Concerns about NEMA 6-50R in new home

[FlasherZ]

Yeah, that will work. I'm pretty sure (99%) that no codes would be violated. Your UMC would only be pulling 40 amps anyway, 20% less than the rated 50 amps of the outlet.

NEMA 14-50 receptacles have an instruction sheet which specify that it be fed with a 4-wire circuit. You violate 110.3 when you ignore that. Will the electrical police come by and validate it, writing you a ticket? Probably not, but down the road you might find insurance or liability implications should something go wrong. If it's a permanent installation, I always recommend you do it the right way - and that means pulling new cable to the receptacle location.

In addition, the UMC operating at 40A draw requires a 50A rated conductor, breaker, and receptacle because of the requirement for continuous load overhead (125%). So it's not 20% less, it's rated right at what's required because of the continuous load requirements.

 

[FlatSix911]

Good recommendation here from Flasher ... FAQ: Home Tesla charging infrastructure Q&A

I HAVE ACCESS TO A NEMA 6-50 WELDER OUTLET. CAN I BUILD AN ADAPTOR CORD TO THE TESLA UMC’S STANDARD 14-50 PLUG?

Tesla has discontinued its NEMA 6-50 adapter, and therefore there is no longer an option to connect to NEMA 6-50 (welder) outlets using a native UMC adapter.

While one of these cables can be safely used with the Tesla EV, you must be careful as it carries a significant risk to someone who would try to use it for another application. In particular, this adaptor might be used by someone looking to connect an RV. RV’s typically have many 120V loads, and as a NEMA 6 series connector does not provide a neutral conductor, 120V appliances can be destroyed if this adapter cord is used for an RV. Other appliances that require 120V (electric ranges, for example, for timer and clock circuits) may also not work properly if this adapter is used. Always properly label any adapter cords that you make for the Tesla as "FOR TESLA CHARGING ONLY".

To make such an adaptor, use a short length of type SOOW 6/3 cord. Connect the black and white wires (if using 6/3 cord), or black and red (if using 6/4) to the respective brass terminals on the NEMA 6-50P and NEMA 14-50R, and the green wire of the cord to the green terminals of the plug and receptacle. Label and store this cable per the above instructions, and add “NO NEUTRAL – DO NOT USE FOR RV’S” to the label. Under no circumstances should you ever connect the neutral pin of a NEMA 14-50 receptacle to the equipment grounding conductor (ground) - this is unsafe and dangerous.

You may want to consider filling in the neutral pin of your 14-50R with epoxy, and cutting off the neutral pin of the UMC’s 14-50P (it is unconnected and unused by the UMC) to prevent this cord from being used with an RV. This will invalidate your UMC’s warranty but will provide an added level of protection in that the 14-50 cannot be used for appliances that need a neutral.

This type of adapter carries potential liability and insurance implications, but is operationally safe to use.

 

[HankLloydRight]

Thanks FlasherZ for the corrections! (That's why I said "99%").

I shall not post on such topics again.

 

[HankLloydRight]

In addition, the UMC operating at 40A draw requires a 50A rated conductor, breaker, and receptacle because of the requirement for continuous load overhead (125%). So it's not 20% less, it's rated right at what's required because of the continuous load requirements.

Right -- I got confused thinking the 6-50 had a higher rated feed than the 14-50. It's not higher, it's just different. Nevermind (again).

 

[ChrisH]

NEMA 14-50 receptacles have an instruction sheet which specify that it be fed with a 4-wire circuit. You violate 110.3 when you ignore that. Will the electrical police come by and validate it, writing you a ticket? Probably not, but down the road you might find insurance or liability implications should something go wrong. If it's a permanent installation, I always recommend you do it the right way - and that means pulling new cable to the receptacle location.

In addition, the UMC operating at 40A draw requires a 50A rated conductor, breaker, and receptacle because of the requirement for continuous load overhead (125%). So it's not 20% less, it's rated right at what's required because of the continuous load requirements.

Well shoot. So what you're saying is that I really should have an electrician come out and install a 14-50? How much would that generally cost given the current setup?

 

[Galve2000]

IMO Tesla really screwed us when they discontinued the NEMA 6-50 prongs for the UMC.

