Can I convert this to a 50 amp RV outlet?

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SargeW

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So I finally got into the new house today, and started researching ways to power the RV on the pad next to the garage. There is an outlet on the wall, but it looks to be a outlet for a welder?  I put a meter on it and each of the "angled" slots showed 122 volts with the black probe in the ground slot. 

But metering the two hot posts the meter reverted to "1".  I opened up the outlet and one leg is black, the other white, and the ground is green.  I know that I need 4 wires, a ground, neutral, and two hot legs for a RV 50 amp plug.  Is it possible to add a wire and make this work? 

The outlets were done by an electrician, and the wiring inside the garage is done in 3/4" EMT.  I haven't tried to check the breaker box to try to identify the size of the breaker yet. 

Any ideas or advice?
 

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John From Detroit

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IS it possible to convert to a 50 amp RV outlet yes two different ways

one way is to run new wire to it, or run a 4th wire to it and do it properly. I have done that in one install.

The other I do not recommend.. But it involves moving the white wire to the white bus at the breaker box. replacing the existing double breaker with a single (or two singles one not connected) and hooking both X and Y terminals on the outlet to the black. I suggest the breaker be no bigger than the smaller of what is in there now or 50 amps.
 

SargeW

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I not sure what size the breaker is now John, but could you elaborate a bit on the "double or single" breaker part?  If it didn't increase my available power, I am not sure it would accomplish the goal.
 

grashley

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My thought would be to simply use the (I assume) 120V 30A power that is already there.  It may require the receptacle be replaced, but nothing more.  Use a 30 --> 50 adapter and you are good to go.  While this will limit power available, 30A should be plenty while at home, unless you are living in it.
 

kdbgoat

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The existing wire in the conduit isn't large enough for 50 amps. You need (3) #6 for two hots and a neutral, along with a #8 ground wire for a true 50 amp circuit. The neutral has to be white, and the ground has to be green. The hots should be one black and one red. You can use colored tape as long as it's wrapped around the visible portion of the wires. That's legal in a 3/4" emt. Then you need a double pole 50 amp breaker. If you look at your power panel, you probably have a double pole breaker for the kitchen range and one for the dryer, assuming they're not gas.
Also don't do the second thing John posted, he didn't recommend it anyway. It's not legal.
 

NY_Dutch

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The part I find disturbing is the 122 volt readings from both the black and white wires to ground. Knowing what size/type breaker it's connected to would help clear that up. As said, the wires are undersized for 50 amp, but could be used for 30 amp service if wired correctly to the correct outlet. Was your meter set to a range high enough to read 240 volts, Marty?
 

xrated

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SargeW said:
So I finally got into the new house today, and started researching ways to power the RV on the pad next to the garage. There is an outlet on the wall, but it looks to be a outlet for a welder?  I put a meter on it and each of the "angled" slots showed 122 volts with the black probe in the ground slot. 

But metering the two hot posts the meter reverted to "1".  I opened up the outlet and one leg is black, the other white, and the ground is green.  I know that I need 4 wires, a ground, neutral, and two hot legs for a RV 50 amp plug.  Is it possible to add a wire and make this work? 

The outlets were done by an electrician, and the wiring inside the garage is done in 3/4" EMT.  I haven't tried to check the breaker box to try to identify the size of the breaker yet. 

Any ideas or advice?

The NEMA 10-30R is normally used as a dryer outlet (240VAC) and if wired correctly should read 120V from one of the angled slots to neutral.  And also 120V from the other angled slot to neutral.  The probes inserted into the both the angled slots should read 240V.  The fact that the you are seeing a "1" when you put both probes on the the angled slots almost leads me to believe that the 10-30R was wired incorrectly and was being used as a "heavy duty 120V receptacle.  See if you can find that wire coming into the breaker panel and verify this for me.
 

NY_Dutch

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xrated said:
The NEMA 10-30R is normally used as a dryer outlet (240VAC) and if wired correctly should read 120V from one of the angled slots to neutral.  And also 120V from the other angled slot to neutral.  The probes inserted into the both the angled slots should read 240V.  The fact that the you are seeing a "1" when you put both probes on the the angled slots almost leads me to believe that the 10-30R was wired incorrectly and was being used as a "heavy duty 120V receptacle.  See if you can find that wire coming into the breaker panel and verify this for me.

Yep, that's what I'm thinking, something isn't right. He should be seeing either 120 across the white and black terminals and only 120 on the black to ground, not the white to ground if it's wired for 120. Or 240 across the white and black as well as 120 to ground from both if it's wired for 240. As said, it would help to know what the breaker setup is in determining what was intended.
 

regval

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If you want to convert the outlet to a Nema 14-50R you can do the following:
Be safe.  Turn off the main breaker to kill power to the panel and carefully remove the panel cover to access the breakers.
I'll assume you've identified the breaker that powers the outlet. My guess it's a double throw 30A breaker (see example photo). Turn it off. Test for voltage at the breaker... Should be zero.
Disconnect the white wire from the breaker and attach it to the neutral buss bar with all the other white wires.
Pull an additional wire (red) through the conduit from the outlet to the breaker panel.
Attach the red wire to the terminal on the breaker where the white wire was connected.
At the receptacle, remove the old recepticle. Refer to wiring diagrams for the 14-50R recepticle. The red and black wires are power (hot), the white is neutral and the green is ground.
If your panel breaker is 30A, then the wire was sized for 30A. Don't upsize to a 50A breaker without running larger wires, it's a fire risk. It's perfectly acceptable to run less current to an outlet rated for more.
You'll have a '50' amp recepticle that you can safely plug your coach into but with limited power (total of 7200 watts) with a 30A breaker. This should be sufficient to run any system but not everything in the coach at the same time.


