Any experience with 120v 20amp NEMA 5-20 outlet for charging?

Any experience with 120v 20amp NEMA 5-20 outlet for charging?

It turns out that with our detached garage, running a new electric line from the electric panel would involve challenging and substantial trenching. I'm looking into the alternative of a slight upgrade to the 120v system already in the garage. Our electrician says he could easily upgrade us to a 20 amp NEMA 5-20 outlet.

Does anyone have real-world experience with this type of outlet? I'm especially interested in your charging rate. The Tesla material says about 4 miles per hour, but I've read forums elsewhere suggesting people are getting charging rates higher than that.

I think in my situation I could probably make this work with the occasional top-off at a supercharger when I'm planning a longer trip.

Temple07 | 6 settembre 2018

with my 120V I was drawing around 12A and was able to get max 4 miles/hour. So it calculated it would take about 12 hours to bring it from 218 miles to 275 miles. When plug into 240V at 32A, I get about 29 miles/hour. So that is about 1 hour 50 min to charge from 218 miles to 275 miles.

Hope that helps. 20 Amp might charge faster, but I doubt that much more.

Hughesjo | 6 settembre 2018

Really depends on how much you drive. I get about 6 miles per hour on my 5-20 but my daily commute is only about 10 miles and I have free chargepoints at my office that I use to top up occasionally. I’ve had the car since early June but only have 2500 miles on it so I’ve not had any problems. I’m in the SF Bay Area with lots of superchargers too but I’ve never actually used them except for once just to try it out.

So it works for me however I still will eventually upgrade to a 14-50 for even greater convenience. When I have had some heavy consecutive driving days I’ve had to think about managing the SOC and it would be nice to not even worry about it.

zippy | 6 settembre 2018

i use this outlet at home. even with an extension cord (rated for the load) i get 6 miles of range per hour. 60 miles overnight is more than enough for my driving, and i usually only plug in two to four times a week.

socalbtc3 | 6 settembre 2018

I am getting 4mi/hr too plugged into the garage normal 5-15. With a 48 mile round trip commute for my wife and scheduling charging to begin at super off peak times, we do not have enough hours before she leaves the house at 6am to get to our 80% target each night. But we make it work by alternating cars since my commute is 24 miles. So by time we get to the weekend we are about 180 miles remaining which is plenty and we have the entire weekend to get it back to 80% working around super off peak rates.

However, tomorrow we get our wall charger installed on a 60 amp dedicated circuit so the above dance is no longer necessary but it could have worked for us long term.

Alex_SD | 6 settembre 2018

Yes, I use it all the time. You need to purchase the 5-20 adapter from Tesla. It’s $35. I usually get 6 mph charging speed.

zippy | 6 settembre 2018

what alex said - 6 miles per hour with the adaptor.

kcheng | 6 settembre 2018

Is there no way to turn it into a 240V NEMA 6-20?

SactoEVer | 6 settembre 2018

Re turning an existing 120 to a 240 without running a new cable/conduit .. my electrician said that wouldn't be allowed under the code .. does someone who knows this stuff think I should get a second opinion?

Coastal Cruiser. | 6 settembre 2018

SactoEVer, it is a bit surprising that your electrician specifically said new cable. The idea behind the 6-20 trick (240v @ 20Amps) is that it does NOT require a large diameter (lower gauge) wire, because the current flow is about the same. What it does require is for their to be room enough in the panel to add a second breaker, as the 220V config requires two breakers... which usually means a spare (adjacent) slot be available.

So yes, it might be worth getting that second opinion.

jjgunn | 6 settembre 2018

Find a 2nd 20A outlet on a different breaker (non-GFI) & use this.

You'll get 15-20 MPH (~230-240v @ 16A) - it works well!

johnse | 6 settembre 2018

That 2nd outlet needs to also be on the opposite phase, not just a separate circuit.

johnse | 6 settembre 2018


As @Coastal Cruiser said, there shouldn’t be an issue with the wiring. Both the 5-20 and 6-20 are three-wire circuits with one of them being ground. The only difference is that the 5-20 has one hot (black) and one neutral wire (white). The 6-20 has two hot (2 black or black/red). In re-purposing it, the electrician simply needs to mark the neutral as hot by wrapping it with black tape.

The other issue might be if there are more than one outlet on the circuit. You would need to change all of them to 6-20, but I do not know if it would be OK to have multiple outlets on the 240v line. Otherwise, probably need to remove extras and add cover plates.

Atoms | 6 settembre 2018

You can install a 6-20 socket in place of the 5-20. Put in a double pole 20A breaker. If you need more space, you can likely put in tandem breakers. The white wire can be wrapped in red tape on both ends to indicate it is a 240V line. Really quite easy. You can order breakers from Home Depot online for most panels.

Coastal Cruiser. | 6 settembre 2018

johnse, +1. SactoEVer, if more than 1 outlet is on that line, that might explain why the electrician put the kybosh on doing the conversion. Let us know what you find out.

johnse | 7 settembre 2018

One other thing that may not allow that conversion. One somewhat recent code requirement is a certain maximum spacing between outlets. Not sure that applies in the garage, but it might not be permissible to remove outlets if that means not enough outlets are then available.

SactoEVer | 7 settembre 2018

Thank you all .. this is VERY helpful and shows why this forum is so valuable. There are indeed two circuits into the garage .. one for garage door openers and one for all other outlets/lights. I need to do some calculations to see if the garage door openers can be put on the lights/plugs circuit without challenging the load.

michiels.evan | 17 settembre 2019

Check out my youtube video on this. It works great!

jimglas | 17 settembre 2019
andy.connor.e | 17 settembre 2019

Going to Six FLAGS

rjriker | 18 settembre 2019

I do not know your situation, but if trenching is not an option and that is due to concrete or an asphalt driveway, you might ask about someone boring underneath. Not sure that works, and it that area includes water or electric lines that may not be an option. Just an idea.

vincelorto | 18 settembre 2019

rjriker+1. I'd explore trenching or boring. not as hard as you think but if it's far, the cost of buying the right copper will be expensive.