Charging from NEMA 6-20 using NEMA 5-20 Adapter

[davewill]

Am having the electrician build the pigtail for me, he has installed the 6-20 for me. He thinks I would work but his concern is that the 5-20 is not rated for 240V so it could technically fry, is that a concern?

Should be fine for the same reason you didn't need new wiring to convert your circuit to 240v. The voltage over ground is still only 120v, you just have two hots instead of one. That said, buy a good quality 5-20r and it would be good to inspect it carefully for heat the first few times you use it... Of course that goes for anything new.

 

[krazineurons]

Should be fine for the same reason you didn't need new wiring to convert your circuit to 240v. The voltage over ground is still only 120v, you just have two hots instead of one. That said, buy a good quality 5-20r and it would be good to inspect it carefully for heat the first few times you use it... Of course that goes for anything new.

thanks, I ordered the parts as recommended from the thread.. Happy to be charging at 9mi/hr now with 12A/240V using tesla 5-15 adapter and UMC. I am a happy camper, thanks all the wonderful folks here.

 

[TonyWilliams]

You can be assured that all the wiring and components are rated for 300 V and maybe even 600 V.

 

[n2mb_racing]

Hi all,

I thought I'd contribute the solution I'm planning. I'm trying to find the highest quality cable and connectors to make this as safe as possible. I have installed a NEMA 6-20 receptacle, fed with 12AWG copper wire and connected to a new 20A dual (240V) breaker.

However, the plug is a bit far away in my garage, so I need a 25 ft extension cord. There is a pre-made NEMA 6-20 extension cord that could be used with the Tesla 6-15 UMC adapter with no modifications, but I'd only get 12A charging:
Amazon.com: NEMA 6-20 Extension Power Cord - 25 Foot, 20A/250V, 12/3 SJT - Iron Box # IBX-6153-25: Home Audio & Theater

I'd need to chop off the NEMA 6-20R and put on a 5-20R to get 16A charging.

So, I might start with this 25ft cable which has a NEMA 5-20R:
Amazon.com: Conntek NEMA 5-20 20-Amp T-Blade SJOOW 12/3 Anti-Weather, Oils, Acids and Chemicals Rubber Extension Cord, 25-Feet: Sports & Outdoors

then cut off the plug and add a NEMA 6-20 plug:
Leviton 5466-C 20 Amp, 250 Volt, Plug, Straight Blade, Industrial Grade, Grounding, Black-White - Electric Plugs - Amazon.com

(In case anyone needs it, the corresponding Leviton high-quality NEMA 5-20R is: Leviton 5369-C 20 Amp, 125 Volt, Connector, Industrial Grade, Straight Blade, Grounding, Black-White - Electric Plugs - Amazon.com )

I'm using a less nice solution now, but I've tested charging at both 240V @ 12A and 240V at 16A.

My efficiency data is as following:
12A 88.0%
16A 90.7%
24A 93.1%

and probably a smaller improvement when you go to 40A, but not by much. My data is from Teslafi and could be noisy. It is averaged over a few charging cycles.

So, getting to 16A is probably a good idea.

 

[davewill]

Hi all,

I thought I'd contribute the solution I'm planning. I'm trying to find the highest quality cable and connectors to make this as safe as possible. I have installed a NEMA 6-20 receptacle, fed with 12AWG copper wire and connected to a new 20A dual (240V) breaker.

However, the plug is a bit far away in my garage, so I need a 25 ft extension cord. There is a pre-made NEMA 6-20 extension cord that could be used with the Tesla 6-15 UMC adapter with no modifications, but I'd only get 12A charging:
Amazon.com: NEMA 6-20 Extension Power Cord - 25 Foot, 20A/250V, 12/3 SJT - Iron Box # IBX-6153-25: Home Audio & Theater

I'd need to chop off the NEMA 6-20R and put on a 5-20R to get 16A charging.

