Charging in a non-secure location

Charging in a non-secure location

Yikes! Someone posted today that a replacement charging cable for a Model S costs $1800. Since my Model S will be charged in a non-secure location (I live in a condo), I'm very concerned about a black-market in stolen charge cables, and mine disappearing one night. Anyone that lives in a condo or apartment, has a carport, or charges at a public charging station could have their charging cable stolen in an instant.

TM - could you please consider imbedding the necessary chip into the cable plug so that it could be paired to the vehicle, just like the fobs are? Without a secondary resale market there will be little incentive for someone to steal one.

Also - has any current Model S owner asked if their auto policy covers the theft of a stolen charging cable? I know some policies exclude thefts of items in unlocked cars, and I assume a charge cable falls into that "unsecured" category.


TikiMan | November 5, 2012

I think it 'locks' into the port when it's charging, and can't be removed unless the fob is present.

Val | November 5, 2012

That's correct. See p18 of the owner's manual.

Getting Amped Again | November 5, 2012

Thanks TikiMan and Val. Wish there was an Remove Post function.

Getting Amped Again | November 5, 2012

"a Remove Post function". Now I need an Edit Post function.

Volker.Berlin | November 6, 2012

It's actually a very interesting topic that has spawned one of my favorite threads on these forums:

Brian H | November 6, 2012

Sign in the window: Danger! High Voltage!

William13 | November 6, 2012

1 the cable locks in place.
2 I bought a cheap and easy heavy plastic locking gizmo that works by driving a tire onto it with channels underneath to hold/ secure any cable. It is made a fellow Tesla owner. Search for it in the
3 the cable price that you reported is too high. Recheck your price. However it is currently made out of unobtainium. They would likely rush one to you if you claim theft but currently you can't get a second one.

prash.saka | November 15, 2012

What about the case where you have to lock the power outlet?

We live in an apartment complex and will have the electricity consumed from the outlet be charged (pun intended) to us by including it along with our electricity bill.

In this case, is there a way to block access to this outlet? We just want to prevent others from freeloading (similar to Wi-Fi signals) at our expense.

~ Prash.

Getting Amped Again | November 15, 2012

@prash.saka - I have the same problem as I live in a condo. I couldn't think of anything but a sign (laminated sheet of paper) saying "Electricity from this outlet is being paid by apartment ___. Please do not use."

Are you running a 240V line? If so it's unlikely anyone would use it unless they had an EV also.

jbunn | November 15, 2012

Prash, Getting Amped,

The 240 volt and 120 volt outlets have a cover plate that can be removed and replaced with what is called a "foul weather" cover. Here is an example of one for 120 VAC

Cost is under 9 dollars. You should be able to fit it or adapt it to allow for a small padlock. These types of covers close over your plug end, so when locked will prevent the plug being removed from the wall. They are also suitable for outdoor use, for homeowners that are considering putting an outlet out on the drive.

Questions? Let me know.

Getting Amped Again | November 15, 2012 - that's a great solution, thanks. The description says "lockable tab" so I bet it's ready for a small padlock.

Thanks again. That's way better than my sign idea!

jbunn | November 15, 2012

You are welcome. If you do decide to get a "Tesla Only" parking sign, you might want to check Cafe Press. Basicaly, just upload your design, and it shows you what your design looks like on a variety of products, shirts, mugs, postcards, signs, ect. You can order a quantity as small as 1, deliver is quick and the price is quite reasonalble.

prash.saka | November 15, 2012, thanks a lot buddy.

@Getting Amped, the installation is not yet done but it will most likely be a 240V line. And I was worried about having other electric cars charge using our outlet.

~ Prash.

jbunn | November 15, 2012


You're welcome. Since you haven't had it installed, pick up a cover and give it to the electrican. Won't be a cost, since he's got to put a trim plate on it anyway. You're in Silicon Valley, I believe? Should be easy to get.

dahtye | November 16, 2012

One comment...

The 240V charging plug on the Model S charging cable is quite large. The photo shows the cover will only prevent unauthorized use but will not protect the cable from being extracted from the outlet. I don't know if anything exists that will cover the large 240V plug securely.

