How to wire the garage...question for the electrical engineers in the crowd...

You only need more than 50A if you're planning on installing an HPC which would be hard wired. Other than being cool and convenient, the HPC is a bit overkill.

install a large diameter conduit back to the distribution/breaker box. you can decide later what to run through it. minimum size for the recommended HPC 4-gauge wires is 1" conduit. i would go with larger than that (2" maybe? more even?) to allow for flexibility. make sure you have extra space in your box for additional/new breakers.

make sure the electrician understands this wiring is to deliver 40amps for hours. No getting away with badly crimped spots getting hot after a few minutes, but settle down after you're finished boiling tea water.

Any electrician can install a 50A circuit. It's the same as most kitchen range outlets. 3 x 6-gauge wires, ground the box, and you're done. You only need conduit if it's exposed.

Run Cat6 or Cat5e network cable or give yourself the ability to pull it afterwards. You should be adding it to any remodeled parts of the house anyway.

Why would you risk doing this yourself when there's a tax credit to have it installed by a professional. I wouldn't skimp on the charger after I just paid $57k+ out of pocket for a car.

You might end up like the volt owners and have a burnt car because of faulty charger wiring.

1. Who said anything about doing it themselves?
2. The tax credit is only for chargers installed this year, so not applicable.
3. The "faulty wiring" was plugging the Volt into a three-way adapter plugged into an overloaded 110v outlet.

All that said, I'll be doing mine myself because I know what I'm doing and I'd rather save the money for more important things like paying off the car.

See also this near identical thread: How to design my garage?

May merge later.

Mycroft, When I read the IRS form 8911 for this year, it looks like a tax credit for any charging infrastructure will qualify. How have you determined it does not? I'm not really challenging you, I am getting my 50amp circuit on Monday and had hoped to get a partial credit by beating the end of the year. http://www.irs.gov/pub/irs-prior/f8911--2011.pdf

Feel free to claim it Thumper.

My view, (and I haven't checked with an accountant or the IRS - even if I had, the IRS is known to give out conflicting information), anyway, my view is that since I don't currently have an EV, I can't claim to have placed the 50v outlet "in service".

Now, if you install the outlet on the exterior of the garage and have proper signage that the outlet is available to any EV for charging, then you might honestly claim that it's "in service".

Mycroft said:

Now, if you install the outlet on the exterior of the garage and have proper signage that the outlet is available to any EV for charging, then you might honestly claim that it's "in service".

Click to expand...

Or invite a Roadster owner over; in my uninformed opinion, once it has charged any EV, it is in service.

I see your point. I'm a much more favorable interpreter of the text than you. If the outlet is hot and could be used it is in service as far as I'm concerned and that's the way I expect to defend it to the IRS. I'll sign up on PlugShare. Then it is truly in service and advertised on the internet.What do you think?

Sounds like a good plan to me. The odds of getting audited are fairly slim anyway and I've been told that it's best to claim every deduction no matter how tenuous. If by chance you're audited and they toss a few of them, then you just pay the taxes you would have owed anyway plus a small penalty. It's not like we're trying to claim a million dollar tax exempt trust or something.

Just did the wiring recently- it's really easy
Get size #6 wire
50 A, 220 V breaker

Step 1: turn off the main breaker
Step 2: Install the breaker ( make sure you get one that fits)
Step 3: Install the wire fish it through the wall
Step 4: Install the circuit
Step 5: Install the outlet (pending the Tesla's info for plug)

It's relatively easy, but then again, I'm an engineer, but it shouldn't take more than 1 hr to do for a normal person to do. Honestly, epoxying the floor was more time consuming the putting the circuit

Late to this party. Would have run heavier gauge wire from the main panel to a 100 Amp sub-panel in the garage. Start with your 50 Amp charging connection. It's easy to later install additional charge points or other equipment. Also, in many areas electrical code requires a cut-off switch near the car charger. A visible breaker panel satisfies the requirement.

Undergraduate Engineering degree, but I'm not up on local code & permits. Had a Tesla-recommended electrician plan out the installation. We ended up with 2/3 copper "Romex" from ganged 100 Amp breakers in the main panel to a sub-panel in the mud room, next to the driveway. The sub-panel has ganged 100 Amp breakers for a 2/3 copper cable running to an HPWC on mudroom exterior wall. When you stand at the HPWC, the sub-panel is visible through the glass panes in the door. Also had the electrician run shielded twisted pair (STP) from a cable reel above the mudroom ceiling to the HPWC. Got a permit without a problem, inspection was a breeze.

We ended up with such heavy gauge because of long run from main panel on the far side of house from the mudroom and driveway. Engineering experience has repeatedly shown that over-capacity frequently turns into necessary capacity. Just about as much labor to run 2/3 cable as it would have been for 3/2, Tesla's minimum. Our main panel could support the 240 Volt / 100 Amp addition.

Now we're future-ready. Not the same as future-proof. Just as "executive-ready" technology - easily used by someone who doesn't want to waste more than 10 seconds on training - is not necessarily "idiot-proof."

Want to add a 50-Amp outlet to charge your electric Smart car? Configure the HPWC for 50-Amp service, Convert the HPWC breaker to 50 Amps. Add a second 50-Amp breaker for the new outlet. Run a cable the short distance from the driveway to the sub-panel.

Want to add a second HPWC? Run its cable back to the sub-panel to share the HPWC breaker. Then run the STP from the existing HPWC to the second one. Configure the HPWCs to share the circuit.

If you are thinking about a possible second electric car, i also would go with the 100 Amp feed to the garage (assuming your service is up to it). Power one hpwc now, with an easy upgrade later to two. The hpwc’s will share the available power. I did this to also have one inside and one outside charging position