So, I might start with this 25ft cable which has a NEMA 5-20R:
Amazon.com: Conntek NEMA 5-20 20-Amp T-Blade SJOOW 12/3 Anti-Weather, Oils, Acids and Chemicals Rubber Extension Cord, 25-Feet: Sports & Outdoors

then cut off the plug and add a NEMA 6-20 plug:
Leviton 5466-C 20 Amp, 250 Volt, Plug, Straight Blade, Industrial Grade, Grounding, Black-White - Electric Plugs - Amazon.com

(In case anyone needs it, the corresponding Leviton high-quality NEMA 5-20R is: Leviton 5369-C 20 Amp, 125 Volt, Connector, Industrial Grade, Straight Blade, Grounding, Black-White - Electric Plugs - Amazon.com )

I'm using a less nice solution now, but I've tested charging at both 240V @ 12A and 240V at 16A.

My efficiency data is as following:
12A 88.0%
16A 90.7%
24A 93.1%

and probably a smaller improvement when you go to 40A, but not by much. My data is from Teslafi and could be noisy. It is averaged over a few charging cycles.

So, getting to 16A is probably a good idea.

I'd be leery about modding the extension cord. It would be too easy for someone to pick up the 5-20 end and plug something into it (Ziiiip! Arc). Better, I think, to make a separate short adapter that you can label "EV Only" in large, friendly letters.

 

[n2mb_racing]

I'd be leery about modding the extension cord. It would be too easy for someone to pick up the 5-20 end and plug something into it (Ziiiip! Arc). Better, I think, to make a separate short adapter that you can label "EV Only" in large, friendly letters.

Thought about that. You could make a nice, short adapter using this cord:
Amazon.com: Conntek 1F515520 1-Foot 15-Amp to 20-Amp Power Adapter Cord NEMA 5-15P to 5-15/20R 1F515520: Patio, Lawn & Garden

However, I didn't want to add an additional connection that introduces more resistance, heat and power loss. It also adds another point of failure in the system... I will definitely label the extension cord on both ends!

 

[DarkMatter]

Thought about that. You could make a nice, short adapter using this cord:
Amazon.com: Conntek 1F515520 1-Foot 15-Amp to 20-Amp Power Adapter Cord NEMA 5-15P to 5-15/20R 1F515520: Patio, Lawn & Garden

However, I didn't want to add an additional connection that introduces more resistance, heat and power loss. It also adds another point of failure in the system... I will definitely label the extension cord on both ends!

If properly constructed the power loss is tiny. If it were losing more than a few watts it would be too hot to touch. I'd take the safety of it being obvious over the few cents a year of saved energy.

 

[n2mb_racing]

If properly constructed the power loss is tiny. If it were losing more than a few watts it would be too hot to touch. I'd take the safety of it being obvious over the few cents a year of saved energy.

Good point.... Ok, maybe I'll use the NEMA 6-20 extension with no modifications and build a short adapter from NEMA 6-20 to 5-20 using this:
Amazon.com: Conntek 1F515520 1-Foot 15-Amp to 20-Amp Power Adapter Cord NEMA 5-15P to 5-15/20R 1F515520: Patio, Lawn & Garden
and this:
Leviton 5466-C 20 Amp, 250 Volt, Plug, Straight Blade, Industrial Grade, Grounding, Black-White - Electric Plugs - Amazon.com

Thanks!

 

[n2mb_racing]

Another way to build this adapter for $26 in parts. I think I like this option better than the one I posted above.

NEMA 6-20P 1 foot cable for $15:
Amazon.com: NEMA 6-20P to C19 Power Cord - 1 Foot, 20A/250V, 12/3 SJT - Iron Box # IBX-4937-01M: Home Audio & Theater

NEMA 5-20R socket for $11
Leviton 5369-C 20 Amp, 125 Volt, Connector, Industrial Grade, Straight Blade, Grounding, Black-White - Electric Plugs - Amazon.com

 

[Cellsaver]

I followed @davewill advice from another thread and converted a 5-20r to a 6-20r/240 volt in my garage. Then built an adaptor so I can use Tesla's 5-20p to automatically set 16 amps. Works great and could be a much cheaper option for many people who have detached garages that would lead to expensive 14-50 installs. None of the electricians I had come out even mentioned it as an option, I had to tell them specifically what I wanted.

