I thought I would make a new post with pictures I took while building my NEMA 6-20P to NEMA 5-20R Adapter. This adapter allows you to charge at 12A or 16A at 240V from a NEMA 6-20 receptacle. The NEMA 6-20 receptacle is easy to install if you have an existing 120V outlet on its own dedicated circuit, with 12 gauge, 3 conductor wire. You just change the breaker in your box to a 240V breaker, move the neutral to the second hot and then swap out the 120V receptacle for a 240V, NEMA 6-20 receptacle. If that is confusing, ask your electrician for help.
The benefit is you go from charging at 3-4 MPH to charging at 8 MPH @ 12A or 11 MPH @ 16A. If you are fine charging at 8 MPH, stop here and go buy the Tesla NEMA 6-15 adapter (Tesla — NEMA 6-15) and you can avoid building this. If you want 16A charging, you'll need the Tesla NEMA 5-20 adapter (Tesla — NEMA 5-20) as well.
The upside is you can almost always charge the car overnight (depending on your usage), and you get 90+% efficient charging from 240V, vs ~70% efficient charging from 120V.
Parts:
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
But, given the trouble I had assembling this, I would recommend getting a slightly longer (3ft) cable instead for a few dollars more:
Amazon.com: NEMA 6-20P to C19 Power Cord - 3 Foot, 20A/250V, 12/3 AWG - Iron Box # IBX-4937-03: 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
Steps:
The benefit is you go from charging at 3-4 MPH to charging at 8 MPH @ 12A or 11 MPH @ 16A. If you are fine charging at 8 MPH, stop here and go buy the Tesla NEMA 6-15 adapter (Tesla — NEMA 6-15) and you can avoid building this. If you want 16A charging, you'll need the Tesla NEMA 5-20 adapter (Tesla — NEMA 5-20) as well.
The upside is you can almost always charge the car overnight (depending on your usage), and you get 90+% efficient charging from 240V, vs ~70% efficient charging from 120V.
Parts:
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
But, given the trouble I had assembling this, I would recommend getting a slightly longer (3ft) cable instead for a few dollars more:
Amazon.com: NEMA 6-20P to C19 Power Cord - 3 Foot, 20A/250V, 12/3 AWG - Iron Box # IBX-4937-03: 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
Steps:
- Lay out all the tools you need. I would recommend a different wire stripper. My automatic wire stripper did not work so well for this. View media item 116576
- Cut off the C19 end of the cable. It is not needed. View media item 116577
- Follow the instructions provided to attach the NEMA 5-20 receptacle to the wire. I found that I needed to remove the extra insert in the cable clamp, since the cable was larger than the guide size. View media item 116578
- Carefully strip off the outer insulation using a razor or another tool. Be careful not to damage or knick the insulation of the wires within. This was the hard part. I messed this up several times and had to strip farther and farther back, which made my adapter shorter than I originally planned for in the end. In retrospect, I'd recommend starting with the 3 ft or longer cable so that you have more core to work with when you invariably mess up. View media item 116579
- Strip the inner conductors as shown in the receptacle instructions. If you mess up here, just start over at step 4 and strip back more of the outer jacket... If I did it over again, I would recommend leaving about 3/16" more of the insulated wires exposed than the instructions recommended. The bare copper length was good. It was very difficult to get the wires into their respective sockets with the wires stripped as recommended. A bit more length of the insulated portion of the wire would make it easier. Just make sure to not expose too much. The cable clamp needs to clamp down on the outer jacket, not the inner wires. View media item 116580
- Assemble the plug. The only important connection is GREEN to the ground terminal (GREEN). Both the white and black wires will be hot, so they are interchangeable. Be sure to slip the cover over the wire before starting the assembly. View media item 116581View media item 116582
- Check to make sure all the wires are inside the screw terminals and there are no flyaways (bare strands) protruding out of the wire guides. View media item 116583
- Screw on the cover and tighten the cable clamp down on the wire jacket. View media item 116584View media item 116585
- Be sure to label your adapter: "Warning 240V: TESLA Charging ONLY!". Plugging a normal device into this adapter might cause damage, so it is good to warn people.