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When building our home, I pre-wired for a 50amp electric car outlet using a 6/2 wire (not 6/3 because according to Tesla charging station, they only need 6/2. 6/3 wire was going to cost me $20 more - oh man... ). We bought an RV that accepts 30amp using TT-30P.

The RV came with a 50amp to 30amp converter and I have a 50 amp (14-50R) ready to install.

Can I install a 14-50R knowing that only three wires are going to be used during the conversion to a 30amp TT-30P?

Does the 50amp need to be a wired as 3 pole or wire as a traditional 110v (one hot, the other neutral)?

Thanks for your help!

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    Is switching out the receptacle and breaker for this circuit an option? – ThreePhaseEel Oct 13 '20 at 1:16
  • Yes, after some time, it seems like thats the only option. I changed out the breaker to a single pole 30 amp and changed out the receptacle. Thank you for your help! – Paul M Oct 13 '20 at 1:33
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    Post that as an answer and I'll give you an upvote for it :) – ThreePhaseEel Oct 13 '20 at 1:34
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Sophie's choice: One way, you fry half the appliances in the RV... The other way, you electrify the chassis of the RV. Whoops! The only other possibility with a 6/2 cable is to hook up neutral and ground properly, then not hook up one of the hot wires, but this too is bad (just less destructively).

The only way to support a 14-50 with 6/2 is to add a 12 KVA transformer to the mix.

But why bother? You don't benefit from a 14-50. You benefit from a TT30, which is the plug your RV actually does have.

That's a much simpler matter.

  • Change the 50A 2-pole breaker to a 30A 2-pole* breaker.

  • Move the white wire from the breaker to the neutral bar. Very important!

  • Throw the NEMA 14-50 recep on the shelf. You will not be using it today.

  • Install a TT30 receptacle.

  • Enjoy your RV.

Now, you may find the breaker or recep will not accept a #6 wire. In that case you'll need to pigtail a #10 wire onto it. The big blue wire nuts should suffice. Crank Hard. No... HARD!



* Mind you, you don't actually need a 2-pole breaker, but you do need to fill the empty space, so a 2-pole breaker takes care of that. Also, 30A 1-pole breakers are essentially useless for any purpose but TT30 RV outlets. 30A 2-pole breakers are used for all sorts of things.

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  • Thanks that was it. I replaced the 50amp breaker to a single pole 30 amp. And wired the tt30 plug and there it was. I was hoping to keep it a 50amp so it could be expandable to other applications like a big welding unit (i dont know anything about welding) or other heavy duty appliances. This will work for now and if I need 220v 50amp in future, I will just replace the plug. – Paul M Oct 16 '20 at 22:49

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