220 volts from double 110 volt circuits

220 volts from double 110 volt circuits

I know this has been mentioned before, but I thought I would share how well this worked. I made an adapter for double 110 circuits to serve as a single 220. Using a normal 110 circuit, I charge at a rate of about 4-5 mi/hr. My adapter has a meter built in to help identify the individual circuits from opposing buses. Each circuit was supplied by a 20 amp breaker with 12-2 cable, and no additional loads were on the circuits. I was able to charge at 16-17 amps (80% of a 20 amp circuit). I gained 12 mi/hr. Definitely worth the effort.

Mark K | May 27, 2013

So you identified outlets from each leg (above and below earth ground) and stacked them for 220V at 20 amps?

ajamison | May 27, 2013

That sounds like a fire risk to me but I assume if you did it then you must have at least done enough research to do it safely

shop | May 27, 2013

Yes this will work. You must find two 20A 120V outlets that are not only of different breakers, but breakers that are on different 240V legs. You then connect these two outlets to something like a NEMA 14-50 receptacle, and plug in your UMC with the 14-50 adapter into your box. YOU MUST MAKE SURE TO DIAL DOWN YOUR TESLA TO ONLY DRAW 16A!!!! The original poster forgot to mention that part (ahem).

You can also buy a box ready made to do this:

DouglasR | May 27, 2013

How common is it that the two 110 outlets will be differently phased, yet close enough together that your adapter can reach them?

shs | May 27, 2013

In the steam-brite blurb above, it seems the guy demoing it has both 110V legs of the device plugged into the same duplex receptacle. The chances of both outlets on the same duplex receptacle being on a different breaker and different phase is practically zero.

The idea is a good one, but that blurb makes me suspicious of that implementation.

shop | May 27, 2013

Yes, the implementation seems OK (I like the features), but the instructions and marketing leave a bit to be desired. The product though comes with two 25' cords meaning the plugs could be 50' apart. Modern kitchens are wired with more than one circuit. And you have dedicated circuits for garbage disposals, central vacs, trash compactors, etc. So finding two separate 20A circuits in a home isn't too hard. For safety's sake, you really should verify that the circuits are actually connected to 20A breakers rather than 15A ones. Flippng the breaker to see if the circuit deenergises is good idea to find the correct breaker.

David Trushin | May 27, 2013

Seems like a lot of work to go thru when a nema 14-50 combines 2 out of phase 110's anyway.

Lush1 | May 27, 2013

Before going to the trouble, make sure your breaker box has 2 legs. Not all do. My mother in law has electrical service with only one leg, so there is no way to pull 240 volts out of 2 outlets in her small house. I was considering this idea to charge my Model S when we visited her. A neighbor who has an identical house told her that it wouldn't work. I was skeptical, but when I checked the breaker box I found that indeed, it had only one leg.