Electrician's advice? I need help!

[14Accent]

So, as some of you may know I recently bought a 2013 Chevrolet Volt. I'm loving it so far! As of now, I've exclusively used the 120v charger that comes with the car, which is limited to a max of 12A charge rate.

In doing research about adding a 240v circuit to my garage, I realized that it (appears) to already be set up for 240, although there are no 240v outlets installed. Here's the setup:

The house is OLD, 1905. However, all of the wiring has been redone. The garage is about 5 years old, and has a master disconnect switch mounted where I assume the power comes in from the house. The wires are buried. I have yet to remove the drywall surrounding the disconnect, however the garage is fed by a 2-pole 20A breaker in the main panel. The wires running to the garage are I believe either 10/3 or 12/3, there's a red wire connected to one half of the breaker, black to the other, white to neutral and ground to, well obviously.

Question is, before I go tearing out drywall, how might this be wired in the garage, seeing is everything in/on/around it is nothing but 120v. Did they run wire, possibly expecting to add 240 in the future, and just leave the red wire capped in the wall? If this turns out to be the case, is it as simple as adding a 6-20 240v outlet post-disconnect with the appropriate wiring and receptacle? I can handle simple wiring, not shocking myself is easy, I just don't want to budget for a $200 charger if I'm chasing a futile project.

Thanks everyone!

 

[Kage860]

I imagine you’re not supposed to just tap off an existing 240 line for a car charger, the right way to do it is to put a new 240v breaker in the main electrical panel and run a new line to the charger.

 

[14Accent]

Originally Posted By: Kage860
I imagine you’re not supposed to just tap off an existing 240 line for a car charger, the right way to do it is to put a new 240v breaker in the main electrical panel and run a new line to the charger.


Not for one of the larger units, no. Those draw up to 40A and require a dedicated circuit with a breaker. I plan on using a 240v 16A charge cord, the maximum charge rate the car draws is 15A. A 20A circuit should be plenty for the car, the motion light outside, and the garage door opener I would think. But again, I'm no electrician. I know just enough to get me zapped.

 

[earlyre]

unfortunately my eyes kinda glazed over in paragraph 2, but Yes, your Volt will take a level 2 (220v)charger.
My brother bought a 2014 Volt last summer, and he has recently done this project, including modifying a charger.(possibly a Leaf charger?) He can now get a full Charge overnight,vs 14 or so hrs.

I Know he has Bought/Sold a few EV Chargers on Ebay the last few months...

 

[Kage860]

20 amps is not much. You’re not on the right track.

 

[PimTac]

Sounds like you need a electrician friend just to check it out for you.

Years ago I had a garage built and asked for a 240 circuit. They installed the breaker panel and ran a short wire down into a junction box and it was covered. That way it would be easy to wire up whatever I wanted.

 

[EdwardC]

I spent a lot of time looking into this since we bought a Leaf last year.

It sounds like you're doing well with what you've said.

Home AC power is usually 240VAC, with the neutral line in the middle. So if you measured red to neutral, you'd get 120. Black to neutral, you get 120 again. Measure black to red and you should get 240.

You should be able to wire in a 240 outlet, but you probably should be careful to use a proper amperage outlet (20a). You'll need to match your charging cable (EVSE) to your new outlet. I don't think that it would strictly be to code to add an outlet like that that isn't a dedicated run.

One other option, which has it's own risks, is to find the two outlets in the garage that are on opposite legs (red and black), then make your own dongle that joins them back together for your new EVSE.

The thing is, odds are likely that your entire garage is fed by that same feed, so you may pop breakers if you, say, opened the garage door while the car was charging.

I do think that it's worth doing though and that you're on the right track. I have read, at least with the Leaf, that charging at 240v is much more efficient than at 120v, even at the same wattage (there's more loss converting 120VAC to the ~400vdc of the battery than from 240VAC).

I purchased one of the Chinese EVSEs that will do up to 240v, 32a. It is adjustable down to 6A, and with a bunch of RV dongles, I can charge many more places.

Good luck!

 

[Sunnyinhollister]

I'm pretty sure the Volt is only capable of charging at 3.3kW so you do not need a 40A service.

Here's one - and its made in America:

https://store.clippercreek.com/index.php...3832.1521862162

 

[DerbyDave]

When I had my LEAF I had a 50 amp sub panel installed in my garage that was fed by 3 Conductor #6 wire. In the sub panel I had a 40 amp breaker for my charger. The car could pull 6.6 kW while charging using the Level 2 charger I had. I am pretty confident in my wiring skills, (I wired my entire basement) but for this project even I consulted an electrician. Screw up and you could start a house fire!

 

[14Accent]

Originally Posted By: DerbyDave
When I had my LEAF I had a 50 amp sub panel installed in my garage that was fed by 3 Conductor #6 wire. In the sub panel I had a 40 amp breaker for my charger. The car could pull 6.6 kW while charging using the Level 2 charger I had. I am pretty confident in my wiring skills, (I wired my entire basement) but for this project even I consulted an electrician. Screw up and you could start a house fire!


That makes sense. If I was pulling that kind of current, I would too. This is a fairly standard 20A circuit, the Volt only pulls 3.3kw as stated. So around 15A. I'm quite sure the existing wiring can handle it. The car is the only thing in the garage that's drawing any significant power. I've been charging at 12A through the 120v charger that comes with the car and all is well. At 240v, max charge rate of 3.3kw equals 13.75A.

 

[Delta]

Sounds like they used a shared neutral for the power in your garage. More than likely one hot to run the lights, and the other to the receptacles. Do not tap into this, you will need to run a new line for your charger.

 

[BrocLuno]

Yup, what he said ^ ...

You need to upgrade what is there now. Best to have it sorted by an electrician, or a buddy who knows what he's doing ...

The existing circuit can handle casual loads, lights, GDoor opener, etc. But should not be pressed into service for a dedicated draw like car charging.

Need to know how how big conduit is between house and garage. May pull out existing wire and pull in larger, sub-panel, in-garage breakers, etc.

 

[Donald]

They ran two 120v circuits using a common neutral which is fine as each 120v circuit is on a different leg of the 240v.

 

[bullwinkle]

If it's running off a double 20A breaker (tied together in your panel), and you're running a 16A rated charger, you could run it-but NOTHING else in your garage at the same time! You would be better off running a dedicated circuit, or a bigger cable (like 50 amps/6 gauge or bigger) so that you could run other stuff at the same time. Good news is-a battery charger is a resistive load, you're not starting motors or anything, so you're not going to have big inrush current problems.

 

[Linctex]

Originally Posted By: EdwardC
One other option, which has it's own risks, is to find the two outlets in the garage that are on opposite legs (red and black), then make your own dongle that joins them back together

Originally Posted By: Donald
They ran two 120v circuits using a common neutral which is fine as each 120v circuit is on a different leg of the 240v.


I shamefully admit I have done this when I needed 240v (temporarily) to run a 240v welder.

It worked just fine.

 

[14Accent]

Thanks guys. Looks like a call to an electrician is in my future!