240V 100FT Extension Cord

240V 100FT Extension Cord


I installed a 240V outlet in the back of my house and want to run a 100FT 240V extension cord to recharge my Model S. Has anyone done this, and if so, what mfg extension cord mfg would you recommend?

Thanks for you help.


DTsea | 13. November 2018

Tesla says, do not do that.

TMS | 13. November 2018

Numerous people charge with extension cords just fine, now whether they are 100 feet and 240V is another matter. You might want to consider dialing it back. I personally feel comfortable with 16-20A being pulled with a 10 guage over that distance for regular duty but this assumes there is no other reasonable option.

barrykmd | 13. November 2018

Using an under-rated (<50A rating) extension cord and dialing the current down is a bad idea, Besides violating code, if someone forgets to dial it back before plugging in - poof/sparks/fire/etc. You don't want the extension cord to be your circuit breaker!

There are some RV extension cords on Amazon, but I didn't see any longer than 50 ft. Could you use 2 of them? Sure, but probably not a great idea. You want 6 ga wire and it's going to be heavy.

tes-s | 13. November 2018

My suggestion is put the outlet in the right place for charging. If you make your own extension cord, make it the right length with 6/3 SOOW cable and 6-50 connectors. 25% less weight than a 14-50 with 4 conductors. Also less cost.

DanFoster1 | 13. November 2018

Curious why you don’t run an appropriate cable from your panel to your parking area? I ran nearly 100 feet of 6 gauge for $317.38 (not including the Tesla Wall Connector I installed which you don’t need.) Two, high-quality 50 foot NEMA 14-50 extension cords would cost at least as much, and add points of failure.

You’d need a couple really heavy cords, my dude. Keep the amperage at 80% of rated capacity or below and it’ll be fine—high tension wires are just very long cords too ;~)

If you’re gonna do this long term, keep a good eye on all the points of connection: be sure the contacts are clean, and making solid connections. If they get crappy they’ll overheat, or perhaps the car will notice the voltage drop and dial the current down—Teslas are super-good about that. But…yeah, keep everything clean and firm.

RandallKeith | 13. November 2018

+1 Dan
100 foot extension cord will cost more then a hardwire.

murphyS90D | 13. November 2018

A 50 amp extension cord would have to be at least #6 wire. At 100 feet it borders on needing to be #4 wire. That is going to be a very heavy cable.

kerryglittle | 21. November 2018

Why would anyone cheap out on a proper charging outlet after spending big bucks on a car? Not to mention burning down their house. :-/

bmiksa | 11. Januar 2019

Fred is probably considering the 100' extension cord for the same reason I am--- Because of the relative location of my circuit box and garage, electricians want over $2,100 to install the charging outlet in my garage!

barrykmd | 11. Januar 2019

My run was 300 ft and it cost be about $1300. That was 3 1/2 years ago. has the price of copper gone up?

Bill_75D | 12. Januar 2019

2 years ago I paid a licensed electrician $750 for a 125' run of #6 copper wire, a 50 amp circuit breaker, conduit, and an industrial grade 14-50 outlet.

deemo | 12. Januar 2019

I use a 30ft RV extension cord rated at 50 amps to charge a Model S (and 3) at 40amps, no issues. Cost was about $100 on ebay. Allows total reach of a little over 50ft with charger cable length.

p.c.mcavoy | 13. Januar 2019

Cost of the run is not just about the distance of wire. Mine was about a 75’ fun to put a 100 amp sub panel in my garage as the main panel was on the opposite side of the house. Issue is the panel was in the basement, finished ceiling, plug the floor joints running perpendicular to the direction of the run. Much of my cost was due to the roughly 35 feet of finished ceiling that had to be opened up to allow joists to be drilled to get across the basement.

Point is, without knowing all the details of the installation, comparing installation costs is about as useful as comparing insurance costs with no consideration of location, driving history, age, and the other factors that can impact cost.

L.ray | 02. Mai 2019

I just purchased a new model 3— I’m building a house which should be done in July. I drive 200-300 miles a day for work. I need a quick fix that will allow me to charge on my dryer plug in. I know it sounds cheap however my temporary housing (town house) will not allow me to install a 220 plug. I would like to get around 100 feet cord to connect it to my dryer plug.

Thoughts professionals?

Putt Putt | 02. Mai 2019

A 75 ft marine cable/ 50 amp is $741.00 on Amazon. Those cables are almost the size of the wall charger cables....75 ft is the largest listed.

tes-s | 02. Mai 2019

30amp dryer outlet? I would get the appropriate length of 8/3 SOOW cable and make my own with a 14-30 plug on one end, and 6-30 receptacle on the other. "Could" get away with 10/3 and save about $50, but I'd go a little bigger because of the length.

Figure about $300. If you go with the smaller cable (lighter too), just dial back the charging to 20amps instead of 24.

tes-s | 02. Mai 2019

BTW, I'm not a professional and Tesla says not to use extension cords.

murphyS90D | 03. Mai 2019

There is nothing wrong with the proper extension cord.

