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TT-30R to NEMA 14-50 Question

Litre

Member
Sep 3, 2019
22
0
Boise, ID
I just had a house built and purposefully put a NEMA 14-50 outlet where my future Tesla would be parked. This weekend, I finally got my car and after about 30-seconds in it, my wife decided she now wants one. The obvious debacle is now how to charge.

When wiring the garage, we also had installed a TT-30R 30A outlet for an RV. We did this for resale as our house has an RV garage. It would appear that our needs are most likely going to change soon, I was curious how simple/difficult it would be to swap from the TT-30R to another NEMA 14-50. The panel can handle the load, so I'm mostly curious as to whether or not the wiring is similar/interchangeable. Essentially - can I have an electrician swap the outlet and put in the correct 50A breaker and be good, or is the wiring totally different between the two?

Thank you!
 

Rockster

Active Member
Oct 22, 2013
3,010
4,617
McKinney, TX
Why not just put a couple (or more) wall chargers* on a single circuit and let them share the circuit? They're designed to do exactly that. If you had 100 amps to spare, you could share 100 amps across four wall chargers and future proof your setup.


*They're officially called "wall connectors" since the actual charger is in the car, but many still call them wall chargers, or HPWC's.
 
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iluvmacs

Member
Jan 27, 2014
489
810
Madison, WI
Unlikely that they put in wires suitable for 50A, but you can have an electrician verify this. But let's assume not... it would be trivial to switch it to a 30A, 240V outlet (since TT-30 is 30A, 120V). Have them change it to 14-30 (if a neutral wire is available), or 6-30. Tesla sells a 14-30 plug adapter, so this is super easy. If you go with 6-30 you will need to buy (or make) a custom adapter.

Otherwise the question comes to how easy it would be to swap the wire. If the wire is in conduit, it's a pretty easy job. But most houses don't use conduit unless local code requires it. Or if it's Romex wire in unfinished space it could be very easy to replace. Sounds like you really just need a knowledgeable professional to look and tell you, rather than strangers on the Internet, since we can't see your installation :).
 
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KenC

Active Member
Sep 4, 2018
3,629
3,293
Maine
I just had a house built and purposefully put a NEMA 14-50 outlet where my future Tesla would be parked. This weekend, I finally got my car and after about 30-seconds in it, my wife decided she now wants one. The obvious debacle is now how to charge.

When wiring the garage, we also had installed a TT-30R 30A outlet for an RV. We did this for resale as our house has an RV garage. It would appear that our needs are most likely going to change soon, I was curious how simple/difficult it would be to swap from the TT-30R to another NEMA 14-50. The panel can handle the load, so I'm mostly curious as to whether or not the wiring is similar/interchangeable. Essentially - can I have an electrician swap the outlet and put in the correct 50A breaker and be good, or is the wiring totally different between the two?

Thank you!
Obviously just ask the electrician, for what's possible and up to code, but it probably all depends upon the gauge of the wiring. The TT is going to use wiring for a 30amp outlet, while the NEMA 14-50 is using wiring for 50amps, probably 6gauge. I suppose the electrician may be able to wire your outlet for 240v by replacing the receptacle and putting in a double-pole 30amp breaker if the wiring gauge isn't thick enough. Of course, that means you'd be charging at 24amps on the 30amp outlet, and not 32amps on the NEMA 14-50. Not a huge difference. Also, I'm assuming you'd use the Tesla 10-30 adapter or whatever 30amp adapter they sell, and a NEMA 10-30, or 6-30 or 14-30 outlet.
 
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SSonnentag

Rocket Scientist
Apr 11, 2017
1,739
2,188
Arizona
I'd leave the 14-50 and TT-30R for the RVs and welder and have an electrician install a dedicated 100A circuit to two Tesla HPWCs. It's so much nicer to leave the mobile connectors coiled up in the trunk for emergencies and not have to fiddle with outlets, plugs and potentially not having a way to charge via outlet with you in your car because you left the mobile connector at home.
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,437
7,660
Boise, ID
Wire size rating corresponds to the amps it will need to carry, but you can easily change an outlet and breaker to use the same wiring run to convert it from a 120V to a 240V circuit. So, I would recommend to change that TT-30, which is a 120V circuit, over to a 6-30 outlet, which is a 240V outlet type. Tesla is kind of dumb in not selling an official 6-30 plug for their mobile connector, but EVSEAdapters makes really good official looking adapters that are wonderful. They are a little spendy ($85) because they are hand made, but they are excellent quality. So here is their 6-30 adapter:
NEMA 6-30 Adapter for Tesla™ Model S™/X™/3™ Gen 2 – EVSE Adapters
 
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user212_nr

Active Member
Aug 26, 2019
1,407
744
US
I just had a house built and purposefully put a NEMA 14-50 outlet where my future Tesla would be parked. This weekend, I finally got my car and after about 30-seconds in it, my wife decided she now wants one. The obvious debacle is now how to charge.

When wiring the garage, we also had installed a TT-30R 30A outlet for an RV. We did this for resale as our house has an RV garage. It would appear that our needs are most likely going to change soon, I was curious how simple/difficult it would be to swap from the TT-30R to another NEMA 14-50. The panel can handle the load, so I'm mostly curious as to whether or not the wiring is similar/interchangeable. Essentially - can I have an electrician swap the outlet and put in the correct 50A breaker and be good, or is the wiring totally different between the two?

Thank you!

To change from TT-30R to NEMA 6-30 you'd need to repurposed a white wire as a second live wire to get 240v. While it is possible, the electrician probably can't legally do that.

Your cheapest option would be to take the NEMA 14-50 and split that into two 6-20 or 14-20 outlets. Then if that is not sufficient can always get your 14-50 back and install a second one.
 

user212_nr

Active Member
Aug 26, 2019
1,407
744
US
It perfectly legal. You just have to mark each end of the white wire with red or black tape to indicate the re-purpose. No sweat.

I asked the same question in another thread and got that answer... guess it is wrong then.

He probably still does not want to dismantle his RV port.
 
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