Wall Connector Installation

[Runt8]

(I apologize if this is the wrong forum for this - I didn't see any other forums that would be a better match. Mods - feel free to move it if it belongs elsewhere)

I've been researching options for installing the Tesla Wall Connector in my garage. I realize that a lot of people opt to install a 14-50 (or similar) outlet, but I have several reasons for opting for the wall connector instead. Here's some information about my situation:

1. My main panel is on the outside of my garage. I have 200 amp service, and I've estimated my current demand load at around 105 amps, based on the square footage of my house and the major electrical appliances. So, I don't think using a 60 amp circuit is going to be a problem in terms of overloading my service.
2. Currently, my main panel has 20 spaces, and 19 of them are filled - 4 double-pole breakers (8 spaces), 3 single pole breakers wth test buttons (for GFI circuits?), and 8 tandem breakers.
3. There is a 100 amp sub-panel in the basement that is almost empty - it has 2 20 amp circuits (1 unused, and one powering a single outlet meant for a freezer that is currently only powering a wireless router, which could easily be moved), and 2 15 amp circuits (one for basement outlets, one for basement lights). There are something like 12 empty spaces.
4. I plan on pulling permits and getting it inspected, and using an electrician for the "delicate" work (i.e., the hookups). My town uses NEC 2014 electrical codes, so I want to be compliant with that. However, I am an avid "do-it-yourselfer" and I would like to plan it out and do as much of the work as I can by myself.

A few questions:
1. It appears that the wall connector will accommodate multiple amperage levels, is this correct? My install would either be a 30, 50, or 60 amp circuit.
2. As far as I can tell, I am unable free up an additional space in my main panel (unless I can double up two of the breakers with the test buttons). And without two adjacent spaces, I'm unable to get 220 regardless of the amperage I decide to go with.
3. It appears as though I have power to spare from the sub-panel. Are there any problems with running a line from the basement panel to the garage?
4. In terms of ease of installation, running a circuit from the main panel would be relatively straightforward - out of the panel, through the wall to the inside of the garage, and up a few feet to where I want to mount the wall connector. Trying to route a cable from the basement, and dealing with code issues related to going through/under joists, around HVAC ducts, etc, seems like a prettty big hassle. Does it make more sense to upgrade my main panel (or add a sub-panel right next to it), or try to use the available space in the basement sub-panel?

Hopefully my rambling makes some sense and thanks for any suggestions!

 

[rnelsonee]

1. Yes, but so will any wall connector - current flows through a wire according to the demand and the conductance of the wire. Installing a 14-50 outlet, for example, means 50A breaker, which means 40A max load (max load is 80% of breaker by law). So long as the Model 3 charger goes up to 40A, 14-50 is good. If the Model 3 goes to 48A as the latest Model S and Model X's run, then yeah, you would benefit from a 50A connection.

2. Some panels allow more tandem breakers - check the diagram. But yeah, sounds like you're pretty maxed out.

3. Nah - you'll just need more wire, and therefore thicker wire.

4. I'd work on the main, yeah, only because it's so over-used It's probably cheaper and you're still not 100% sure what the subpanel can even get from the main (what's the gauge/distance from main to sub, for example)?

 

[Saghost]

The only one of these I know much about is #1. Yes, the current generation HPWC has a rotary dial inside that has 16 settings to allow it to be dialled from 12A available on a 15A circuit all the way to 80A available on a 100A circuit.

 

[Runt8]

2. Some panels allow more tandem breakers - check the diagram. But yeah, sounds like you're pretty maxed out.

I actually can have more tandem breakers, but the only ones that aren't already tandem are either double post or the single post with the test buttons (which I think are GFI breakers). So the question is whether or not I can switch two of those to be tandem.

4. I'd work on the main, yeah, only because it's so over-used It's probably cheaper and you're still not 100% sure what the subpanel can even get from the main (what's the gauge/distance from main to sub, for example)?

The sub is on a 100 amp breaker, and is using what looks like 2 gauge wire (I'm no where near an expert, but it's definitely thicker than 6 gauge). I can look closer and see if it's specified if it becomes important. The run is only about 30' max (probably a little shorter). I'm thinking there's pulling 60 amps from there wouldn't be a problem, but I guess I'd have to consult with an electrician to be sure.

