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Advice: NEMA 14-50 or Wall Charger

I'm confused. There should be no need to replace any breakers or replace wire running across the house if you keep within the 30 amp budget at the subpanel. I checked the subpanel and I >still< can't figure out why they'd put a 30 amp duplex breaker in there, presumably backfeeding the panel.

If the wire running from the main to the sub can accommodate 40 or 50 amps, you could get the breaker in the main panel upgraded and properly connect the subpanel(to the lugs meant for this very purpose), and then repurpose the now-useless 30 amp duplex breaker(or at least its breaker-spots) in the subpanel for your HPWC(if you want).
The previous owner of the house expanded & remodel back in mid-2000, so I wasn't sure what wires they put in or the reason for 30 amp duplex breaker in sub panel.

I guess the few quotes I got Tesla referred electricians probably want a bigger job and thus recommending to go full 40 or 50 amps charging, and they only way to accomplish that is do draw power directly from main panel (with new wiring etc.)


Active Member
Aug 8, 2021
SF Bay Area
That subpanel is rated to carry 100A.
Ah, now I see it in the photo. I wonder why it's only using a 30A breaker. OP may be able to expand the panel using tandem breakers and expand the capacity by swapping the breaker if the wiring can support it. Or if both panels are in or near an unfinished garage, it shouldn't cost too much to run a new wire from the main panel to the subpanel that can actually carry 100A.


Active Member
Jun 12, 2018
palo alto, ca
I installed a 14-50, that way I can use it for other things.

And bought this cable, which can do 40A as opposed 32A for the standard mobile connector:

I bought it on eBay as Tesla didn't have it in stock.
I ended up doing the same here.. didn’t have a clean 14-50 at time of purchase so I added another to my current 50+ year old breaker box, so 30A was all it would muster without more upgrades.

At the time, I picked up a 2nd mobile connector for $199 just for home charging. Keeping the main delivered one with the car for travel (although I didn’t really need it).

On the peninsula I found an electrician who put in the 14-50 for $395, that was three years ago, so it’s probably more. CL has many who do this type of work.

Personally, I would not spend 2000-3000 for anything like this and certainly not anything one OEM specific unless I was just really price insensitive. Which I guess I am, but still think frugally.

As for charging, getting 30 mph charging vs 40 mph charging wasn’t a big deal for me and my use case.. with better charging scheduling these days (vs. three years ago) it’s pretty easy to get all one needs at low rates and high confidence.
It looks like you have 4 20A circuits in the garage. What are they all used for? You mention garage door opener, lights, and outlets. All of that could probably be on one circuit.

You can use a NEMA 6-20 outlet (20A, 240V) and get up to 15 miles/hour charging. Depending on your use that may be all you need and would require minimal work.

My advice:
First, see what you actually need in your garage. If you can make it with the 30A sub panel, then just add a 20A-240V circuit for you car and be done. This will be the quickest and cheapest option. If you figure out later on you need faster charging then you’re not out that much, either.

If you need more than that, check to see if you have available capacity in your main service panel at the house. Assuming that’s the case you can get an estimate to run larger wires to the garage to upgrade the capacity of your sub panel. At this point it makes sense to run wires for a 100A sub panel if possible. The wire will be a bit more expensive but you’ll be more future-proofed.

As far as what kind of charger to use, if you are going to be mounting it outside the wall connector is your best option. It’s designed to be exposed to the elements and you won’t have the added issues with a receptacle. If you’re going to be using it inside the wall connector is still the best option but you can use the mobile connector. Note that the mobile connector requires a GFCI protected receptacle which can add an extra $100+ depending on the size. The larger amperage receptacles need to be good quality and aren’t cheap, either.


Active Member
Feb 3, 2021
What's the capacity of the subpanel? Note that it's possible to "derate" a subpanel by using a smaller wire that can't carry the full capacity of the subpanel -- as long as you use a smaller breaker to feed the smaller wire and thus protect it from overheating. If it's a 50A or 75A or 100A subpanel, you might be able to upgrade the capacity of the existing panel by just changing out the wire and the breaker.
This is the direction I would look to go. Upgrade the sub panel and then have a hard wired wall connector installed so you can eliminate the plug and GFCI breaker requirements.

Assuming you have 200 amp service why not go with a 60 amp so you can charge at the full 48 amps?
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Updates - I have another contractor who came over tonight and check out the panels. Initial feedback is, it should be okay with the 30amp sub panel and wall charger, just need to work out a few connections with the few 20amp breaker sets. However, he uploaded the pictures to his supervisor and his supervisor says it's not gonna get through the city inspection. So their solution is the same as previous few - upgrade a 50amp breaker in the main pane, pull a new long wires from the main panel to the exterior with either 14-50 or WC directly.
Need advice on whether I should go with a NEMA 14-50 or directly a WC. I live in the bay area, made a few quotes with the tesla recommended electrician and they came back from $1600 to $3000 (pretty crazy), with a permit.

Here's my situation:
1. The subpanel in the detached garage is not strong enough (30 amp, I think), so all of the electricians suggest installing a new wire directly from the main panel and running across the house (~70 ft).
2. Install/upgrade the 40amp circuit breaker in the main panel
3. NEMA plug with exterior rainproof enclosure.

Do you think approx. $2000 is a fair quote for this project? Should I just go directly with a Wall Charger instead? (Probably saving $ from the NEMA outlet, enclosure, and Mobile Connector)
I paid $400 for the Tesla WC in May of 2022
I hired a local (pro) certified, retired electrician for installation. He charged $900 (labor and parts which consist of approx 50ft of approved wires and (2) 30A breakers which are compatible with my existing 200A breaker. He did a beautiful job. Just pay and never look back
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I paid $400 for the Tesla WC in May of 2022
I hired a local (pro) certified, retired electrician for installation. He charged $900 (labor and parts which consist of approx 50ft of approved wires and (2) 30A breakers which are compatible with my existing 200A breaker. He did a beautiful job. Just pay and never look back
just curious, since you're putting in new wires and breakers, why didn't you go with a higher amp breaker like 50amp or 60amp to fully utilize the wall charger?
Ya... that's not a 60 amp circuit. That's a 30 amp circuit, which allows for 24 amp charging. Previous poster was asking if you are doing all that work, why not run at least a 60 amp circuit.
I am not a certified electrician, HE is. He installed 10+ for Tesla cars around here and customers are very happy with his work
What do I know? ZERO in this area, but reviews from his customers are good enough for me. They all get 48amp charging with (2) 30amp breakers

This is what he used ... sorry about my terminology, as I said I know ZERO about electrical circuit


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