Home charging help

Home charging help

I'd like to install my charging outlet outside but my electrician is saying this is not supported, is this true.

Also can you use an extension cord with the model S to charge. I this since the standard cord is not long enough to reach my car. It will be parked outside on my driveway.

Is PGE offering rebates for installation or is there a program to do the installation less expensive. My contractor is quoting $1000 to run the 240 outlet.

thanks for the help

Teoatawki | April 30, 2012

I'd like to install my charging outlet outside but my electrician is saying this is not supported, is this true.

Makes no sense to me. RV parks do it all the time. You'll need a 50 amp weatherproof box and outlet (or 30 amp if that's enough.)

Also can you use an extension cord with the model S to charge. I this since the standard cord is not long enough to reach my car. It will be parked outside on my driveway.

Extension cords are NOT recommended, and definitely not for everyday use. However, if you MUST, you should make a custom cord (or have someone do it for you) specifically to the length you require with wire gauged to carry the maximum current for a long time.

David den Boer | May 1, 2012

Or get a better electrician that is willing to work with you on setting up this charging station where the car will be. Bury the wire in conduit, and have it come up right where you need it.

BYT | May 1, 2012

Where there is a will and a competent electrician, there is a way!

Slindell | May 1, 2012
Schlermie | May 1, 2012

There used to be a 30% tax credit for consumer charge stations, but it expired at the end of 2011. Pluginamerica is trying to get it renewed. At the moment, I don't think California has a state tax credit for installing a charging station.

Thumper | May 1, 2012

I had my 50amp Nema 14-50 plug installed in Dec. to beat the tax credit deadline. My garage is full of shop equipment and we only park in the carport. There was no problem instlling in that location. The plug receptacle has a clear plastic hinged cover that can close over the plug while it is plugged in. Hope this helps.

Gator | May 1, 2012

Excellent post. My garage is a shop for my business so I want/need an outside outlet. The car will not be garage kept.

At a nearby office there is an outside outlet with two dedicated green EV parking spots. Only one plug though. Looks like the guys were drunk when they installed it.

Thumper, I am clueless on this part of Tesla. If I have a 40amp circuit available, can I use this for the car and run an external outlet? What does the Tesla require? 20, 30, 40amp? Do I need the charging station? Won't the outlet with recharging cord be sufficient?

Do Electricians know what is needed to be done. Or do I need to get them the specs?

Go Tesla, SpaceX and SolarCity.

Schlermie | May 2, 2012

I once saw someone post that a twin-charger vehicle should have a 100A line and a single-charger vehicle should have a 90A line. 100A for a twin-charger sounds about right, since 20kW at 220V needs about 90A and you probably want to add another 10% margin on top of that. I would expect you only need half of that (50A) for a single-charger though. I'm not sure where the 90A number came from for the single-charger.

Schlermie | May 2, 2012


No, you don't NEED the charging station unless you have some need to charge up to 60 miles in an hour with a twin-charger. Some people like the looks of it though.

Without twin-chargers and the charging station, your car will charge up to 30 miles in an hour at 40A, which is probably suitable for most folks if they're in the routine of charging overnight.

Even if you don't have a 220V outlet installed right away, you could probably get away with using a standard 120V outlet to cover your daily commute mileage for a period while you figure out what you want to install. (Unless of course, you have an exceptionally long commute.)

Thumper | May 2, 2012

Here is the link to Tesla's guide for electricians.

BruceR | May 2, 2012

@Thumper - The pdf you linked to is for the Roadster. Wrong powerlevels. Your electrician needs to know only the KW draw, voltage, desired connector and location. Wire size and circuit breaker rating are then easily calculated.
10kW standard charge - 120 or 240V connectors from 1 to 40A
20kW optional charger - Add on the second charger and the voltages are the same but the current doubles.
Model S comes with three standard connectors and others could be adapted/purchased if necessary.

Slindell | May 3, 2012

Model S Spec page states:

10 kW capable on-board charger with the following input compatibility: 85-265 V, 45-65 Hz, 1-40 A (Optional 20 kW capable Twin Chargers increases input compatibility to 80 A)

But I'm not sure how much to trust this until a production model comes off the factory line.

pilotSteve | May 8, 2012

Last weekend at the Bellevue Square Tesla store, one of the reps (who seemed to have good understanding of engineering details and who also is a service tech on the Roadster) told me the following about dual chargers:

(a) it should be easy to add the second charger after purchase if you needs change. He stated that the space is already there, just a matter of adding the charger.

