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HPWC plugged into 14-50 - is this ok?

Moderatefan

Member
Dec 20, 2017
902
841
Denver, CO
I'm considering my future charging setup...Have read few threads and saw few people mentioned their HPWC or UMC units broke and stopped working, so they are not totally dependable.

Wondering if I can plug in HPWC into NEMA 14-50 outlet as a form of backup (if HPWC breaks, I can still use UMC with 14-50), also 14-50 will likely be more compatible with things non-Tesla. This also gives me the flexibility to have electrician install 14-50 and buy/self-install HPWC later.

I've read that HPWC is supposed to be hardwired. However, my sauna heater said the same. I really didn't want to do this, b/c that would remove my flexibility to easily unplug/move sauna unit when needed.
When I discussed this with my electrician (HVAC guy, actually) he said this doesn't make much difference, but gives manufacturer some leverage if, say, unit breaks and is on warranty and you want them to fix it, but they can say it was not wired up to spec, so it's your fault and we won't fix. Since my warranty on heater was only 1 year, I figured chances are pretty small I will need the warranty, so he added 14-50 outlet and the heater works fine since.

Is it the same kind of deal for HPWC? Are there electricians here to clarify dangers of such setup, like:
fires are more likely to happen;
If someone(?) sees this setup, they will void house insurance, charge penalties for non-compliance, etc. ?
 

oripaamoni

Member
Feb 2, 2018
268
233
San Diego
So I bought one of the rare units that comes from tesla with a 14-50 attached. As long as your wire going into the hpwc is well strain relieved and under 6ft you should be fine.
 

idoco

Member
May 7, 2013
552
604
Outside Philly
From FAQ FAQ: Home Tesla charging infrastructure Q&A
----------------------
CAN I ATTACH A CORD AND PLUG TO MY HPWC AT THE 50A SETTING?

In several threads on this forum, some have asked whether they may use their HPWC plugged into a NEMA 14-50 receptacle; this would allow them to unplug it and use their UMC in case of a wall connector failure.

Technically, there is nothing in the NEC that prohibits the practice; Tesla's instructions don't explicitly call for only permanent wiring methods, and article 625 permits 240V devices to be plug-and-cord devices as long as they're "fastened in place". The only restriction is that the segment of cord prior to the ground fault protection (HPWC) must be a maximum of 12 inches in length (NEC 625.17(A)(3)(a)). Proper connectors, clamps, and strain relief connectors must be used.

When consulted on the compliance of such a solution, several municipal and county inspectors have determined the practice to be legal based on the current instructions published by Tesla, and the NEC's requirements.

However, when consulted, Tesla expressed concerns about the practice. The charging team responded to an inquiry with an explanation that the HPWC is designed to be mounted on a wall or post and wired using permanent wiring methods. There are concerns that a power cord could be yanked from the HPWC's terminals and expose live wires if, for example, someone or something grabbed the cord and yanked.

A suggestion was made that Tesla note in the instruction/installation manual that permanent wiring methods are required, which would then be required by the NEC per section 110.3.
 

oripaamoni

Member
Feb 2, 2018
268
233
San Diego
Not sure why they never officially released this product, seems to be a good amount of people interred in it.
 

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Moderatefan

Member
Dec 20, 2017
902
841
Denver, CO
Well, the post from the FAQ pretty much says this is illegal and can be used to deny an insurance claim in case of a loss...especially if the fire started in that location (another FAQ topic "
  • SEVERAL TIMES IN THIS FAQ AND IN THESE FORUMS, YOU REFER TO INSURANCE AND LIABILITY ISSUES. WHAT DO YOU MEAN?)
Thanks for sharing this. Shoot. Not an answer I hoped for.
 

Moderatefan

Member
Dec 20, 2017
902
841
Denver, CO
So I bought one of the rare units that comes from tesla with a 14-50 attached. As long as your wire going into the hpwc is well strain relieved and under 6ft you should be fine.
Are you sure it came from Tesla, not a 3rd party?
How long ago? Wondering if they had since changed their position as described in post #3

Also found 3 options sold by Tesla in the past
Home Charging Installation

Your variation with 14-50 plug is not listed (bottom of the page)
 
Last edited:

Daniellane

Supporting Member
Aug 13, 2017
2,448
2,814
Camas, Washington
I'm considering my future charging setup...Have read few threads and saw few people mentioned their HPWC or UMC units broke and stopped working, so they are not totally dependable.

