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Converting existing 14-50 NEMA into a HPWC?

Dedmo

Member
Mar 13, 2018
14
7
N. C.
Model X being delivered end of march. Wife already had Model S and referred me so should eventually we should receive the “award Wall charger”. We are just now finishing up the addition of a garage and will have a 14-50 NEMA installed which would be adequate but since we are getting a free WC anyway I’m trying to find out if the outlet can later be converted to the wall charger. I’ve seen posts and videos about adding a range cord to adapt the HPWC to plug into the 14-50 outlet but can’t find anything about the doing the reverse.
 

mongo

Well-Known Member
May 3, 2017
14,002
45,563
Michigan
Model X being delivered end of march. Wife already had Model S and referred me so should eventually we should receive the “award Wall charger”. We are just now finishing up the addition of a garage and will have a 14-50 NEMA installed which would be adequate but since we are getting a free WC anyway I’m trying to find out if the outlet can later be converted to the wall charger. I’ve seen posts and videos about adding a range cord to adapt the HPWC to plug into the 14-50 outlet but can’t find anything about the doing the reverse.

Sure. Exact details depend on your installation. Basically, the outlet box becomes a junction box with a cover plate and an additional protected cable runs to the HPWC. HPWC gets set to a 50 Amp breaker/ 40 Amp charge rate.
If the wiring for the 14-50 was upsized, you may be able to increase the breaker/ charge rate.
 

boaterva

Well-Known Member
Supporting Member
Apr 2, 2016
7,594
3,835
Northern Virginia, USA
You might want to investigate doing what I did (see signature) and wiring to have a hardwired HPWC and a backup 14-50. Depends on how much of a belt and suspenders person you are!

I decided as long as I was getting two load-balancing HPWCs connected, I wanted a fallback in case lightning or something took them out!
 

mongo

Well-Known Member
May 3, 2017
14,002
45,563
Michigan
Good idea. If I leave the 14-50 NEMA alone what would I need to have added for a future HPWC? Add an additional 50 amp breaker to the board and run a wire from it in the wall and terminating in a empty junction box?

Sure. Depending on setup, you might be able to go conduit or wire in wall to HPWC and skip the junction box. (Not sure of code on unterminated wires). Or dual 14-50 to start.
 

Rocky_H

Well-Known Member
Feb 19, 2015
7,332
9,029
Boise, ID
The direct way is that you can just remove the outlet and mount the wall connector right there on those same wires. The 14-50 outlet uses four wires: Hot1, Hot2, Neutral, and ground. The wall connector will not need Neutral, so you can just put a wire nut on it to cap it off, and then connect the other three wires into the unit.
 
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GOPJEW

Member
Jul 5, 2015
571
264
Potomac, MD
If you want the full 100 amp (72 amp) capability of the HPWC then you will need to rewire everything - new breaker, possible junction breaker near HPWC (depending on code), plus new wiring.

If you just want to use it at the 42 amp the 14-50 can deliver, you can do as @Rocky_H suggested or even wire a plug into the HPWC as @rocksphoto showed.

Depends on what you want...
 

Rocky_H

Well-Known Member
Feb 19, 2015
7,332
9,029
Boise, ID
If you just want to use it at the 42 amp the 14-50 can deliver, you can do as @Rocky_H suggested or even wire a plug into the HPWC as @rocksphoto showed.
40A, by the way
*Edit* Oh, that's actually a very interesting point about being able to use your 50A circuit at the full 40A level. The original mobile cables could supposedly run at 40A, but seemed to be slightly underbuilt for that, and would sometimes have overheating/melting issues from that, just as the wall connectors also running at their maximum 80A level sometimes had those issues. So lots of owners were recommending to keep the mobile cables on a 14-50 set to the mid 30's amps to keep it a little bit cooler to extend the life of the cable. The new 2nd generation mobile cables will only do 32A anyway now.
So, since the wall connector is built to handle much higher currents, it would have no problem running at a full 40A, which is half what it is maximum rated for.
 
