code does not allow it. (I don't understand why. The 50A breaker protects the wire.)

 

[Creative Fab]

Or you could do this and be able to have several options. Except run the welder as these are all 120 outlets that are needed.
http://www.pplmotorhomes.com/parts/rv-power-cords/rv-cheater-box.htm

I have one the adapters which works great, most places, exception being our MI state parks which are all wired with GFI's. This adapter will not work with a GFI.

 

[sberry]

I found one the other day that must have been a flea mkt invention. I think it is a 30 to 15 adapter if I looked at it right. I looked for some writing on it, none.

 

[ishiboo]

Huh? 2 hots (or 3 if 3-phase wye) sharing a neutral IS a MWBC....not sure what youre talking about...

So it's a MWBC when it comes in to your house?

There is a definition of a branch circuit. Do you know what it is? A service is not a branch circuit, for example.

 

[ishiboo]

The distinction between a branch circuit and a feeder can be a source of confusion for many Code users. The first step in eliminating this confusion is to understand that the NEC defines a branch circuit as “the conductors between the branch circuit final overcurrent device protecting the circuit and the outlets” (such as receptacles or lights) [Art. 100], as shown in Fig. 1. By contrast, a feeder circuit runs from the service equipment, the source of a separately derived system, or other power supply to (rather than from) the final branch circuit overcurrent device.

Does that help?

 

[wyliesdiesels]

So it's a MWBC when it comes in to your house?

There is a definition of a branch circuit. Do you know what it is? A service is not a branch circuit, for example.

The distinction between a branch circuit and a feeder can be a source of confusion for many Code users. The first step in eliminating this confusion is to understand that the NEC defines a branch circuit as “the conductors between the branch circuit final overcurrent device protecting the circuit and the outlets” (such as receptacles or lights) [Art. 100], as shown in Fig. 1. By contrast, a feeder circuit runs from the service equipment, the source of a separately derived system, or other power supply to (rather than from) the final branch circuit overcurrent device.

Does that help?

Huh? We were talking about the branch circuit that feeds an RV. U said that its NOT a MWBC. By the definition u just posted, it is.

And if u look at a service going to a house from the PoCos standpoint, it IS a MWBC....

 

[ishiboo]

Huh? We were talking about the branch circuit that feeds an RV. U said that its NOT a MWBC. By the definition u just posted, it is.

And if u look at a service going to a house from the PoCos standpoint, it IS a MWBC....

You must have reading comprehension issues.

Is the breaker that feeds the RV outlet the final overcurrent device? No, so it's not a branch circuit. There is a sub-panel in the RV, your house has a main panel, etc. Same is true for the PoCo feed.

So, it fails the test of being a branch circuit at all. And thus fails being a multi wire branch circuit.

 

[Creative Fab]

Now we are splitting hairs. Or wires as the case may be lol

 

[Rock knocker]

You must have reading comprehension issues.

Is the breaker that feeds the RV outlet the final overcurrent device? No, so it's not a branch circuit. There is a sub-panel in the RV, your house has a main panel, etc. Same is true for the PoCo feed.

So, it fails the test of being a branch circuit at all. And thus fails being a multi wire branch circuit.

Actually it just feeds a 50A receptacle. You make the choice to plug in an RV with its panel. It could just as well be a compressor or welding machine. So it is not a feeder, but is in fact a MWBC.

 

[C96]

You must have reading comprehension issues.

 

[wyliesdiesels]

LMAO

You must have reading comprehension issues.

Is the breaker that feeds the RV outlet the final overcurrent device? No, so it's not a branch circuit. There is a sub-panel in the RV, your house has a main panel, etc. Same is true for the PoCo feed.

So, it fails the test of being a branch circuit at all. And thus fails being a multi wire branch circuit.

So if its not a branch circuit then what is it?

 

[Rock knocker]

So if its not a branch circuit then what is?

At this point? A delusion of Ishboo's?

 

[wyliesdiesels]

 

[revamped]

Thanks guys for keeping this thread alive... So reading through most of the ******** arguing in the above link, I see that the RV is 120V but pulls off of each leg of the 240 at the panel in the RV. So, I plan to install the 14-50 on a 50A 2-pole breaker and get a 14-50 to L6-30 adapter for my small RV (haven't bought the 5th wheel yet) and a 14-50 to 6-50 adapter to use my welders (I use 3 different ones) off that same 240 outlet since it is between my bays and will be used for work near the front doors.

I have 5 240 drops in the shop right now so I don't want to add more on my 90 amp branch circuit coming off the house.

You guys ROCK!!! I will post pics of my electrical install in my home thread for the garage build... I really went overboard on circuits and outlets!

 

[Radix2]

Bottom line - it would be foolish to not run a neutral conductor on a new build.

If you have it, you can use either 6- or 14- receptacles

Another use for the 14-30-50 3 conductor receptical is for charging EVs

 

[sberry]

Convert one for welders.

 

[wyliesdiesels]

Thanks guys for keeping this thread alive... So reading through most of the ******** arguing in the above link, I see that the RV is 120V but pulls off of each leg of the 240 at the panel in the RV. So, I plan to install the 14-50 on a 50A 2-pole breaker and get a 14-50 to L6-30 adapter for my small RV (haven't bought the 5th wheel yet) and a 14-50 to 6-50 adapter to use my welders (I use 3 different ones) off that same 240 outlet since it is between my bays and will be used for work near the front doors.

I have 5 240 drops in the shop right now so I don't want to add more on my 90 amp branch circuit coming off the house.

You guys ROCK!!! I will post pics of my electrical install in my home thread for the garage build... I really went overboard on circuits and outlets!

Lol.

Last comment is almost 2 yrs old...

Did u mean L14-30??? An L6-30 has no neutral and your RV surely needs a neutral for all 120v equipment.

 

[bczygan]

20 minutes I'll never get back, but very entertaining.

Had to go to the end to find out how everything turned out.

I would have run separate circuits to exactly where they were needed. Cheaper than cable assemblies.

 

[Speedy Petey]

Did u mean L14-30??? An L6-30 has no neutral and your RV surely needs a neutral for all 120v equipment.

I HOPE he means TT30.

 

[wyliesdiesels]

I HOPE he means TT30.

Good catch.

Forgot about the special outlet for RVs.