 

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Rene T

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regval said:
If you want to convert the outlet to a Nema 14-50R you can do the following:
Be safe.  Turn off the main breaker to kill power to the panel and carefully remove the panel cover to access the breakers.
I'll assume you've identified the breaker that powers the outlet. My guess it's a double throw 30A breaker (see example photo). Turn it off. Test for voltage at the breaker... Should be zero.
Disconnect the white wire from the breaker and attach it to the neutral buss bar with all the other white wires.
Pull an additional wire (red) through the conduit from the outlet to the breaker panel.
Attach the red wire to the terminal on the breaker where the white wire was connected.
At the receptacle, remove the old receptacle. Refer to wiring diagrams for the 14-50R receptacle. The red and black wires are power (hot), the white is neutral and the green is ground.
If your panel breaker is 30A, then the wire was sized for 30A. Don't up size to a 50A breaker without running larger wires, it's a fire risk. It's perfectly acceptable to run less current to an outlet rated for more.
You'll have a '50' amp receptacle that you can safely plug your coach into but with limited power (total of 7200 watts) with a 30A breaker. This should be sufficient to run any system but not everything in the coach at the same time.

That sounds a little scary and I'm not a electrician. What happens if he sells the house and the buyer starts looking around and decides to increase the breaker to 50 amp because the receptacle has 4 wires?  I could be that guy because I would have no have no clue as to what size wire I would need to be safe and legal. I think someone has already said this would be a bad idea because the wiring is not big enough to support 50 Amp. Why take the chance IMHO.
 

John From Detroit

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SargeW said:
I not sure what size the breaker is now John, but could you elaborate a bit on the "double or single" breaker part?  If it didn't increase my available power, I am not sure it would accomplish the goal.

240 volt service is two hot leads  Takes a double breaker (Two breakers tied together)  120 volt is one hot. (And the neutral) takes only one breaker not tied to the one next to or across from it.

Take a look at your breaker box and it will be obvious..

The main breaker on your RV is likely a double ganged unit.
 

lynnmor

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Rene T said:
That sounds a little scary and I'm not a electrician. What happens if he sells the house and the buyer starts looking around and decides to increase the breaker to 50 amp because the receptacle has 4 wires?  I could be that guy because I would have no have no clue as to what size wire I would need to be safe and legal. I think someone has already said this would be a bad idea because the wiring is not big enough to support 50 Amp. Why take the chance IMHO.

I think that someone that increases breaker size should take responsibility for his own actions.  The answer from regval was spot on.  Yes, it would be better to pull heavier wires, but if it insn't needed why bother?
 

Gary RV_Wizard

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Yep, that's what I'm thinking, something isn't right. He should be seeing either 120 across the white and black terminals and only 120 on the black to ground, not the white to ground if it's wired for 120. Or 240 across the white and black as well as 120 to ground from both if it's wired for 240.
I also feel this way. The +120 to ground indicates both the slanted pins are hot, yet the wire color suggests they are hot & neutral.  I'm also wondering how to interpret the '1" across the two slanted pins - that is dependent on the meter design. In many meters it indicates no reading, but hot-to-neutral should show +120 and Hot-to-Hot would show zero in many meters (not a 1 or no reading).

Checking the breaker that feeds this circuit is a necessary step. If it is a double pole breaker, it's 240v. If single, it cannot be other than 120v. You can also look to see where the white wire is actually connected, i.e. to a breaker or to the neutral bus. And not the breaker amperage while you are at it.

There can be no valid advice about making this into 50A until the mystery is resolved.  At this point all we can say for sure is that a 4th wire is going to be needed. There is no escaping that.
 

regval

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Rene T said:
That sounds a little scary and I'm not a electrician. What happens if he sells the house and the buyer starts looking around and decides to increase the breaker to 50 amp because the receptacle has 4 wires?  I could be that guy because I would have no have no clue as to what size wire I would need to be safe and legal. I think someone has already said this would be a bad idea because the wiring is not big enough to support 50 Amp. Why take the chance IMHO.
The future holds many, many possibilities, including someone installing an incorrectly sized circuit breaker for a branch circuit. The OP asked the question ?Can I convert this to a 50 amp outlet??
My response answered that question. The legality and risks are generally known by adults attempting to perform work for which they are not knowledgeable or qualified. No need for me to point out the obvious.

 

SpencerPJ

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regval said:
The future holds many, many possibilities, including someone installing an incorrectly sized circuit breaker for a branch circuit. The OP asked the question ?Can I convert this to a 50 amp outlet??
My response answered that question. The legality and risks are generally known by adults attempting to perform work for which they are not knowledgeable or qualified. No need for me to point out the obvious.

I agree SargeW.  You bought a beautiful house.  Spend the couple hundred and get that wired exactly correct.  ;)  It's just more money  ;D ;D
 

SargeW

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NY_Dutch said:
Yep, that's what I'm thinking, something isn't right. He should be seeing either 120 across the white and black terminals and only 120 on the black to ground, not the white to ground if it's wired for 120. Or 240 across the white and black as well as 120 to ground from both if it's wired for 240. As said, it would help to know what the breaker setup is in determining what was intended.

And also as I sit here and think about it, I don't remember if I set the meter on the 200 or 500 volt setting. It was a pretty crazy day, so I could have not switched the meter to the higher setting.  I will recheck when I am back in a few days. 
 
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