This is why I say this:

NEMA 14-50 receptacles have an instruction sheet which specify that it be fed with a 4-wire circuit. You violate 110.3 when you ignore that...down the road you might find insurance or liability implications should something go wrong. If it's a permanent installation,

 

[FlasherZ]

Well shoot. So what you're saying is that I really should have an electrician come out and install a 14-50? How much would that generally cost given the current setup?

That'd be the right way to fix it.

As noted, the use of the adapter isn't as bad as using an adapter to plug the 14-50 into a 30A outlet. Technically, it's illegal but I know several who use them (the 14-50 to 6-50 adapter). Just label it VERY WELL.

 

[ChrisH]

That'd be the right way to fix it.

As noted, the use of the adapter isn't as bad as using an adapter to plug the 14-50 into a 30A outlet. Technically, it's illegal but I know several who use them (the 14-50 to 6-50 adapter). Just label it VERY WELL.

Could an electrician simply install a 14-50 near my electrical box in the garage? The 6-50 is across the garage from it. I don't know if the circuits and such are all at the panel or what. I guess I will just have to an electrician come out and take a look at it. Just hoping it doesn't require a ton of additional wiring or expensive add ons.

 

[CmdrThor]

Nothing is definite. It depends on the wiring that's already installed.

That is true. I even have a 6-50 in my garage that has a neutral wire capped off, suppose I should have thought of that.

 

[FlasherZ]

Could an electrician simply install a 14-50 near my electrical box in the garage? The 6-50 is across the garage from it. I don't know if the circuits and such are all at the panel or what. I guess I will just have to an electrician come out and take a look at it. Just hoping it doesn't require a ton of additional wiring or expensive add ons.

Sure - installing a new circuit (decommissioning the old one if required by load or panel room standards) is a definite possibility.

 

[gaswalla]

Did you ask Tesla for the 6-50 adapter and tell them your story? I have a 4 years old Model S, with 6-50 at home, adapter melted, and they very recently gave me a new one. Just ask nicely! Tesla folks are good peeps

 

[ChrisH]

Did you ask Tesla for the 6-50 adapter and tell them your story? I have a 4 years old Model S, with 6-50 at home, adapter melted, and they very recently gave me a new one. Just ask nicely! Tesla folks are good peeps

Ha. Well....I don't own a Tesla yet. Just trying to future proof my garage but it looks like I've got the wrong set up!!!

 

[tga]

Ha. Well....I don't own a Tesla yet. Just trying to future proof my garage but it looks like I've got the wrong set up!!!

When the time comes, it may be cheaper to install the new HPWC @ $500-$550 (depending on cable length) using the existing wiring than pull a new 4 wire circuit, especially if you were thinking about getting a second UMC (at $650) to leave in the garage.

 

[Rocky_H]

When the time comes, it may be cheaper to install the new HPWC @ $500-$550 (depending on cable length) using the existing wiring than pull a new 4 wire circuit, especially if you were thinking about getting a second UMC (at $650) to leave in the garage.

Yeah, a couple of things. The 6-50 to 14-50 adapter cable will work just fine for your Tesla. It’s safe as far as current levels, since it’s 50A to 50A, and is probably the cheapest solution, at $55 to buy from EVSEAdapters or just make your own.


However, it’s going to be a little cumbersome, having a cable to another cable. And if you’re considering doing any other electrical work to rewire the outlet or install a new 14-50, that’s going to run you at least a few hundred dollars. Getting the Tesla wall connector at $550 seems the best value at that point. You can take out the 6-50 outlet and install the wall connector on that existing wiring. It now gives you the opportunity to keep your mobile charge cable in the trunk, and it’s a bit more solid installation, being hardwired, than the one with plugs and outlets. The mobile cable does get a little hot at 40A, whereas the wall connector is a thicker wire, so 40A stays plenty cool. So yeah, I think just putting in the wall connector is better than any other wiring installation alternative.

 

[ChrisH]

How come the

Yeah, a couple of things. The 6-50 to 14-50 adapter cable will work just fine for your Tesla. It’s safe as far as current levels, since it’s 50A to 50A, and is probably the cheapest solution, at $55 to buy from EVSEAdapters or just make your own.


