Lack of Search/Inverter Question

First, let me apologize if this topic has been covered, but I can't find a way to search within the forum to check. I'm sure if my question appeared before, one of the regulars will let me know. Now, here's my idea/question/bone-headed scheme: I have a 110 outlet at my office which is right next to my parking spot. I would tell you that it's a coincidence, but an electrician who works on Sunday when the office is closed might call me a liar. This is great, as I'm in the office for 10 hours/day, but I only get about 30 miles of charge, as opposed to a full charge if the outlet was 220. That being said, it dawned on me that with an inverter for about $50.00, I could change this outlet to a 220V. power source. The circuit operates our security gate so it's important that I don't blow the breaker and put an end to my convenient (not to mention free) charging. My guess is that since the gate is run by a powerful motor the breaker has to be at least 30 amps. I can set the car to accept 24 amps (thanks jat) and be just fine as long as it doesn't hurt the car. So two questions: 1) Will it hurt the car? 2)Does the plug end adapter have anything to do with the power provided. Some of the 220 inverters look like they have an ordinary three prong plug. If I use the standart 110V plug end and the outlet gives 220V will I get the 220? This seems like a great, cheap solution. Someone once said, "For every problem there is a solution that is quick, easy, logical and WRONG!" It seems that this is the first three, but I'm very not sure about the wrong part.

First of all, an inverter takes DC current and produce AC current, so that isn't what you are talking about. To get a higher AC voltage from a lower AC voltage, you need a step up transformer. But when you do that, you lose power in the conversion and you get half the amps (assuming 100% efficiency). Also, a standard 15A 120V outlet, one that does not have a right angled blade on one of the blades, probably will have 15A wire and/or a 15A breaker. No electrician would protect a 120V outlet with a 30A breaker, that would be bad. My gate uses a 15A breaker, 120V, so no need for a bigger breaker. FInally, if your 120V plug is sharing the breaker with the gate motor, you might have trouble. The gate motor may draw a good amount of the circuits current when operating, and the Tesla will draw 12A continuous, so both loads together may trip the breaker.

Shop: Thanks for the reply. You're completely right I meant a step up transformer. I think I can check the breaker on the gate. So far, I've kept the car plugged in all day and the gate and the charging seem to be fine. If I use a step up transformer and set the car to 10 amps wouldn't I still charge substantially faster and be safe? If I could get 10 miles/hour of charge I'd be thrilled. My commute is 20 miles round trip so I'd net 60 miles a day positive.

I'm trying to economically justify buying the car and the biggest justification is that I save $500/month in gas. The more free electricity I get, the better the justification. Fortunately, since I've had the car for three weeks, I don't need any justification. It's worth the price, it's great to drive and even if it cost more to fill it with electrons than gas, it's worth it. There are somethings that are more than worth the price and this is it. But if I can lower the price, I'm not averse to doing it.

I'm sorry, I don't know much about electricity (or to listen to some people, about much of anything else) but when the car is charging, what is the relationship of the Amps to the Volts. Can I have 220V with 12 Amps? If so, what is the difference in charging rate between 12 Amps and 24 Amps. Would I charge faster with 110 at 30 Amps that with 220 at 15 or would it be equal?

They say a little knowledge is a dangerous thing and I'm a very dangerous man.

The power the car draws is equal to the amps multiplied by the voltage. A step up transformer would give you double the voltage, but half the amps, so you would be left in the exact same position minus conversion losses. If you tried to draw 15a at 220v through a step up transformer, the 110v end would see a draw of 30a, and that would trip,the breaker. No, the only way to get more power to the car is to plug into the panel and draw 220 or 240 volts right from the start.

Technically those are equal but I doubt you will get 30amps with 110.

"Would I charge faster with 110 at 30 Amps that with 220 at 15 or would it be equal?"

It would be equal.

Thanks, I guess I'm back to finding another circuit to pull a wire into my 110 outlet and convert it to 220. You have saved me money and disappointment. Another great idea dashed. It seemed so easy, quick and simple----and wrong.

