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Can I install the HPWC and a NEMA 14-50 connector from a single line?

JonB65

Member
Oct 8, 2020
9
4
Maryland
I'm having my Tesla HPWC installed in the next week or two. I was watching this video and thought having the NEMA 14-50 in parallel was a good idea, in case the HPWC failed for any reason. Teeing off the power line and running one side to the HPWC and the other to the 14-50. What I was trying to figure out is how GFCI plays into this. Tesla says not to use a GFCI breaker, but does code say the 14-50 needs to be on a GFCI circuit? How could I reconcile both of these?

Or, should I just install the HPWC and not worry about having a backup? Just trying think ahead and be covered in case the HPWC would fail for any reason.

 

jcanoe

Active Member
Oct 2, 2020
1,504
1,548
Maryland
That would be a clear code violation as the circuit must be dedicated with only one receptacle or one electrical device.

Depending on the length of the wiring required you could save a little money by just hard wiring the Wall Connector as intended; the Wall Connector only requires 2 wires (plus ground); the NEMA 14-50 requires 3 wires plus ground.

You could install a NEMA 14-50 receptacle and then wire a 14-50 plug on the supply side of the Wall Connector. The Wall Connector would have to be set for 50A circuit or less. You could only set the Wall Connector for 60A circuit if the Wall Connector was hard wired to a 60A circuit and wiring.
 

Stavinski

Member
Jan 31, 2021
43
44
USA
I had both installed on separate circuits. It wasn’t much more in labor to install a second circuit.
I had two circuits run as well. In my case the run was pretty short and additional cost was rounding error, just a bit of wire and a box/plug for $25 or something. this option also permits the possibility of a second car charging at high current without incurring a visit by an electrician or the fire department. I only have 1 EV today but who knows what the future will bring.
 

JonB65

Member
Oct 8, 2020
9
4
Maryland
Thanks all. My run is from the garage to the basement breaker box on the other side of the house. About 40 feet. Best to do two runs if I want this. I appreciate the responses.
 

jstjohnz

Member
Sep 7, 2020
96
46
Indianapolis
That would be a clear code violation as the circuit must be dedicated with only one receptacle or one electrical device.

Depending on the length of the wiring required you could save a little money by just hard wiring the Wall Connector as intended; the Wall Connector only requires 2 wires (plus ground); the NEMA 14-50 requires 3 wires plus ground.

You could install a NEMA 14-50 receptacle and then wire a 14-50 plug on the supply side of the Wall Connector. The Wall Connector would have to be set for 50A circuit or less. You could only set the Wall Connector for 60A circuit if the Wall Connector was hard wired to a 60A circuit and wiring.

What is the code violation?
 

jstjohnz

Member
Sep 7, 2020
96
46
Indianapolis
I believe that in most cases multiple receptacles are not prohibited but there is a requirement that EV charging equipment must be on a dedicated circuit.
 
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jcanoe

Active Member
Oct 2, 2020
1,504
1,548
Maryland
I believe that in most cases multiple receptacles are not prohibited but there is a requirement that hard-wired EV charging equipment must be on a dedicated circuit.
It has been a while but I recall reading that the limit for having multiple receptacles was either 20A or 25A.
 

Rocky_H

Well-Known Member
Feb 19, 2015
5,970
6,889
Boise, ID
What is the code violation?
I believe that in most cases multiple receptacles are not prohibited but there is a requirement that EV charging equipment must be on a dedicated circuit.
It's this. It's in section 625, that is all about EV charging. It does say that any circuit for EV charging must be dedicated, with only one thing on it.
A 240V/50A circuit must be a dedicated circuit, i.e. cannot have multiple outlets or an outlet and other equipment on the same circuit.
It has been a while but I recall reading that the limit for having multiple receptacles was either 20A or 25A.
No, there are allowances for multi-outlet circuits going higher, and in fact a table of what outlet types can go on multi-outlet circuits up to 40 and 50A. The use case that is frequently talked about as an example for this electric code consideration is an industrial shop of some kind that is fairly large, and it may have a portable (like rolling) high amp device, like a saw or welder or something that may need to be moved from one side of the shop to the other. So you can put two or three of those outlets on different sides of the shop that are on the same circuit, because the intent is to move that piece of equipment around, but there will only be that one plugged in anywhere.
 
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jcanoe

Active Member
Oct 2, 2020
1,504
1,548
Maryland
It's this. It's in section 625, that is all about EV charging. It does say that any circuit for EV charging must be dedicated, with only one thing on it.


No, there are allowances for multi-outlet circuits going higher, and in fact a table of what outlet types can go on multi-outlet circuits up to 40 and 50A. The use case that is frequently talked about as an example for this electric code consideration is an industrial shop of some kind that is fairly large, and it may have a portable (like rolling) high amp device, like a saw or welder or something that may need to be moved from one side of the shop to the other. So you can put two or three of those outlets on different sides of the shop that are on the same circuit, because the intent is to move that piece of equipment around, but there will only be that one plugged in anywhere.
Thank you for your correction. What would concern me is that repeated plugging/unplugging equipment from multiple 50A receptacles (as far as I know there is no specific 40A receptacle) is not compatible with the intended duty cycle of the typical 14-50R, etc.

