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I just bought a house in Mexico and was told they only wire for 120 service (two wires) to the meter.

I want to charge my Tesla which needs 240V at 40 amps (4 prong plug).

I have access to the meter and want to run two hot from the one hot at the meter and one neutral and ground to a new breaker box.

Will this give me the 240V 40amps I need to charge my Tesla?

nobody
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H Williams
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2 Answers2

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run two hot from the one hot at the meter

No, this will not give you 240V. It will give you 0V, because there will be no potential difference between the wires (because they both connect to the same point).

Your options are:

  • Talk to the utility and get them to supply you with two hots for 240V service.
  • Charge at 120V. You might be able to find an EVSE that will take a 30A 120V circuit as input, which would charge twice as fast as 15A/120V.
  • Step the 120V up to 240V with a transformer. This is pretty unlikely to be viable as you need to input 80A at 120V to get out 40A at 240V (both 9600W). You’ll need to figure out how big your service is (how many amps it can supply) and how much power the rest of your house uses to determine if you have the capacity to charge your car (you need to do this in the other cases too).
George Anderson
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nobody
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Electricity is not a cornucopia. In order to support a large load, you need the equipment to be in place to provide the capacity.

You need to start with a NEC Article 220 Load Calculation on your house, and ask the electric company what your service size is in amps. Divide the Load Calculation's VA figure by 120V to give the amps of service you need for that load.

Service Size - Load Calculation = amps to spare for EV charging

Breaker the EV circuit for that.

Fortunately, EV charging isn't overly concerned with voltage. The car knows how to charge at both 120V and 240V. Most likely, the Tesla Wall Connector will power up and work on 120V.

What's essential is communicating the correct charge current to the EV. You set that while Commissioning the Tesla Wall Connector.

Now if the Tesl Wall Connector won't accept 120V, then we can trick the little portable travel charger with a custom adapter cable and the correct dongle for your amps - NEMA 5-20 for 20A,

Obviously it will charge at half the speed using 120V instead of 240V. But this is your reality, unless you are willing to order a larger electric service from the utility.

If you're trying to do this with the portable travel EVSE, forget it, the best you can do is get the NEMA 5-20 dongle and charge at 16A (1920VA). That's weak tea.

I want to charge my Tesla which needs 240V at 40 amps (4 prong plug).

EVs don't need 240V. They can charge at a huge variety of amp currents. It's programmable.

You're trying to use the little travel charger, forget it, that's not gonna work. Get a Wall Connector.

I have access to the meter and want to run two hot from the one hot at the meter and one neutral and ground to a new breaker box.
Will this give me the 240V 40amps I need to charge my Tesla?

That would be an epic waste of money. You are better off spending that money paying for bigger electric service.

Harper - Reinstate Monica
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  • The Wall Connector [install manual](https://www.tesla.com/sites/default/files/support/charging/Gen3_WallConnector_Installation_Manual.pdf) claims it accepts only "Nominal 200-240 V AC single-phase". – nobody Aug 22 '22 at 02:03