10-30 to 14-30 adapter and charging advise

[sumitkgarg]

I guess I found my answer below regarding the extension cords. Although it is not as per the code, I will be creating an extension cord using an AWG 10 wire that is about 15 feet in length. The extension connector will be properly sealed and put somewhere safe to minimize any risks that may arise from water on the floor, etc.

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CAN I USE AN EXTENSION CORD?

Tesla Motors makes it clear that an extension cord is not to be used with its UMC. The NEC requires that you follow manufacturer’s instructions, so technically you violate the NEC by using one.

The NEC contains some rules for using extension cords. Some of the rules state that extension cords are not permitted to be used as a substitute for the fixed wiring of a structure; run through holes in walls, structural ceilings, suspended ceilings, dropped ceilings, or floors; run through doorways, windows, or similar openings; or be concealed behind building walls, structural ceilings, suspended ceilings, dropped ceilings, or floors.

However, as to the question of whether it is safe or not… Technically, yes. With the right size conductors, an extension cord, whether 120V or 240V, is relatively safe in limited lengths.

For 120V, to keep the voltage drop within range, you can use a 14 AWG cord if your TOTAL one-way circuit length from the car to the breaker panel is < 50 ft., 12 AWG if your total is < 100 ft., and you'd need to go to 10 AWG if you're at 150 ft. or greater.

For 40A charging @ 240V (NEMA 6-50, 10-50, or 14-50), you should use 6 AWG, and your total one-way circuit length can be 300 ft, with voltage drop at reasonable levels.

For 24A charging @ 240V (NEMA 6-30, 10-30, or 14-30), AWG 10 is good to 200 ft. one-way from breaker panel to the car, go one gauge up (AWG 8) if you need more.

As mentioned, keep your cord to the smallest length possible to reduce voltage drop and increase your charging efficiency.

Keep in mind the potential insurance implications of this, as mentioned above. You are violating the NEC in the US by doing this.

 

[sumitkgarg]

Just in case if anyone is looking for an official Tesla 10-30 adapter (not 14-30), they are available at tesla.com now...

Model S/X NEMA Adapter

 

[MP3Mike]

At a high level, my plan is to use the 10-30r (or 14-30r) receptacle in the wall with Tesla's official 14-30p adapter on the other end. I think that takes care of the accidental current overdraw and because of that, I don't think that I need to do anything special with my Zinsco breakers. The risk with the Zinsco breakers, as I understand, for me remains the same as before.

Nope you will be greatly increasing your risk. You may be drawing more power over a longer period of time.

Those panels/breakers are so bad that some insurance companies won't insure houses with them.

 

[sumitkgarg]

Are they just "that" bad? They will burn the house if I am charging my car at 24A on a 30A rated Zinsco breaker? Why aren't they outlawed and why are they still available for sale online?

Ranting aside - is there another brand of breakers that will fit just like them without me having to replace my entire panel?

 

[gregd]

Are they just "that" bad? They will burn the house if I am charging my car at 24A on a 30A rated Zinsco breaker? Why aren't they outlawed and why are they still available for sale online?

Ranting aside - is there another brand of breakers that will fit just like them without me having to replace my entire panel?

I had (past tense) a Zinsco panel in our early-1980's home. Our electrician, hired to look at installing a 14-50 in the garage, was surprised to see it; he thought that they'd all been replaced by now. Based on this, I don't believe they are still for sale, especially for new construction. There may be replacement parts still on the market, but that's about it. The electrician also noted the issue with some insurance companies refusing to underwrite a homeowner policy when these panels are in use. Ours didn't ask, so I didn't know about the hazard, but I didn't check around regarding this issue either.

All that said, when we replaced the panel last December I asked the electrician if there was any evidence of a failing contact, and he said there was none. So, some may last for some time, depending on what conditions I do not know. But given that our home could have burned down several times over electrical issues (*) not related to the panel, I sure sleep better at night knowing the old panel is gone. If you have the means, your priority should be on swapping out that panel, before considering what sort of charging you can rig up. With the panel swap, other charging opportunities will likely be available. I now have a nice stiff 14-50 outlet in the garage, and a couple of 20-amp 120 volt outlets too, which were practically free "while we were in there".

The issue with the Zinsco system is not just the breakers, but how the breakers and panel connect mechanically. So it's a whole system swap, not just a parts replacement.


(*) All of the connections between wires in our house were done with crimp rings. This is apparently ok for grounds, but the builder's electrician (not our current one!) used them for the hot leads too. Twist the wires and "secure" with a crimp ring, insulate with electrical tape. How it was signed off is beyond me. Over time, they started corroding, building up heat, which caused the corrosion to accelerate. Bad cycle. First instance was detected by my wife who wondered why a wall switch plate felt warm. Another joint happened to fail in the box directly behind the (only) smoke alarm in the house, setting it off. After that, I went around the house and opened every outlet and every wall switch and redid every connection with wire nuts. Except I missed one, hidden behind some furniture. A few years later, that one failed while we happened to be watching TV in the room, and smelled the smoke. So I urge you, please take electrical issues seriously.