Join The Community

Extension cords

I have read somewhere that extension cords to the Tesla Charger aren't allowed, or at least not recommended.

There is one thing in Sweden: the Arlanda Airport has free parking and charging for EV:s. So far, so good.
But, yesterday, when I should take advantage of that, the huge Tesla contact, made even more huge by the additional contact for European outlets, didn't fit into the cupbord at the airport with the outlet. It is simply too large.

So it will be very touch and go for me to get home later today, when I land. If the vampires have been there, I will have to beg a MacDonald or something for a bit of electricity. Why is everything happening to me.....

This could be solved with a short extension. Next time, that is. But is one allowed, I wonder.


Norwegian Tesla-owners have run into the same problem. The UMC-plug won't fit in any of the public charging stations in Oslo.
This short cable from Clas Ohlsson one is a popular workaround:

If your extension cord is too long/thin/coiled up you can run into serious problems (like fire), but I have no qualms about running a 35m extension cord from my mountain cabin to where I will park the car, to charge at 220V/10A.

...and in answer to your actual question: No. The manual explicitly states that you can not use an extension cord.

I (and other Tesla friends) have used extension cords on many occasions and had no problems.

There are a couple of very informative threads on this topic. Official policy in owner's manual is do not use extension cord, but in practicality it is safe if done properly. I've used a 110V 15A extension cord on many occasions without problems.

If you want to be safe,try plugging it in with the extension cord when you get home, wait 30 mins-1 hour, and check for a hot cord anywhere along the line. If there is, either try a new extension cord or just buy that short cable. You might not have to wait 30 with the high voltages to be able to tell- but the point is, try it, and see if the cable begins to heat up/

There should be no "scientific" reason we can't use an extension cord, but I imagine the following conversation:

Elon - "It's a simple calculation of the guage of the wire, the length of the cord, and the amperage flowing through the wire!"

Elon's Lawyer - "Dude, we're talking about Americans here! Americans don't know nothin' 'bout no math! Americans know how to break stuff, and how to sue over every little thing. NO EXTENSION CORDS!!!"

+1 MacDaddyDude, LOL

I just saw this on another thread here, right at about 2min 20secs, it looks like the Tesla employee hooks up the UMC to an extension, unless I'm mistaken?

I did a quick search for extension cords on Home Depot. The first one I looked at (I was picky) said "Maximum Amperage: 10A." Hook your MS up to that at 15 amps and it will melt.

I imagine this is why Tesla says not to use an extension cord.


@redacted - IMO a responsible company wouldn't even make a 100' extention cord with a wire gauge of 16. Hooking that to a Tesla is asking for trouble.

Bigger wire, shorter cord, more money:

And even then, I would restrict the Tesla to only pull 10 amps. (and that's with zombies in front of my house banging on the garage door) :)

Thanks, everyone.

I did get home, by driving egg-shelly and VERY slowly.

OK, Sweden is one thing - no Teslas here, but Norway, with 2'000+ Tesla S:s sold and counting???
Doesn't anyone check these things first? If Tesla's UMC doesn't fit into the built-up network of public chargers,
why on earth don't they either redesign the UMC or produce a safe accessory short extension included with the car??
To me it is obvious that the outlets have to built into some kind of cabinet, to withstand rain, hail and snow. These cabinets are too small for the Tesla UMC plus added last part. Not everyone can always drive to a Tesla Charging Station - it might be on the other side of the town - or indeed not at all, and they may be a long ways from home. So why don't they prepare the cars so that they fit the local systems??? Doesn't sound very smart to me. Actually, it is downright stupid. And frustrating: "here is a charging station, but we made sure you cannot charge with the original parts, and you're not allowed to buy any other. Walk home".


To Gt1Cooper: yes, that's an obvious MO, but the thing is that if something/anything happened to the car while in the airport, say, charging through an extension, the warranty would be gone.

Extension cords are fine as long as you get one with the right specifications. Know how much amperage you are going to draw, know the wire gauge of the cord, and make sure the gauge can handle the amps.

Note that the original poster is European, and thus the plugs, receptacles will be different than any US extension cord.

Obviously you need a cord rated for the charge current. 14 gauge (rated for 15 A) is what I use for 120 Volt since the car will only draw 13 A.

If you you using a really long cord you may want to look at 12 gauge to mitigate voltage drop and slower charging.

I bought this one for a new NEMA 14-50 installation at a vacation home. Works perfectly.

@rbarry: That's pretty much it, right there. RV owners regularly use long 30' and 50' 14-50 extension cords drawing heavy current. It's just that they know they have to buy expensive, heavy-gauge cable. For example, the one you linked to is 6 gauge, which should be plenty capable of handling a sustained 40A from 14-50.

I can see Tesla's position from a legal standpoint, but from a practical standpoint if you're smart about it you shouldn't run into any issues.

Yeh. As long as you use appropriately gauged wire for the length you're using, there shouldn't really be a problem. As already noted, it probably shouldn't be coiled either.

I think the reason they say no extension cords is that most of the ones out there can't handle a constant 12A of current. In my case I bought this which works beautifully.

Anything 12 gauge or lower should be fine, though I would limit the length of 12 gauge to no more than 50 feet.

I also made a 20 foot 10 gauge extension cord to go from the dryer outlet in my garage so I could plug in the UMC which worked beautifully. A few weeks ago I installed a HPWC so I no longer have that issue.