Volker.Berlin | November 16, 2012

dahtye, once the smartphone app is there, it will ring an alarm when the car is unexpectedly disconnected from the grid, and/or the car may be able to send an SMS, even to your "dumbphone" (I doubt that there are any Model S reservation holders that do not use a smartphone, but you never know). Some such solution will become available soon.

I understand that it's probably preferable to stop the cable from being disconnected in the first place, but if you cannot have that, then maybe the being informed in a timely manner is a welcome second-best solution.

dahtye | November 16, 2012

Yes, but it would also not prevent someone from taking the 240V conversion adapter. This adapter can be attached to the outlet side of the cable and it locked only by a mechanical button (no electric interlock that I can see).
Not sure what anyone would want with it, but there are strange people about who might think it cool to have (sort of like those people stealing Mercedes hood ornaments).

prash.saka | November 16, 2012

@jbunn ... au contraire, I live in Boston. About getting it installed by the electrician, I think it is a good idea and I'll take your advice.

~ Prash.

jbunn | November 16, 2012


Couple ways around this. Since the cover locks, it would be difficult, but it's open at the bottom. Reduce the size of the opening with plastic attached on the inside of the cover. Or put a cable loop around the plug end, and attach to the padlock tab. To fasten two cables securley together, take two short lengths of steel cable and permanently affix a short piece with a duplex nicropress to the mateing ends of each power cable. Steel cable loop must be small enough to not be able to pass over the electrical plug. Next make a small loop in each steel cable and secure with nicropress clamps. Once the power cables are together, padlock the two free loops together. You can make one up for the other end of the non-Tesla power cable as well. Make it a bit longer, and you can padlock to conduits, posts, or other nearby objects. You can see what a cable clamped with nicopress looks like here;

Remember though, a determined thief will pretty much get though anything you come up with. Padlock something, and he'll bring a bolt cutters. The thing is though that thieves are not by nature ambitious. If they were, they would have bigger targets in mind than your cable. So if it looks like more trouble than it's worth, chances are they will leave it alone. You're just trying to eliminate "crimes of opportunity", and they will move on for easier prey.

dahtye | November 16, 2012

Ah yes, that appears would work.

Now, another one that I just realized by reading your post....

I purchased a heavy duty 15 ft extension cord that has NEMA 14-50 at both ends. [I know we aren't supposed to use exension cords, but it does apparently work without voltage loss since the cords wires are very low AWG]. Thinking that someone might want to steal the extension cord, it makes sense that I could use a padlock to lock the Model S charger cord and the extension cord together near where they mate. This would prevent a quick theft of a cord that costs about $70. And I can detach them easily by releasing the lock when I don't need the extension.

BTW, does anyone know why Tesla advises against using an extension cord? IMO, if the wire gauge is big enough, there should be no difference between plugging directly or using the extension cord. The voltage drop in an in home install could be higher than the extension cord - depending on how long the run is from the main panel.

jbunn | November 17, 2012


Stranded has the same cross sectional area as solid wire. (One foot of copper stranded uninsulated would also be equal weight as the same lenth of solid copper.) Because stranded wires is not as DENSE however (air between the strands) the wire APPEARS larger. This means that the normal 120VAC drop cord like you might buy at Home depot is a not as robust as the same lenght of 12 gague romex. Voltage drop becomes very noticible.

Voltage drop between the same gague wire for solid and stranded is the same but an extension cord has a much lower ampacity and higher voltage drop that one would exepct based on it's SIZE, leading people to underestimate the cord. Their statement, i think is to discourage casual use of cheap dime store extension cords. If on the other hand you have an 8 gage stranded 4 conductor cord with Nema 14-50 plugs of a reasonable lenght your voltage drop is 1 or 2%. Not bad. We use this type of cord all the time in boating, and I imagine RV folks do as well.

Hope this helps.