Wondering if I can plug in HPWC into NEMA 14-50 outlet as a form of backup (if HPWC breaks, I can still use UMC with 14-50), also 14-50 will likely be more compatible with things non-Tesla. This also gives me the flexibility to have electrician install 14-50 and buy/self-install HPWC later.

I've read that HPWC is supposed to be hardwired. However, my sauna heater said the same. I really didn't want to do this, b/c that would remove my flexibility to easily unplug/move sauna unit when needed.
When I discussed this with my electrician (HVAC guy, actually) he said this doesn't make much difference, but gives manufacturer some leverage if, say, unit breaks and is on warranty and you want them to fix it, but they can say it was not wired up to spec, so it's your fault and we won't fix. Since my warranty on heater was only 1 year, I figured chances are pretty small I will need the warranty, so he added 14-50 outlet and the heater works fine since.

Is it the same kind of deal for HPWC? Are there electricians here to clarify dangers of such setup, like:
fires are more likely to happen;
If someone(?) sees this setup, they will void house insurance, charge penalties for non-compliance, etc. ?
Are you limited to a 50 amp breaker?
If not, I’d go hardwired HPWC plus a NEMA 14-50 either direct to the main panel if it’s next to it or to a subpanel with 2 breakers.
My setup with a Backup NEMA 14-50.
802D708B-DA73-4287-A6FB-C5565723BB48.jpeg

HPWC on 100 amp Breaker Set to ON
Backup NEMA 14-50 just below HPWC on 50AMP breaker set to OFF

Also recently added a second HPWC which shares the 100 amp Breaker.
F722D226-1835-4E99-A911-E572C67D90C2.jpeg

18F748B9-2B33-41F1-8975-D19CCFD8C59F.jpeg
 

Moderatefan

Member
Dec 20, 2017
902
841
Denver, CO
Are you limited to a 50 amp breaker?
If not, I’d go hardwired HPWC plus a NEMA 14-50 either direct to the main panel if it’s next to it or to a subpanel with 2 breakers.
My setup with a Backup NEMA 14-50.
View attachment 292924
HPWC on 100 amp Breaker Set to ON
Backup NEMA 14-50 just below HPWC on 50AMP breaker set to OFF

Also recently added a second HPWC which shares the 100 amp Breaker.
View attachment 292926
View attachment 292927
Yeah, looks like your setup would be legal since HPWC is hardwired and 14-50 is a separate backup. Likely costs a bit more.
I thought my subpanel would be ~60 feet away in the basement, not sure how that would complicate things for HPWC.
 

oripaamoni

Member
Feb 2, 2018
268
233
San Diego
Are you sure it came from Tesla, not a 3rd party?
How long ago? Wondering if they had since changed their position as described in post #3

Also found 3 options sold by Tesla in the past
Home Charging Installation

Your variation with 14-50 plug is not listed (bottom of the page)

Ya its real for sure, Check out this youtube video on it. Mine is the exact one from that video, they sold it to me after they made the video.
 
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Daniellane

Supporting Member
Aug 13, 2017
2,448
2,814
Camas, Washington
Yeah, looks like your setup would be legal since HPWC is hardwired and 14-50 is a separate backup. Likely costs a bit more.
I thought my subpanel would be ~60 feet away in the basement, not sure how that would complicate things for HPWC.
I’m not an electrician. As I understand it, adequate sized wire is required to account for distance. One advantage of a subpanel is it can act as an emergency cutoff.
See this thread...
So I learned today that some places require a disconnect switch for circuits above 60A (please correct if wrong). I searched disconnect switch for 100A circuits and they are expensive. It seems easier to just install a 100A subpanel as a disconnect switch. Does this count as an appropriate disconnect switch?

$96
GE 100 Amp 240-Volt Fusible Outdoor General-Duty Safety Switch-TG3223R - The Home Depot

$133
Square D Circuit Breaker Enclosure, Surface, NEMA 1 FA100S | Zoro.com
 

Daniellane

Supporting Member
Aug 13, 2017
2,448
2,814
Camas, Washington
I'm considering my future charging setup...Have read few threads and saw few people mentioned their HPWC or UMC units broke and stopped working, so they are not totally dependable.

Wondering if I can plug in HPWC into NEMA 14-50 outlet as a form of backup (if HPWC breaks, I can still use UMC with 14-50), also 14-50 will likely be more compatible with things non-Tesla. This also gives me the flexibility to have electrician install 14-50 and buy/self-install HPWC later.

