110volt RV Hook-up from 3 wire 220Volt

[RDeMeyer]

I need to add a 110-120 volt 30 Amp outlet for an RV. I have a seldom used 3 wire 220v circuit that I would like to tap to get the 110v. I know if this was a 4 wire 220v I could easily grab one side of the hot legs and make a 100v for this but since I only have a 3 wire circuit I need do something else.

Running another wire back to the box isn't a practical solution as all the walls have foam insulation. Does anybody have any experience and or recommendation for a step down transformer that could be used instead?

Thank you!

Randy

 

[wyliesdiesels]

Your voltages are all over the place.

Its 120/240v

Not 100 110 or 220.

Does the circuit have a neutral? Doesnt sound like it since its 3-wire 240v

What type of wire is it and what is the gauge?

 

[Norcal]

Your voltages are all over the place.

Its 120/240v

Not 100 110 or 220.

Does the circuit have a neutral? Doesnt sound like it since its 3-wire 240v

What type of wire is it and what is the gauge?

It sounds like it could be a 3-wire dryer receptacle but the OP is the only one who can clarify that.

 

[alfredeneuman]

Is your circuit in a cable, or is it in conduit?

 

[Slowgsr]

Sounds like you need to move the white wire from the breaker to the neutral bar. Replace the breaker and the receptacle

 

[alfredeneuman]

What if there is no white wire?
That's the reason why I asked him if it was in cable or conduit.

 

[walta]

The first question is what plug is on the RV and does it need 240 volts?

This chart may be helpful.

https://www.rxms.com/files/downloads/documents/Bryant_Chart.pdf

If the RV needs 5-30 I see no reason you could not replace the breaker and rewire the circuit.

If the RV needs 14-30 the only safe and code compliant way would 3 conductors and a separate ground wire that it sounds like you do not have.

Walta

 

[checkthisout]

Sounds like you need to move the white wire from the breaker to the neutral bar. Replace the breaker and the receptacle

And it's just that simple.

Leave ground ground.

Move the wire of your choice off the 240V breaker onto the neutral and presto, you have a whatever amp circuit @ 120 Volts

Replace plug with RV style plug.

Done.

 

[mm08822]

Sounds like you need to move the white wire from the breaker to the neutral bar. Replace the breaker and the receptacle

Only if conductors are #10 or larger.

If smaller, he would need to go the xformer route.


OP, As others have asked – what are the current details:
CB size
Wire size
Conductor count in cable
Assumption is you have cable and not conduit
Distance to panel
Is the full 30A @120vac required?
You are certain you will no longer need 240vac at current location?
What type of receptacle is currently installed? (NEMA size)

 

[checkthisout]

I ran my rv off a 20 amp circuit for a few years.

If the wire size is an issue, just breaker the circuit at 20 amps.

That's plenty.

They make those adapters for rv plugs so it will plug into a standard outlet. I bet you would never need more than the 20 amp circuit.

 

[slow]

I ran my rv off a 20 amp circuit for a few years.

If the wire size is an issue, just breaker the circuit at 20 amps.

That's plenty.

They make those adapters for rv plugs so it will plug into a standard outlet. I bet you would never need more than the 20 amp circuit.

agreed unless your running an air conditioner unit.

 

[checkthisout]

agreed unless your running an air conditioner unit.

I was. I think the a/c only drew like 1200 watts. Higher start up of course but not enough to pop breaker.

 

[alfredeneuman]

We really need the OP to provide some additional input.
(otherwise it's just speculation and guessing at this point)
He hasn't posted since his original question.

 

[Slowgsr]

Only if conductors are #10 or larger.

If smaller, he would need to go the xformer route.


OP, As others have asked – what are the current details:
CB size
Wire size
Conductor count in cable
Assumption is you have cable and not conduit
Distance to panel
Is the full 30A @120vac required?
You are certain you will no longer need 240vac at current location?
What type of receptacle is currently installed? (NEMA size)

why would it matter what size the wire is?

#12 can go up to 20a
#10 can go up to 30a
#14 can only go on 15a

 

[mm08822]

why would it matter what size the wire is?

#12 can go up to 20a
#10 can go up to 30a
#14 can only go on 15a

Why does it matter? You answered your own q.
OP’s original request is 30A @120vac. #14, and #12 cannot support 30A.

The only way #14 or 12 can deliver full 30A @120vac is to use a transformer with 240vac input and step down to 120vac on the output.

The bigger q is does the OP really need 30A.