Regarding the EV charging circuit being dedicated, I know that ClipperCreek sells an EVSE (several models as I recall) that enable two (possibley more than two) hard wired ClipperCreek HCS series EVSE units to share a single circuit (using ClipperCreek's wired load balancing.) Would this not be a violation of section 625? Also, although not yet available Tesla has stated that the Wall Connector will support load balancing via WiFI, isn't that also in conflict with section 625?
 
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Rocky_H

Well-Known Member
Feb 19, 2015
5,970
6,889
Boise, ID
Regarding the EV charging circuit being dedicated, I know that ClipperCreek sells an EVSE (several models as I recall) that enable two (possibley more than two) hard wired ClipperCreek HCS series EVSE units to share a single circuit (using ClipperCreek's wired load balancing.) Would this not be a violation of section 625? Also, although not yet available Tesla has stated that the Wall Connector will support load balancing via WiFI, isn't that also in conflict with section 625?
Well no, I just forgot to mention that part, because I was talking about just a simple single device. Section 625.42 is the allowance specifically for EVSE models that have automatic load management systems to not exceed the rating of the circuit they are on, and that is specifically allowed. Here's the wording on that.

 
Mar 2, 2021
33
14
Michigan
My electrician said I can have two Nema 14-50 outlets so long as only one is being used and plugged into at any given time. So I could have one outside and inside and use the one I need at that time.... I don't know code nor do I care to.
 

Rocky_H

Well-Known Member
Feb 19, 2015
5,970
6,889
Boise, ID
My electrician said I can have two Nema 14-50 outlets so long as only one is being used and plugged into at any given time. So I could have one outside and inside and use the one I need at that time.... I don't know code nor do I care to.
Your electrician is saying stuff based on long time traditional information, but that is now old and outdated knowledge. That could have been true--used to be true--under old versions of code and if this were not for electric vehicle charging. That's what it used to be for regular general purpose 14-50 outlets under the NEC up through the 2014 version. With the 2017 version, they put in a whole very large section 625 that is all about EV charging, and it forbids that. (That is also when they added the requirement to use GFCI breakers for outlets used for EV charging.) Most states have gone to at least the 2017 version of NEC.

I'll amend this to say that depending on the state, that may not be wrong, if it's one that is still on the 2014 version or older. Those states are Montana, Oklahoma, Louisinana, Alabama, Virginia, Pennsylvania, Maryland, Delaware, and Indiana. But you're in Michigan, which has adopted NEC 2017, so that doesn't apply.
 
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[email protected]

What, me worry?
Mar 8, 2021
6
6
45241
You can run a heavier cable to a new subpanel in your garage, and then have multiple devices wired off of the subpanel. This won't add too much cost as you only run one set of heavier wires from the main panel - and a sub-panel isn't too expensive.
 
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jsight

Member
Apr 5, 2018
439
242
Charleston
Its too bad that transfer switches are so expensive. A backup outlet like this would be a nice thing to have, but obviously you wouldn't want to run it in parallel with the HPWC.
 
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BigTrailer

Member
Mar 18, 2021
48
29
Toronto, Canada
I have two JuiceBox Pro 40's installed on a single 50 amp circuit. They do load balancing as to never exceed the total of 40amps.

I own two EV's and I have family members with non-Tesla EV's. I didn't really see a big advantage with going proprietary on the charger, when my JuiceBox chargers do the same job without being locked into the Tesla universe.
 
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Rocky_H

Well-Known Member
Feb 19, 2015
5,970
6,889
Boise, ID
Its too bad that transfer switches are so expensive. A backup outlet like this would be a nice thing to have, but obviously you wouldn't want to run it in parallel with the HPWC.
Well, expense is kind of relative. People on this forum all the time tell people to blow $500 on a wall connector they don't need. The transfer switches for things like this that can toggle between loads up to 60A are $120. If you're already getting a few hundred dollars worth of electrical work done, that's in the ballpark to add to it.
 
Mar 2, 2021
33
14
Michigan
Your electrician is saying stuff based on long time traditional information, but that is now old and outdated knowledge. That could have been true--used to be true--under old versions of code and if this were not for electric vehicle charging. That's what it used to be for regular general purpose 14-50 outlets under the NEC up through the 2014 version. With the 2017 version, they put in a whole very large section 625 that is all about EV charging, and it forbids that. (That is also when they added the requirement to use GFCI breakers for outlets used for EV charging.) Most states have gone to at least the 2017 version of NEC.

I'll amend this to say that depending on the state, that may not be wrong, if it's one that is still on the 2014 version or older. Those states are Montana, Oklahoma, Louisinana, Alabama, Virginia, Pennsylvania, Maryland, Delaware, and Indiana. But you're in Michigan, which has adopted NEC 2017, so that doesn't apply.
To be clear, it sounds like I am probably to code still then. I have a 50A circuit from my main that feeds a subpanel with two 50A circuits. Off each of those is one Nema 14-50 in which I can only use one at a time. If I were to use both I would absolutely blow the 50A main but not the 50A for that individual ciruit. Also was done prior to 2017 anyways.
 

Mrbrock

Member
Mar 26, 2020
566
300
Napa, CA
You knowing that you can only use one receptacle at a time doesn’t allow it to pass code. If you move, the new resident will not know and can cause damage by trying to use both at once. I believe your situation is still not to code because the 50A circuit feeding two 50A receptacles that are used for EV charging would be subject to constant use so 50 + 50 is 100 so the circuit would have to be rated for 100A to meet code. Or have some type of physical switch to only allow you to use one device at a time.
 
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