If you have control over the outlet and breaker panel, you can actually just convert the outlet to 220V without the neutral (reusing the existing neutral wire as a hot wire on the other phase after marketing it as such). An electrician can easily do this and you would get 240V at whatever current the wires are rated for, and choose an appropriate outlet and adapter to go to the 14-50.

Yeah, but it sounds like the circuit is being shared by the 120V gate motor, so that wouldn't work. Good idea though!

I have a similar question, where I work there are two
Rows of 110 outlets for block heaters with a beaker
Panel in the center so I'm assuming each side is on
A separate 15-20 amp breaker . So would it b possible
To wire two 110 plugins to a 220 outlet and get 15
Amps at 220?

Yes, if each outlet came from a different "side" of the electrical panel. You could check this if you could stretch a voltmeter between the two hots of the plugs. The hot side of a 120v plug is the right most one or the one with a shorter blade if the socket is upside down (usually ground bottom, left neutral, right hot). If the voltmeter showed 240v or so, then there is your 240v, with an appropriate adapter.

The other thing to check for in 120v sockets is whether the receptacle is actually a 20a receptacle or not. Most receptacles are 15a, but in some garages and commercial settings, I have seen 20a receptacles. The difference is that a 20a receptacle has a horizontal notch on the neutral blade (left one is ground is on the bottom). If you have a 20a receptacle, then you can make your own adapter (until tesla makes one) and charge at 16a instead of 12a. 33% more power.

It would be great to have others share how they tackle:
1. Charge at work ideas and solutions.
2. Tesla friendly work places.
3. Charge on trip ideas and solutions.
4. Tesla friendly Hotels.

PS Tesla include search function for the forum /blogs thanks.

Thanks for the info. it's nice to have a knowledgeable
Person to run this by before I electrocute myself !

@chadrchristensen79 - the product you want is quick220, but the outlets have to be on separate phases.

By separate phases, u mean separate breakers?

@chadrchristensen79 - No. Typical service in the US is 240V split-phase wiring, which means you have two hot lines that are 180 degrees out of phase with each other and are 240V between them, and are each 120V with respect to ground. So, your main panel will have two lines coming in that go to alternating breaker slots. A 240V breaker actually connects to two adjacent slots, so you get both phases. If you happen to have two 120V circuits that are on the different phases, you can get 240V between the hot lines of those two circuits, and using a device like the quick220 or making your own adapter you can generate a 240V circuit. Note that unlike a 240V circuit, you do not have a common breaker, so if one breaker trips the other one may not, so the 240V outlet at the end of your adapter might still be partially energized when you flip only one breaker. If the two outlets are on the same phase, both hot lines are wired to the same place and therefore you get 0V between them.

There are also 3-phase systems, in which case you are getting 208V between two phases that are 120 degrees apart. They can be wye-wired or delta-wired (which determines where neutral is with respect to the phases), but those are generally used in commercial or large residential buildings. The same thing works there, but you get 208V rather than 240V between any two phases (if you also need neutral, things get much trickier here though).

Can I test this by doing what@shop said earlier and
Stretch a volt meter between the two outlets?

Well, I think so :-)

Just be careful if your voltmeter probe wires aren't long enough and you jury-rig extensions - remember that you are running 120V now on those wires, want to make sure the connection points are insulated so they don't accidentally touch something/anything.

You can start your test by putting the probe wires into one socket - one in the left blade, one in the right blade, and you should see 110V to 120V. Make sure the voltmeter is set to AC volts in correct range for the expected voltage.

Thanks a lot for the detailed explanation I really
Appreciate it. I've done some wiring but don't know
Anything about the fundamentals. Thanks again !


To answer your first question, you can do a search via google and specifying this site as the target, or use

For the electric questions, you heard from @jat and @shop on how a transformer works. The fundamental reason your idea is impossible is because of conservation of energy. If you could do what you suggest, you could keep stepping up voltage and drawing the same current, thus generating an infinite amount of energy from any outlet. So that's the simple explanation of the "wrong" part from your nice quote.

The "quick220" method will work, but has some safety and logistical caveats discussed in several other threads and on TMC.

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