 

[miimura]

I followed @davewill advice from another thread and converted a 5-20r to a 6-20r/240 volt in my garage. Then built an adaptor so I can use Tesla's 5-20p to automatically set 16 amps. Works great and could be a much cheaper option for many people who have detached garages that would lead to expensive 14-50 installs. None of the electricians I had come out even mentioned it as an option, I had to tell them specifically what I wanted.

Any electrician can tell you the maximum amps that can be safely installed, but I would never expect them to be able to connect the dots to tell you how to safely put exactly that many amps into your Tesla.

 

[Cellsaver]

The home-made adapter part I agree on, but I think the Tesla recommended electricians should at least be able to say that Tesla makes a 6-15 adapter and you could easily convert an existing 5-20 or 5-15 to a 6-15 and more than double your hourly charge miles. 10-11 mile/hr charge is plenty for many people, so this can be a great option for detached garages that would require pricey trenching and long cable runs.

 

[n2mb_racing]

The home-made adapter part I agree on, but I think the Tesla recommended electricians should at least be able to say that Tesla makes a 6-15 adapter and you could easily convert an existing 5-20 or 5-15 to a 6-15 and more than double your hourly charge miles. 10-11 mile/hr charge is plenty for many people, so this can be a great option for detached garages that would require pricey trenching and long cable runs.

I wish Tesla would make a 6-20 adapter. They only have 6-15.

I get 8 mph @ 240V 12A and 11 mph @ 240V 16A.

 

[Cellsaver]

I wish Tesla would make a 6-20 adapter. They only have 6-15.

I get 8 mph @ 240V 12A and 11 mph @ 240V 16A.

The adaptor is easy to make, you use the Tesla 20amp/120V 5-20 adaptor on the end of your UMC, then just make a 5-20r to 6-20p adaptor. Works like a charm and took me 30 seconds (and I know next to nothing about wiring).

 

[n2mb_racing]

Yup, see post #109 above for recommended parts.

 

[rmnelson]

I'm sorry to ask such a noob question. I've got the parts. I've wired up outlets and extension cords before using printed instructions with pictures. Before I tighten the screws and plug the thing into my garage 6-20 outlet and the UMC, I want to make absolutely sure that I am not going zap myself, my UMC, or the house for that matter. I connected the center green wire to the ground screw and have two remaining wires. One remaining terminal has a black screw, the other is silver. I've attached a picture of the 6-20P pigtail with the 5-20R. Do I just connect each of the remaining wires to the open terminals?

 

[tga]

I'm sorry to ask such a noob question. I've got the parts. I've wired up outlets and extension cords before using printed instructions with pictures. Before I tighten the screws and plug the thing into my garage 6-20 outlet and the UMC, I want to make absolutely sure that I am not going zap myself, my UMC, or the house for that matter. I connected the center green wire to the ground screw and have two remaining wires. One remaining terminal has a black screw, the other is silver. I've attached a picture of the 6-20P pigtail with the 5-20R. Do I just connect each of the remaining wires to the open terminals?

Yes, your wires from the plug are ground, hot, and hot. You connect the two wires to the hot (brass) and neutral (silver) on the 5-20R; order doesn't matter. Make sure strands are well twisted and all strands are in the terminal holes (no stray strands sticking out to short). Screw the terminals nice and tight.

If you had an ohmmeter, you could check connectivity from end-to-end, and make sure there are no shorts hot-hot-ground. Otherwise, plug in slowly the first time and yank it out if you see sparks!

 

[rmnelson]

Thanks @tga. Worked perfectly. It is now in my giant bag of adapters awaiting the next trip.

 

[TonyWilliams]

Otherwise, plug in slowly the first time and yank it out if you see sparks!

That is a joke, folks. Don't do this.

 

[tga]

That is a joke, folks. Don't do this.

Well yeah, but if you don't/can't ohm it out before plugging it in, you should at least be careful the first time.

Or maybe not build an adapter at all.