The only one of these I know much about is #1. Yes, the current generation HPWC has a rotary dial inside that has 16 settings to allow it to be dialled from 12A available on a 15A circuit all the way to 80A available on a 100A circuit.

Thank you for verifying this!

 

[Runt8]

It actually appears the the three breakers with the test buttons are arc fault breakers. They are going to the bedrooms upstairs.

 

[Runt8]

Just had a thought - is it possible to convert the subpanel to 120 instead of 240 (preferable using the existing wiring)? That way I would free up a second space in the main breaker box for the wall charger. As I mentioned before, the subpanel is almost completely unused; no reason I need 100a 240v down there.

 

[Craig-Tx]

Sounds like your builder did a very nice thing by adding the generous sub panel in the basement. But they did a horrible injustice by getting the bare minimum for your main panel. I really wish there was a NEC code requiring a minimum amount of expandability in a new panel.

You *might* be able to do what you suggest by dropping one leg of the basement subpanel, But that would be an unusual configuration. I'd recommend against it as it would lead to confusion in the future.

Would it be possible to move one or two of the existing circuits to the basement sub panel?

Otherwise, I'd look into biting the cost on changing out the main panel for a reasonably sized main panel. Or possibly putting a sub panel right next to the main panel, but you would have to move a circuit or two over to the new sub panel.

I don't believe there are any tandem AFCI breakers, and even if there were, you would have to make sure you don't exceed the circuit limit rating of the main panel. It's possible it can only support up to 28 circuits if using tandems (as you are now.) That limit should be marked inside the panel.

 

[Runt8]

Hi Craig,

Thanks for the response!

It might be feasible to move the range down to the basement sub panel - if I remember correctly the line for it is run between the joists in the basement, so re-routing it shouldn't be a big deal. That would also be nice because it frees up a 50a 240v circuit in the main panel, so I wouldn't have to re-arrange any of the other breakers to get two adjoining slots or to fix load balancing issues.

 

[Rocky_H]

I actually can have more tandem breakers, but the only ones that aren't already tandem are either double post or the single post with the test buttons (which I think are GFI breakers). So the question is whether or not I can switch two of those to be tandem.

A lot of people know about the tandem ones that put together two of the 120V circuits, but for the two-pole 240V ones, those can be merged together too. It's called a "nested breaker" and fits in the space of a regular two-pole breaker. Some panels can take those. Here's a really basic diagram:
A
B
B
A
The two switches in the middle are connected and are one 240V circuit, and then the two on the outside are connected together and are a different 240V circuit. You can buy those breakers in various combinations of current values, so maybe a 30/50 or a 40/50. See if you can take those, and you might be able to combine two and free up a two-pole space.

 

[Runt8]

A lot of people know about the tandem ones that put together two of the 120V circuits, but for the two-pole 240V ones, those can be merged together too. It's called a "nested breaker" and fits in the space of a regular two-pole breaker. Some panels can take those. Here's a really basic diagram:
A
B
B
A
The two switches in the middle are connected and are one 240V circuit, and then the two on the outside are connected together and are a different 240V circuit. You can buy those breakers in various combinations of current values, so maybe a 30/50 or a 40/50. See if you can take those, and you might be able to combine two and free up a two-pole space.

I've got a Square D All-In-One panel (RC2040M200CH, if that matters). Do you happen to have a link to one of these nested breakers? Did a quick search but the only place I came across that term was in forums related to EV car charging

Thanks!

 

[miimura]

Google Image search turned up this example

 

[Runt8]

Thanks for the picture. I talked to an electrician, they call these breakers a quad tandem breaker. He had never heard of the term "nested breaker."

Square D Homeline 2-20 Amp Single-Pole 1-30 Amp Two-Pole Quad Tandem Circuit Breaker-HOMT2020230CP - The Home Depot

 

[Rocky_H]

Oh, sure, "quad" was the term I was forgetting. Quad/tandem is actually different than I had seen before. The "tandem" part is that there are two separate single pole breakers in there. A regular quad breaker would have just two two pole ones.

 

[Runt8]

Oh, sure, "quad" was the term I was forgetting. Quad/tandem is actually different than I had seen before. The "tandem" part is that there are two separate single pole breakers in there. A regular quad breaker would have just two two pole ones.

But either way, you put me on the right path, so thanks again!