The problem is that the extension cord that people usually have laying around is built with 16 gauge wire or even 18 gauge wire. Those are way too small to use with the car.

I have a 50 foot 10 gauge cord that I used at my brother's house before Charlottesville, VA got a supercharger.

radio | 05. Mai 2019

I have installed about 32 meters (100 ft) of 6 mm2 wire (AWG 10) between my panel and the socket in my garage (CEE blue 32A within the same building). These 6 mm2 work perfectly fine for charging with my UMC at the possible max. rate of 7,4 kW (= 230 V x 32A, single phase) and the wire hardly gets luke warm so it's a perfect fit. I could have used a 3x4 mm2 wire (AWG 12) as well but would have had some heat losses when charging at full rate.

I did the wiring myself, but that was easy within the house. Running a wire outside across the floor/ walkway/ garden gets you into some possible issues concerning people tripping or lawn mowers running over it so it would be necessary to bury the cable, if possible You need a "protected" cable for that, which is about 100 € here in central Europe and has an additional rubber layer. Also it would be important to install the socket to the wall as leaving it on the floor is prone for disaster if the cable gets flooded, pulled upon or run over by a car. In any case it is advisable to have an electrician check out your connection.

ChrisH314 | 06. Mai 2019

You don't say how many amps.

radio | 06. Mai 2019

32 amps (=7,4 kW, single phase) is the maximum current that the Tesla UMC pulls here in Europe when using the blue CEE 32A connector. With the red CEE 16A 3-phase connector the UMC is limited to a max. of 3 x 16 amps giving 11,5 kW in total, but I guess 3-phase combinations are uncommon in the US.

@OP: To my understanding the Tesla UMC in the US maxes out at pulling 10kW in any case, so an AWG 10 cable is fine for a length of 100 feet if you use a 240V installation as stated. If you plan to upgrade later to a Tesla wall charger which maxes out at pulling 22 kW the AWG 10 cable would only be sufficient if it's a 3-phase installation (= 5 wires/leads), but I am not sure wether you commonly use such 5-wire installations over there (3P+N+Ground).

Bighorn | 06. Mai 2019

Earlier Model Ses with dual chargers drew 19.2 kW here. So newer models are half that, but the gauge of the UMC wire is narrower now.

radio | 06. Mai 2019

Are you sure drawing 19.2 kW is possible with the portable UMC plugged into an extension cable or simple dryer socket? In Europe we always max out drawing 11,5 kW with the UMC in any configuration/connection.
Only with a Tesla Wall Charger (or other specific wall chargers and cables) we can use the full capability of the onboard charger and draw 16,5 kW or even 22 kW with the older dual onboard charger. The reason for this UMC-limitation is that it would need a special "FI 3-phase security switch" (residual-current circuit breaker) which it doesn't have and hence is limited to 11,5 kW (=3x16A@230V or 1x32A@230V).

Bighorn | 06. Mai 2019

Good point. It’s the wall charger that provides up to 19.2 kW. The UMC is limited to 9.6 kW by virtue of the adapter options. I think the gauge is similar, but am not sure.

murphyS90D | 06. Mai 2019

The UMC requires 6 gauge wire.
The wall connector requires 3 gauge wire if 80 amps will be used. 3 gauge, like all odd gauge numbers, can be hard to find so I used 2 gauge. That was better anyway because it was a 75 foot run.

radman4 | 23. September 2019

we recently bought a model 3. then I ordered a model S. we had a licenced electrician install a 240 V 50 amp outlet on one side of the garage. now that I"m getting the second one, not sure how to charge. its a four car garage and the model S will be parked about 15-20 feet away from the outlet. is it ok to just run an appropriate extension cord? can I hook it up to a splitter at the outlet so potentially both can be charged at the same time? (don't want another outlet since the house will be sold in several months)
thanks for your advice.

murphyS90D | 23. September 2019

You will have a tough time finding a 240 volt extension cord built with 6 gauge wire. The maximum charge on a 50 amp circuit is 40 amps. With two cars on the circuit they both would have to be dialed down to 20 amps. Do you exhaust your battery every day? I charge my car once a week. Charge them on alternate days.

Bighorn | 23. September 2019

.I just jockey the cars to the faster charger as needed and 120V trickle the second. I have two cables though.

Roger1 | 23. September 2019

@ radman4, since you are selling the house in a few months why not alternate between parking the M3 and the S by the outlet in the garage? Nothing to buy and no electrical problems to solve.

When you get to your new location, put in a pair of Tesla chargers to share a single supply line and breaker. You have to install a wire (audio cable) between the units that lets one HPWC act as the master while the second unit is a slave. The master unit defaults to allocating power equally between the two HPWCs then monitors power used by each car. If one car does not fully draw its half of the power then the master HPWC changes the allocation to give more to the car that can use it. If a car is connected but not actually charging then all the power is available to the car that is charging. I have a pair of chargers set up this way - one for my car and the second for visiting family members' Teslas. The arrangement works well as I typically schedule my car to charge late at night so the visiting car gets full power.