However, it’s going to be a little cumbersome, having a cable to another cable. And if you’re considering doing any other electrical work to rewire the outlet or install a new 14-50, that’s going to run you at least a few hundred dollars. Getting the Tesla wall connector at $550 seems the best value at that point. You can take out the 6-50 outlet and install the wall connector on that existing wiring. It now gives you the opportunity to keep your mobile charge cable in the trunk, and it’s a bit more solid installation, being hardwired, than the one with plugs and outlets. The mobile cable does get a little hot at 40A, whereas the wall connector is a thicker wire, so 40A stays plenty cool. So yeah, I think just putting in the wall connector is better than any other wiring installation alternative.

Thanks. I guess I'm confused how the wall connector can be installed on my current wiring and work correctly when the 14-50 standard charging outlet needs 4 wires. I clearly have no experience with electrical.

 

[tga]

How come the


Thanks. I guess I'm confused how the wall connector can be installed on my current wiring and work correctly when the 14-50 standard charging outlet needs 4 wires. I clearly have no experience with electrical.

A legal and safe 14-50 outlet requires 4 wires - 2 hots, a neutral, and a ground. You get 240V across the 2 hots and 120V between either hot and the neutral, which is why it's called a 120V/240V outlet. The 6-50 outlet does not have the neutral - it is a 240V outlet only.

The problem with switching you to a 14-50 is that we don't know if there's a neutral wire in place. If there is, you just hook up the 4 wires and you're ready to go. If there isn't, you need to add one, which could get expensive, depending on the complexity of your current installation.

The HPWC does not need or use the neutral wire. So installing it in place of the 6-50 is just connecting the three wires (hot/hot/ground) and setting the switches to configure the HPWC to a 40A charge rate.

 

[FlasherZ]

Thanks. I guess I'm confused how the wall connector can be installed on my current wiring and work correctly when the 14-50 standard charging outlet needs 4 wires. I clearly have no experience with electrical.

Because the UMC and HPWC don't use the neutral. NEMA 6 standard is L1+L2+ground and can only provide 240V to appliances... NEMA 14 standard is L1+L2+neutral+ground and can provide 240V and 120V to appliances at the same time. Tesla UMC & HPWC only need 240V. But other things that plug into 14-50's need that neutral to be present -- RV's need it because they have a lot of 120V appliances, and stoves need it to run the clock, oven light, etc.

That's why I say above that the 14-50 to 6-50 adapter cord will work; however, if you try to use it to plug in any other 14-50 device you'll end up likely smoking some appliances.

 

[ZBB]

Flasher -
You are a great resource here and do a really great job describing things in a way nearly everyone can understand. Thank you for all the posts like this!

 

[Rocky_H]

Here’s the one side note to go with it. Tesla could have recommended 6-50 as their standard charging outlet, right? They only use the 240V for charging. As a matter of fact, in the 14-50 adapter on your mobile charge cable, that neutral blade isn’t even connected. It’s just there for standard structural purposes for fitting into the outlet nicely. So why would they go with 14-50? I think it is basically this: 6-50 outlets are not very commonly found around the country. However, most campgrounds and RV parks have 14-50 outlets at their hookup spots. It was Tesla doing something nice for us, that they designed in a standard for charing that gave us access to thousands of additional recharging sites nationwide.

 

[FlasherZ]

Here’s the one side note to go with it. Tesla could have recommended 6-50 as their standard charging outlet, right? They only use the 240V for charging. As a matter of fact, in the 14-50 adapter on your mobile charge cable, that neutral blade isn’t even connected. It’s just there for standard structural purposes for fitting into the outlet nicely. So why would they go with 14-50? I think it is basically this: 6-50 outlets are not very commonly found around the country. However, most campgrounds and RV parks have 14-50 outlets at their hookup spots. It was Tesla doing something nice for us, that they designed in a standard for charing that gave us access to thousands of additional recharging sites nationwide.

Absolutely right. There is one other element - those 6-50's that are out there are typically of a wider variety of specifications. Welders can be provisioned on 6-50's with a very wide variety of currents and wiring selection. Most 14-50's out there are pretty standardized @ 50A (with some range receptacles at 40A).