Wiring a 50amp RV plug

[sanddan]

A 50 amp RV plug has two separate 25 amp 110V circuits. I have a 50 amp 220V welding plug near where I want the RV plug to be located. Since the welding plug has two,120V hot wires, one neutral wire and one ground can I make up two separate 120V legs from the welding plug? It seems like I should be able to, each 120V leg has a hot, neutral and ground. If I check volts I get 120 across the hot and neutral and 220 across the two hots. Or am I missing something? I will not run the welder and the RV at the same time so I shouldn’t have excessive load issue. I could add a small sub panel to keep the wiring neat and tidy if required.


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[The Cobbler]

are you positive your welder circuit has a neutral? or are you using the ground to get 120

 

[sanddan]

are you positive your welder circuit has a neutral? or are you using the ground to get 120

I’ll double check tomorrow. Been awhile since I last looked.


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[Bert_]

A 50 amp RV plug has two separate 25 amp 110V circuits.

Nope

I have a 50 amp 220V welding plug near where I want the RV plug to be located. Since the welding plug has two,120V hot wires, one neutral wire and one ground can I make up two separate 120V legs from the welding plug? It seems like I should be able to, each 120V leg has a hot, neutral and ground. If I check volts I get 120 across the hot and neutral and 220 across the two hots. Or am I missing something?

Welder plugs don't have a neutral. Unless you're using something non standard.

I will not run the welder and the RV at the same time so I shouldn’t have excessive load issue. I could add a small sub panel to keep the wiring neat and tidy if required.


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I have no problem putting multiple 240v outlets on a circuit.

 

[ddgood]

Most welder outlets are a 6-50R receptacle (250V/50A) which are typically wired with two hot legs and a ground.

Most RV 50A outlets are a 14-50R receptacle (125/250V/50A) which are wired with two hit legs, a neutral and a ground.

If you connect your RV to a 250V circuit without the neutral you will probably damage all of your appliances and your power converter.

Here is a great article that better explains the differences ...

https://www.rvtravel.com/can-i-use-a-welder-outlet-for-50-amp-rv-power/

 

[sanddan]

Most welder outlets are a 6-50R receptacle (250V/50A) which are typically wired with two hot legs and a ground.

Most RV 50A outlets are a 14-50R receptacle (125/250V/50A) which are wired with two hit legs, a neutral and a ground.

If you connect your RV to a 250V circuit without the neutral you will probably damage all of your appliances and your power converter.

Here is a great article that better explains the differences ...

https://www.rvtravel.com/can-i-use-a-welder-outlet-for-50-amp-rv-power/

I wouldn’t


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[Bert_]

I have actually wired a welder outlet and a RV outlet together once. But I ran the right wire, 6-3 NM, so I had a neutral for the rv outlet.

Welder outlet was inside the garage, RV outlet was right on the other side of the wall outside.

 

[mrjaw14]

Is your RV 120v or 240V? Does it have a 3 blade 30a plug or a 4 blade 50a plug? 50a RVs use the input as two 120 circuits but can also provide 240v for special appliances in nicer RVs. So a 240v RV actually splits that 240v circuit into two 120v circuits in a lot of cases. But the wiring is sized for the consideration below.

The thing to consider with splitting any 240 circuit into two 120 circuits is that the neutral has to be sized to handle the amperage. On a 240 appliance the current is passed between the two hots and the neutral handles any imbalance. With 120 the current is between hot and neutral. So current on neutral is higher with two 120 circuits than the same 240v circuit used as 240. It’s all in the use case, just design accordingly.

 

[Bert_]

Is your RV 120v or 240V? Does it have a 3 blade 30a plug or a 4 blade 50a plug? 50a RVs use the input as two 120 circuits but can also provide 240v for special appliances in nicer RVs. So a 240v RV actually splits that 240v circuit into two 120v circuits in a lot of cases. But the wiring is sized for the consideration below.

The thing to consider with splitting any 240 circuit into two 120 circuits is that the neutral has to be sized to handle the amperage. On a 240 appliance the current is passed between the two hots and the neutral handles any imbalance. With 120 the current is between hot and neutral. So current on neutral is higher with two 120 circuits than the same 240v circuit used as 240. It’s all in the use case, just design accordingly.

Close but since each 120v line is 180* out of phase the neutral currents cancel.

Example,
One line draws 20A and the other draws 12A. The neutral current would be 8A.

 

[mrjaw14]

Close but since each 120v line is 180* out of phase the neutral currents cancel.

Example,
One line draws 20A and the other draws 12A. The neutral current would be 8A.

That’s what I meant by handling the imbalance, but perhaps I over simplified it. thanks for providing additional clarification!

 

[dcg9381]

IWith 120 the current is between hot and neutral. So current on neutral is higher with two 120 circuits than the same 240v circuit used as 240. It’s all in the use case, just design accordingly. .

That's what I thought too, before I considered that there is a "phase" to power. These residential systems are single phase, with the hot legs being 180 degrees out of phase with each other. The load on the neutral is fine as long as the hots are out of phase.


I used 50A RV connections for my welder all the time... They are my "go to" for 240V outlets.

A big RV will do just fine on a 50A RV connector that's only got 240V @ 30A of available breaker behind it - for the reasons listed above - RVs really are doing 120V x 2, not 240V.... A 50A RV "outlet" really has almost 4 times the available power of a 30A RV "outlet" (total watts).

 

[AntonLargiader]

I don't think of the 14-50 as an RV connector specifically. It's just a 50A 4-wire connector, common for EVSE, ovens, RVs, and more. Plenty of these devices do not and cannot draw anywhere near 50A.