Last edited:

mxnym

Active Member
Mar 9, 2018
1,187
563
Bloomington, IN
Anyone know if the HPWC plugged into the 14-50 shown in video is "legal" codewise?
It may depend on the state, but if you wire it that way, presumably you'll take it with you when you move, so code technically won't be an issue (unless some state has random inspections or something). That having been said, if you can plug a range or a welder in, I don't really see how a the HPWC should be treated different than any other appliance, and in Indiana, for instance, many appliances come with the pigtail (wall wire) purchased separate if you self-install.
 

jboy210

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Supporting Member
Dec 2, 2016
5,984
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Northern California
It may depend on the state, but if you wire it that way, presumably you'll take it with you when you move, so code technically won't be an issue (unless some state has random inspections or something). That having been said, if you can plug a range or a welder in, I don't really see how a the HPWC should be treated different than any other appliance, and in Indiana, for instance, many appliances come with the pigtail (wall wire) purchased separate if you self-install.

Good point about the pigtail. I see them selling those things at the local Appliance stores with ranges and such. But I will check with the local codes.
 

davewill

Active Member
Feb 5, 2014
1,833
2,088
San Diego, CA, US
Anyone know if the HPWC plugged into the 14-50 shown in video is "legal" codewise?
It's an open question. @FlasherZ , the author of the charging FAQ, covers the subject. He comes to the conclusion that it may be a technical violation, but that most inspectors don't seem to be bothered by it. I wouldn't hesitate even a millisecond, myself. It if bothers you, you can always remove the receptacle and hardwire the wall connector instead. It's not much, if any, harder to do.
 

jboy210

Well-Known Member
Supporting Member
Dec 2, 2016
5,984
4,025
Northern California
It's an open question. @FlasherZ , the author of the charging FAQ, covers the subject. He comes to the conclusion that it may be a technical violation, but that most inspectors don't seem to be bothered by it. I wouldn't hesitate even a millisecond, myself. It if bothers you, you can always remove the receptacle and hardwire the wall connector instead. It's not much, if any, harder to do.

Thanks.

After talking to contractor, I am hoping the 14-50 outlet is a short term fix. We have a box already there with a 240V/50A, just missing the Nema 14-50 plug. So we are trying to get someone out right away to install the plug. I will use the Mobile charger with that.

Longer term I am waiting (and waiting ...) for my signature wall charger. When that comes we are looking to install it on a post that separates the two parts of the 3 car garage. We will remove the NEMA plug and run the 240V/50A line from there to the HPWC. That will let us have the ability to charge two Tesla EVs, just not at the same time.
 

bob_p

Active Member
Apr 5, 2012
3,738
2,944
We're going to face this issue whenever we get our "reward" HPWC. We already have a 14-50 outlet on that wall, with a Tesla 14-50 connector.
If we can use a pigtail from the HPWC to the 14-50 outlet, that would make installation much easier. Plus it would keep the 14-50 outlet available in case we ever wanted to connect it to something else (like a travel trailer).

If we can use a 14-50 connector to charge our Tesla, don't see why using a 14-50 pigtail to the HPWC would be a code issue - it's essentially just a different charging connection between the outlet and our X.
 

DCGOO

Active Member
Nov 24, 2015
1,825
1,107
Indianapolis, IN
We're going to face this issue whenever we get our "reward" HPWC. We already have a 14-50 outlet on that wall, with a Tesla 14-50 connector.
If we can use a pigtail from the HPWC to the 14-50 outlet, that would make installation much easier. Plus it would keep the 14-50 outlet available in case we ever wanted to connect it to something else (like a travel trailer).

If we can use a 14-50 connector to charge our Tesla, don't see why using a 14-50 pigtail to the HPWC would be a code issue - it's essentially just a different charging connection between the outlet and our X.

As long as the 14-50 is properly installed, you can plug anything you want in to it. The only possible disadvantage might be, if you installed a WC directly, you would not need to have a neutral, but the outlet requires one. I installed a 14-50 in my garage and have the pigtailed WC plugged into it. If I someday decide to upgrade to 72 amps, I will pull out the three #6 wires, and replace them with two #2. Unlikely I will ever do that, but it is possible.
 

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