I also picked up a 50A extension cord which came in handy when I drove up to my parents' time share in Lake Tahoe since the UMC would not reach the outlet without backing in. Since the space was so narrow I was reluctant to back in but this also worked quite well:

I ordered a 20 ft. Extension with a 3 prong converter from a 220 to my Tesla cord. Works great and they got it to me in one day for a cost of $70. Look them up at They know what they're doing and have done a lot for Tesla owners.

Macdaddydude, you nailed it.

The entire electrical distribution system is basically an extension cord. It works because the wires are sized for the loads. Use the correct wire sizes and extension cords are a total non issue.

Macdaddydude was right. They, Tesla, assume the average consumer will go to Walmart and buy a 16 gauge 100 foot cord on sale and wonder why it burned up.

Again, thanks for your comments.
They don't really answer the warranty issue.

As far as I see it, we have the following situation:

- the UMC has a "fitness" problem. It doesn't fit in the official electrical charging outlets in Norway or Sweden (and presumably elsewhere).
- That means that we cannot charge the car in places, foreseen to charge cars (except Tesla Charge Points, of which we have precisely 0 in Sweden).
- The Manual expressly forbids the usage of an extension cord. We would only need one a foot long to get out of the charging outlet cupboard!!! If we use one anyway and anything happens, related or not, good-bye warranty.
- Tesla do not provide an approved one. Nor do they recommend any certain brand with certain specs that one would be allowed to use.
- The only thing they'd have to do is to produce an adaptor to the UMC that, rather than snapping on to the UMC (making it even bigger), has a short cable between the UMC and the other contact, to enable the UMC to be hanging free, outside the cupboard.

Anyone but me to think that the Tesla just reduced itself to being a commuter car? Would that they had thought things THROUGH before pushing it to the market. I mean, charging the car is a rather essential part of driving a Tesla...


Robert - how many different outlets are in the US... too many that even a seasoned electrian doesn't know them all. How many outlets are in the world? If Tesla would deploy a team to figure out all the different outlets in the world we would run out of oil before they are done.
We had the same problem here in the US at the beginning... shop made a nice pdf which helped me out many times Maybe a similar document is available or should be created for Europe.

No, Kleist, you're missing my point completely.

Tesla ARE already making the different adaptors (how could they otherwise sell the car?, and in continental Europe there is only one sort anyway, just the English have a different one). My only gripe is that, when the adaptor is clicked on to the UMC, the whole thing is so outsized that it doesn't fit into a charging cabinet. If they had added a foot of cable in the adaptor, everything would be spiffing.

But they don't. And forbid us to do it.


@rbarry wrote:

"I bought this one for a new NEMA 14-50 installation at a vacation home. Works perfectly."

Anyone notice the customer photo on that product?

Kleist and TomN

Yes, but none of these have the European contact. The European is 2 round pins into 2 holes (and Earth somehow)


Robert - I got your point. How many different boxes you can buy for 14-50 in the US? Leave it to the electrician and some will not fit the UMC. I just had my experience with my seasoned electrician installing a 14-40... His suggestion silly box, undersized wiring - thanks to the forums I could tell him what I needed. The world is not ready for EVs yet.

Robert - My comment was just to call out the fact that the customer photo was a shot of @EFusco's Model S, not to make claims about the product itself.

Sounds like a business opportunity. Make a 2 foot pigtail for the Swedish market. Sell them online. Problem solved. I would do it for you but by the time I traveled to Sweden and back to do the design there would not be enough sales to cover the travel costs.

The extension cord thing is just because there are lots of people that don't know an amp from a chicken sandwich. Don't lose to much sleep over it. The wires to your charge cabinet are basically extension cords also.

I don't know about Sweden but in the US I could go to a hardware store and make a custom pigtail in about an hour.


I think what you might be looking for is a short Schuko CEE7/7 cable perhaps. That's two round pins with a ground for about 15 amps at 240 volts or so.

So it sounds like you have a clearance problem getting the plug end of your mobile connector into the outlet because while the plug is correct, the adapter is too large to fit the space.

Yes, you can have a short cable made up for you. You need the male and female ends a foot or two of cable. As an electrician friend to make it for you. Use very heavy duty wire with extra capacity. Your electrician will know.

So long as the wires are connected correctly, you will not damage your car.

The reason they say not to use extension cords is people would use light duty cords like you would find at a home store for use with a small lamp.

A short extension cord of correct gague and insulation with the correct thermal rating is functionaly equivalent to hardwire in your wall.

Yes, I know exactly what I need, and I do have an electrician that could do it for me. And I will ruddy well have to, if I want to charge the car. He wired my whole house and the solar cells. I believe he can make this "pigtail" in his sleep.

The point is still the same: Tesla ought to have done it themselves. Or at least not forbid a professional to do it, while supplying the minimum requirements for how to do it (cable thickness etc).
This way, the way I read it, even if I let a pro do it, the Warranty is gone, should anything happen. I am not about to take on a Tesla Company law firm, saying: "Explicit instructions not obeyed. Go home."

Even if the fault could be entirely Tesla's, and the Battery exploding or burning or shorting or whatever, they would get out of it, if I used a however professionally made pigtail.
THAT's my point.

And a second one is that we're adding the number of adaptors, which is never a good idea. Instead of one adaptor (the one made by Tesla), we're now having 2.


Robert, your point, clearly made is the fact ANY adaptor cable is specifically not approved and potentially will void your warranty. SO, I suggest the following:- write to, explain the problem, preferably with a photo, provide your solution ( a short pigtail extension professionally made) and ask for written instructions. That way you will be covered and your problem solved by the work around. Jerome is an engineer and and VP of sales and marketing. His authority is senior enough to speak for the company.

X Deutschland Site Besuchen