I've read that HPWC is supposed to be hardwired. However, my sauna heater said the same. I really didn't want to do this, b/c that would remove my flexibility to easily unplug/move sauna unit when needed.
When I discussed this with my electrician (HVAC guy, actually) he said this doesn't make much difference, but gives manufacturer some leverage if, say, unit breaks and is on warranty and you want them to fix it, but they can say it was not wired up to spec, so it's your fault and we won't fix. Since my warranty on heater was only 1 year, I figured chances are pretty small I will need the warranty, so he added 14-50 outlet and the heater works fine since.

Is it the same kind of deal for HPWC? Are there electricians here to clarify dangers of such setup, like:
fires are more likely to happen;
If someone(?) sees this setup, they will void house insurance, charge penalties for non-compliance, etc. ?
Is this for a Model 3?
If no this is may be an option:
Model S/X Corded Mobile Connector
 

Moderatefan

Member
Dec 20, 2017
902
841
Denver, CO
Is this for a Model 3?
If no this is may be an option:
Model S/X Corded Mobile Connector
Yes, this is M3 forum, so for M3. They sell similar gen2 UMC for S/X/3, which charges at max 32A vs 40A gen1(I believe can also be used for M3). I guess a bit slower compared what you can achieve with HPWC - direct connected to 60amp wire/breaker, the internal M3 LR charger can handle max 48 amp.
If I plug in UMC into 14-50 receptacle (40amp continuous) then I'd be limited by UMC - either 32amp or 40amp.
I guess it is also an option, I can buy 2nd UMC, which might be easier to handle (due to lighter cable) but will charge a bit slower.
This one would be legal to plug in to 14-50. So, a bit less hassle/cheaper, but somewhat slower. I think even 14-50 is enough to fully charge a car overnight, so the difference is largely non-existent until for some reason you need to charge fast and don't have much time.
 

azentropy

Member
Mar 26, 2018
183
109
Surprise, AZ
Ya its real for sure, Check out this youtube video on it. Mine is the exact one from that video, they sold it to me after they made the video.

Not sure why the didn’t release that version. Maybe couldn’t get the price point that would work. I’m probably going to just use my provided UMC at first at home as I figure 99% of the time I’ll charge at home, use a supercharger or a place that I’ll just need the j1772 adapter. But if a unit came out that provided 40A instead, could plug into my nema 14-50, and cost around the same as another UMC I’d consider it.
 

Moderatefan

Member
Dec 20, 2017
902
841
Denver, CO
if a unit came out that provided 40A instead, could plug into my nema 14-50, and cost around the same as another UMC I’d consider it.
Gen1 is not reliable, that's why it's replaced by Gen2, plus $500 vs $300 difference... I think for $500 it makes more sense to buy HPWC.

Or do you really need the appearance of the wall mounted-ness?
It's not just mounted-ness. It's more safe, more amps (for LR), and HPWCs can auto-split the charge among multiple cars on the same circuit.
 
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Reactions: TexasEV

TexasEV

Well-Known Member
Jun 5, 2013
7,646
8,481
Austin, TX
The Gen 1 UMC that came with my Model S was much more reliable— it lasted 4 years. So far I’m on my third Gen 2 UMC with my Model 3 which was delivered a month ago. The first one had a button so difficult to push that it usually didn’t open the charge port or release the connector. The replacement had ground faults intermittently (reproduced at the service center—it wasn’t my outlet). The replacement for the replacement has worked fine.
 

Moderatefan

Member
Dec 20, 2017
902
841
Denver, CO
The Gen 1 UMC that came with my Model S was much more reliable— it lasted 4 years. So far I’m on my third Gen 2 UMC with my Model 3 which was delivered a month ago. The first one had a button so difficult to push that it usually didn’t open the charge port or release the connector. The replacement had ground faults intermittently (reproduced at the service center—it wasn’t my outlet). The replacement for the replacement has worked fine.
I said safe, not reliable. While defects are possible in both, I believe a number of people had issues with varying amperage and near fires due to plug/unplug cycles and bad connection/overheating at the outlet as a result; I think to deal with that Tesla reduced amperage, but maybe also to lower the price point due to thinner cable. Not guaranteeing, just a feeling I got from reading multuple threads here...
 

TexasEV

Well-Known Member
Jun 5, 2013
7,646
8,481
Austin, TX
I said safe, not reliable. While defects are possible in both, I believe a number of people had issues with varying amperage and near fires due to plug/unplug cycles and bad connection/overheating at the outlet as a result; I think to deal with that Tesla reduced amperage, but maybe also to lower the price point due to thinner cable. Not guaranteeing, just a feeling I got from reading multuple threads here...
Your post started by saying “Gen 1 is not reliable.”
 

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