Can I just ask, are you getting permits for this? If it were a single family house you were talking about, nobody would ever know. But we’re talking about a condo building where some residents, present or future, can be nosy or demand that the condo board install a charger for them like they did for you, and then things spiral out of control…
not only that, but at least where I am the management company owns the structure and everything inside the walls (electrical, plumbing, etc.) They would take a dim view of me doing un-permitted and un-inspected electrical work.
Just to note, the standard $9 14-50 outlet that home depot/lowes offers doesn’t support a whole lot of plug-unplug cycles. Probably fine if you just leave the cord plugged in to the outlet all the time, but not ok if you plan on taking the charging cord with you. Tesla recommends a more robust 14-50 outlet that costs significantly (80 vs 9) more.
This is pretty Neanderthal-level circuit design. The relay IS the isolation, and the 24v relay drive IS the low voltage. (But I acknowledge that it must feel weird if a lot of your prior design work is semiconductor low-voltage stuff; you isolate the external inputs like hell in that setting, using optoelectronics like you describe.)
Why would anyone carry their 240V charging cord with them? It might make sense to carry a 120V charger around (mine is in my Volt, though I can’t remember the last time I used it). But where would you find a 14-50 plug by a parking space?
At your friendly neighborhood welding shop, obviously… 
That’s the plan. The permitting and inspection process looks pretty straightforward. I need to continue reading the code for little details like the exact spacing of the cable brackets, etc., but I don’t think it’ll be hard to get that right.
There is an architectural review process that I plan on using. Oddly, it doesn’t mention electrical work but in any case this is the right process. And being in CA, they can’t deny a reasonable request, and since this doesn’t involve any changes to common areas, I think it’s pretty reasonable. As an aside, I actually won’t be doing any work inside the walls. The fusebox I’m using as the source and everything else will is on the near side of the drywall.
I think a reasonable request includes utilizing the services of a licensed electrician. YMMV.
You’re right, it depends on what the availability is for 14-50 at wherever you end up going. I believe RV parks tend to have 14-50 available.
Also note that Tesla’s corded mobile connector defaults to drawing 32A on a 14-50, which isn’t going to work with Dr S’s 30A fuse, nor will anything else designed to run when on a 14-50. May want to consider a NEMA 14-30 plug instead.
You can set the car to draw fewer amps and it will remember it based on GPS location.
Upon reflection, a 14-50 is probably against code, due to the presence of the neutral pin–which I do not have (only a ground) and would have to leave disconnected. I’d have to use a 6-50 or perhaps a 10-30 instead.
The 10-30 is a bit confusing as the third pin is designated neutral, not ground, although apparently old code revisions allowed using neutral as ground. Weird, and probably to be avoided if I want to pass an inspection. The 6-50 plug explicitly declares the third pin to be ground and is probably the better way to go. Tesla has adapters for both of those.
You win the donut. The HOA manager says it’s actually part of “building code” to only use licensed electricians. That sounds a little dubious but in the interest of keeping everyone happy I guess I’ll stick with the electrician. They don’t in fact need approval since it’s not in a common area.
That said, I think it’s still possible to build the relay box and have the electricians install it and the rest of the stuff. Won’t be as cheap but whatever. It’s not far off from what they suggested anyway; it’s just that it’ll be automatic as opposed to a manual switch.
It’s also in the law I cited earlier. In my experience HOAs will require licensed contractors to do all work that touches common areas. For things inside the residence, I believe there is a dollar threshold and type of activity threshold that would require permitting as well which means licensed contractors, but that is less stringently enforced.
Right. The “philosophy” of safe electrical work is actually pretty logical and easy to understand, but it’s a few steps below what I’d consider best practices for, say, PCB design. From my viewpoint, I’m only an insulation-width away from a 240v shock, but in reality there are a number of passive aspects to the design that make that highly unlikely.
Yes–they cited the same law to me. There is clearly a big difference between common areas and personal, however, and this work will be entirely within my individual garage.
This is the first I’ve heard of a dollar threshold, though. Any cite on that?
I visit my parents a fair amount and they have a 14-50 for a welder handy. Also, the “mobile charger” for the Tesla is the same for all plug types; it just has a few swappable pigtails on it. I’d take the whole thing if I expect to do any non-public charging on a trip.
Actually, I think I’m wrong on that. For some reason in my head I had it that over a certain dollar threshold there was a permit required, but I can’t find that as related to electrical work. I think for general construction it may be the case. Here’s something from Seattle:
But I think you are closer to Fremont if I recall correctly. Fremont has specific permits for electric vehicle charging stations. But generally for electrical work, the City of Fremont will require a permitfor most things above very minor items.
Though relating to electrical work, Fremont also identifies these things that do not require a permit (pdf):
What I don’t know is if a permit can be pulled from the owner if unlicensed. Perhaps you can get the permit without the aid of an electrician, but I can’t seem to find that.
The idea is you have your home charging station where the wire doesn’t leave. You keep the cord that came with the vehicle in the vehicle in case you are out and about and need to charge.
I looked around and there is apparently a $500 threshold for contracted services–work under that amount can be done by unlicensed workers. The law only applies to advertised services, though, not people doing their own work.
I believe that I can get a permit without being a licensed electrician. In fact, I think I can get a permit online. I’m in San Jose and they have this website. They have a table for what permits can be applied for online: although the “Electric Vehicle Charging Station” category is not checked for “Multifamily properties”, it is checked for “Receptacles / Switches - New”. And really this is just a new receptacle installation, not a real EV charging station. Though the relay box may be a complication.
The cord is the charger, though. There are just two home charger styles: the “wall connector” and the “mobile charger”. The wall connector is hardwired and can charge at 60A or so. The mobile charger is limited to 32A and has a variety of pigtails to change the plug style (from a standard 120v plug to a 14-50).
Since the wall charger is massive overkill in any case, the plan is to just use the mobile charger. I haven’t decided whether to buy a second one or not–if I do, it would just be for the convenience of not having to take it down from the wall and roll it up every time I go on a longer trip. But regardless, I’d be using the same “cord” for both home and away charging (when a real EV station is not available).
NEMA 10 is not permitted for new installations. it was OK back in the past, but because appliances using it (e.g. dryers and ranges) tied the neutral leg to the chassis they could be a shock hazard from a fault in the neutral leg and a poor bond to safety ground at the panel. NEMA 6 is safer; the third pin is safety and the neutral leg likely isn’t even required anyway for an EV charger, current flows between hot and hot’. Plus an EV charger isn’t going to have a metallic chassis to present a potential shock hazard.
Thanks for the confirmation–that was pretty much what I guessed although I didn’t realize NEMA 10 was outright not permitted for new installations (Wikipedia just says it’s “deprecated”, which is a little ambiguous).
The neutral would only be necessary if the device needed a single 120v leg for some purpose or other; an EV charger clearly doesn’t need this. A 6-50 sounds like the right choice. A 6-30 would be even better since it wouldn’t require fiddling with the current settings on the car, but Tesla doesn’t have an adapter for 6-30; just 6-20 and 6-50.