Model S

Combining two 120V into a 240V connector

edited November -1 in Model S
I was wondering if someone more electrically inclined could figure out some type of device that would combine two 120V outlets and turn it into a 240V so that you could charge faster.

What I'm imagining is if I went to a friends house or somewhere that didn't have a high power charger. I could use 2 extension cords and plug in two 120V plugs into a small device that would combine it to make a 240V. The extension cords would have to be plugged into different breakers since most house breakers have a 15 amp capacity.

Is this possible?


  • edited November -1
    Yes, it is possible. It has been done. Check <a href=""></a>. The 2 circuits have to be on a different phase to make this work.

    I will let other more electrically savvy people explain the limitations of this device for charging your car.
  • edited November -1
    Biggest problem is making sure those plugs are on separate circuits, otherwise all you'll do it pop the houses breakers/fuses.
  • edited November -1
    It is fairly easy to determine if outlets are on different breakers just by looking at the panel. But without removing the cover on the panel it is much harder to determine if you are on different lines to be able to get 240.
  • EdGEdG
    edited November -1
    In the US, a house most likely has 220 volts coming in. Think of this as 3 wires: (1) stays at zero volts, or a "neutral" lead, (2) a "plus" 110 volt wire and (3) a "minus" 110 volt wire. I'm just using "plus" and "minus" for clarity for this discussion - every 1/60 second they're reversing, but ignore that.

    When you plug a device into a 110 volt outlet, that outlet is wired to the "neutral" lead and either the "plus" or "minus" lead, not both. The difference between the "minus" and "neutral" is 110 volts, and, because it's alternating current, you don't care whether it's a +110 volt difference or a -110 volts: it's the same difference of 110 volts.

    When you're using a 220 volt dryer, that plug has both the "plus" and "minus" wires, and the difference between them is, at peak, 220 volts.

    So, if you're plugging into two random outlets in a house, you might be getting a "plus" and a "minus" and you'll get 220 volts. Or you'll get two of the same, and the difference is zero, so you'll get nothing.

    These outlets are generally limited in current to less than what you should have for a car by the individual circuits they're on, too, so if you get lucky choosing outlets, you'll still be limited in the amount of power you'll get, but it will be twice what you'd get with one 110 volt plug.

    Needless to say, this ain't what you're supposed to be doing, and I'm not very knowledgeable on the varieties of problems you could encounter if you do this and are not lucky.
  • edited November -1
    Short answer: Yes, providing you have two separate circuits as stated above. The limiting factor would be the amount of current you can push through the extension cords without creating a heater. Most extension cords are 16 AWG or even 18AWG and are good for only a few amps at best. A nearby 110V circuit at 15A is better than two extension cords providing 220V at 6A. Tesla does not recommends the use of extension cords to charge.
  • edited November -1
    Its not just two circuts. As pointed out, its two different circuts on two different PHASES. Even if you find a seperate circut, you have a 50/50 shot at getting opposite phases.
  • edited July 2019
    Check this link for more detail:
  • So many misinformants here, trying to get you to buy something! Instead of telling you how to make it work! Guess what it will work! Like they said it has to be separate circuits! You’ll know if it isn’t! When it flips the breaker! Or GFI. Most houses also have a 220v either a stove, dryer or AC outlet! Use heavy gauge extensions cords for combining though! I ordered this just in case! A lot of hotels have outlets out side and are usually on a separate circuit/phase every 50 ft. Input power is automatically surge protected and balanced on Tesla charging. You could literally do three or four outlets and get more voltage and amps this way. Like a super charger. But you have to worry about people tripping on cords, water submersion and electrocution. So the more you do this way the more unsafe it gets. Just sayin. Kids do crazy shit!
  • Here’s the combiner Parkworld 885545 Combiner, RV Splitter V Adapter Cord 5-15P & TT-30P male to 14-50R female
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