Brian H | November 17, 2012

Remember that current flows only on the surface of each strand, so the multiplied strands makes them much more efficient than solid.

nickjhowe | November 18, 2012

@Brian H - I thought that was only true at very high frequencies - that is why microwave towers use 'waveguide' (hollow, square cross section tubing) instead of cable. At 50hz I thought most of the cross section of the cable supported electron flow.

nickjhowe | November 18, 2012

Forgot to add - I though the reason for smaller strands was to allow flexibility (at the cost of thicker overall cable diameter as described above)

Brian H | November 18, 2012

Electrons repel each other as far from each other as possible. Also why a Faraday cage works. (Ever seen the demos of guys standing right beside Tesla coils, being hit by megazaps? From within flimsy Faraday cages, and nothing touches them.)

jbunn | November 18, 2012

In direct current, the charge is evenly distributed through the cross section of the conductor. At high frequencies the "skin effect" becomes noticible where electrons prefer to flow on the outside of the conductor. Microwave frequencies do use wave guides for that reason. But 60 cycles is pretty slow. Residental electricians dont consider the skin effect when determining ampacity because the skin depth is about 8.5 mm, but they do use stranded wire in the larger sizes (smaller gague numbers) for flexibility. Wiring a 200 amp service would be almost impossible with solid wire.

Brian H | November 19, 2012

Yes; the magnetic effects of field collapse in AC dominate at high frequencies. I didn't understand or consider that.

Tiebreaker | November 19, 2012

Stranded wire lowers losses due to eddy currents.

Extension cord use is also discouraged because of the added contact points, which can corrode, collect dirt, become resistors etc. And how many extension cords can you safely string? 1? 2? 14?

jbunn | November 19, 2012

When I put my compressor on 75 feet of 14 gague extension cord, it wont even start, the voltage drop is that bad. I do have a very heavy 10/3 cord of 50 feet, which you can get at home improvement stores. As tiebreaker says, the ends are the weak links. I would use this cord for occasional 120 vac use without reservation though, as its pretty heavy.

riceuguy | December 10, 2012

As I get ready to bring out the electrician for an estimate, can anyone let me know how long the included charging cable is so that I can start thinking about where the outlet needs to be if I don't want to have to back into the garage? Or, is there an extension cord that anyone here is using on a regular basis for 14-50 that's working reliably?


jat | December 10, 2012

Extension cords aren't typically rated for continuous use (>3hr). I would imagine if you had a properly sized one, including 25% derating for continuous use, you would be fine. For 110V, if you could get a 20A extension cable you would probably be fine. For 240V, you would probably have to make your own.

ReeceWeb | December 10, 2012

A heavy-gauge well constructed extension cord is electrically indistinguishable from in-wall wiring.

A light-gauge or poorly constructed cord will have a higher voltage drop at any given charging current. That voltage drop is converted into heat (voltage drop * charging current = watts of heat) which can be very dangerous if it causes the extension cord to fail. Also, poor quality extension cords may become damaged from foot traffic, weather, etc. compromising the insulation.

Does anybody know what the brick in the mobile power adapter does (other than have green LEDs)? My assumption is that it is a safety device that disconnects the power if the car isn't attached, and it may also contain over-current and ground-fault protection.

If so, then Tesla might also advise against extension cords because the extension attaches upstream of the brick. This would increase the chance of a passer-by coming in contact with a high-power line without these safety features.

mrspaghetti | December 10, 2012


The connector is 20' long.

Beaker | December 10, 2012

The mobile cable (and HPWC & Supercharger) does lock into the charge port when the car is locked, and thus will not be removable.

However the adapter at the the other end is not locked in place and could be unplugged from the wall and from the mobile cable, even during charging. So you only need to be worried in a black market for adapters. :O

tezco | December 11, 2012

I charge with a J1772 and the adapter. I've noticed that when I disconnect the J1772, the locking mechanism holding the adapter in the charge port unlocks. Unless I pull out the adapter within a few seconds, the lock engages again and the adapter is stuck. Unlocking the doors doesn't release; I have to access the touchscreen to "open the charging port", which once again unlocks the adapter.

The most worrisome thing is that simply disconnecting the J1772 causes the car to unlock the charging port (and adapter), even when you walk up to a locked car without the key fob. Be careful at public charging stations--I'm sure the J1772 adapter isn't cheap.