(b) the Roadster has always had dual chargers (different specs but the purpose was to accept greater than 10kW). Tesla learned that many owners didn't have/use high charge current AC outlets so they decided to make dual charging an option in Model-S.

Both smart decisions IMO.

William9 | May 9, 2012

I just had the local electrical contractor by to quote on installing a 240V plug in my garage. He asked what amp circuit I'd like, and realized that I didn't really know, and find nothing in the official TMC stuff to provide guidance. My usual approach to things like this, is if a little's good, more's better. So I guess that means 40 amp service? When I mentioned that to the contractor he said he'd need to know the NEMA number for the proper receptacle. Again, nothing but generalities in the documentation. I did see a reference in one of the posts above to a "50amp Nema 14-50 plug". That correct? Saw another reference to a "dryer plug." Do those two relate?

Lastly, what is the functional difference between 20,30 or 40 amp service?


stevenmaifert | May 9, 2012

William9 - Here is a good article about dryer plugs: Most newer homes will have, at a minimum, a Nema 14-30 plug which is a four prong 220-240V receptacle with a 30 amp rating. If you already have one of these you could charge your Model S with it. The Nema 14-50 plug has the same pin configuration, but is rated to 50 amps and is common with electric ranges. The functional difference in amp service relates to how much electrical current can travel through the circuit before it becomes overloaded and trips the breaker. The more current, the less charging time, up to the maximum rating of the charger, which is 40 amps in a single charger Model S. This works well with a Nema 14-50 50 amp circuit as the working load is ~40 amps... A nice fit with the single charger Model S.

When consulting with your electrician, you also have to keep in mind the total service rating of the house and what other heavy draw appliances you have, such as electric range, central A/C, hot tub, pool pumps, electric dryer, etc. The main breaker in your power panel should have the service rating of the house stamped on it. Many older homes are only 100 amp service which could require an expensive upgrade for those planning to install the TM HPC.

Slindell | May 9, 2012

From Telsa Model S Spec web page:

10 kW capable on-board charger with the following input compatibility: 85-265 V, 45-65 Hz, 1-40 A (Optional 20 kW capable Twin Chargers increases input compatibility to 80 A)

Info on NEMA plugs:

Ohms.Law | May 9, 2012

@William9 and @Slindell - good advice. I'm sure this thread will serve as a convenient redirect in the future as more and more pay attention to their new car's power needs.

One decision I have to make is where in the garage to locate the 14-50 receptacle. If it is left of the car I will be forever getting out and stumbling over the coiled up cord. If it is in front of the car I will be running over the cord and snaking it out from underneath the vehicle. Coiling it from above seems totally impractical.

BYT | May 10, 2012

In less then a month the first signature Model S reservation holders will have their car and we will know for sure then.. :)

Brian H | May 10, 2012

Well, early June might be a bit hopeful; give it 5 weeks.

Soflauthor | May 14, 2012

As an update to an earlier post on installation costs, I installed a NEMA 14-50 outlet in my garage today with the help of an electrician who was moonlighting at $100 per hour. I used 45 feet of #6/4 power cable, conduit where required, a 50 amp breaker, a NEMA 14-50 receptacle, and miscellaneous other materials. Cost of materials was $168. Install cost was $300.00 for a grand total of $468.00. As an aside, material costs were much lower than I expected, and labor is about right for our market in SoFla.

jbunn | May 14, 2012

@ Ohm,

One of the other members proposed to make a swing arm that folded flat to the garage wall, and swings out to dangle the plug down to charging port height. I plan on doing one as well.

steven.maes | May 15, 2012

@ jbunn,

Very good idea. thx !

ddruz | May 15, 2012

Or we could just back in.

Brian H | May 15, 2012

make it easy; replace your driveway with a roundabout. :-O

Ohms.Law | May 15, 2012


Ohhhhh, I like that idea. And an engineering project as an added bonus. I'm on it!

Thanks for the idea from the original genius.

Schlermie | May 22, 2012

If you're having a new plug installed in your garage, you could have the plug installed in the ceiling so the cable dangles down from above the charge port. I don't know if the charge port is polarized or not. If not, you could even plug in the cable upside down, so the handle points to the ceiling.

dpann | May 25, 2012

SolarCity will install the twin charger for $1750 or $1500 if you get solar at the same time.

I got another solar company to give me a quote to install the 14-50 plug for $800 with an RV outlet housing.

DallasTxModelS | June 16, 2012

The new charging section under Model S gives you all the answers as well a solar option via partner Solar City.