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Installing Tesla Wall Charger, need future proofing advice on wiring

matt.mcg

New Member
May 17, 2020
2
0
San Ramon, CA
Hi there, I'm a noob here with the recent addition of a Model Y to the family. Wife love the car and is having fun learning the vehicle.

I'm about ready to have an electrician come out to install our Tesla Wall Charger. We will be running wire from the garage panel within the walls to a spot on the wall about 15 feet away (total line run). I know the typical install for this is 6GA wire but I am looking to future proof the install so that it can support increased amperage in the future. My assumption is that battery capacity and charging speeds are only going to increase, so want to overbuild it now to accommodate for the future. I can see where 48A (on a 60A circuit) will increase to 64A (on a 80A circuit) and further increase to 80A (on a 100A circuit).

I'm not an electrician as you can see but would appreciate the thoughts and guidance from folks that have faced this decision.

If I understand correctly:
4GA can support up to 70A (at 140 degrees F)
3GA can support up to 85A (at 140 degrees F)
2GA can support up to 95A (at 140 degrees F)

So it would seem that I should be looking at 4GA minimum and preferably 3GA or 2GA to support up to a 100A circuit.

I'm sure there is a lot more to it but would appreciate your opinions! Thanks in advance!
 

empiredown

Member
Mar 27, 2020
418
400
78642
Was in a kinda similar situation to you a few months ago... My wife, too, loves her car. I would consider a couple other things as I did...

- Do you really need to charge anything faster than 48-50 mph? Is it worth the stress you are putting on your other infrastructure? Unless this is a completely dedicated circuit, your house will also be drawing on it as well, so you risk "browning" yourself out or even a fire if (big if, granted) you over do it, your other components aren't up to the task, your boxes and other infrastructure are not optimal, ventilated, etc. Separately, while not stressing it to SC levels, faster charging does have an impact to the battery cell with heat stress, etc. So, the slower/longer you can charge, generally, is better and you let the car and its brain figure out the best way to accomplish that.

- Yes, you will be paying for your power consumption, but do you really need to tax the system just because you want "more". You also live in Kalifornia (I escaped when I was 18 and haven't looked back...). Just because something can happen, doesn't mean it can or will. Your State has a way of intervening and not allowing it to. Very possible that the current levels are the max "allowable limit" that will strike a good balance between what people are comfortable with and what is tolerated in stressing the system. Tesla has factored that in. Just a guess...

It is one thing to make sure your wall charger and associated wiring is capable, but you also have to take into account the whole package and the impact this part will have on it. All that said, you've done your homework and know what you want. Heavier wiring is a good safety factor on the current system and its constraints anyway, so peace of mind. You then have future flexibility if/when it can be realized.

Good luck!

SS
 
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frankvb

Member
Supporting Member
Feb 29, 2020
930
578
San Diego, CA
Considering you would mainly be charging overnight, I don't see that much advantage of going higher than 48A sustained (currently the maximum with a wall charger). In 6 hours that would be nearly 70kWh. Of course if the price difference is limited it could be worth putting in 4 AWG instead of 6 AWG.
 

Msjulie

Active Member
Jun 26, 2016
2,449
1,809
Monterey Peninsula
Well we just rewired a garage with a nema 14-50 outlet but because we did a minimal future proof, the wiring can handle whatever would be the 100 outlet in some future day

Cheap insurance and I hope to be at this place a Long Time so why not.
 

MY-Y

Active Member
Mar 4, 2020
1,127
1,267
MD
There is a limit on how big a wire you can connect depending on the device. A 60 amp breaker won't take a 2 gauge wire. I don't know the limit of the Tesla HPWC lugs, probably 3 or 4 gauge. I'm planning on running a 4 gauge.
 

Jeff3820

Member
Aug 1, 2019
85
64
Wisconsin
The gen 3 wall charger is limited to a 60A line/48 A maximum draw...no need to add more current capability as the wall charger can't use it. The Tesla wall charger only uses two hot lines and a ground. To help in future proofing you might ask the electrician to add an extra 6 gauge line for a neutral. This neutral line does not have to be connected at the breaker box or the wall charger but is just present for the future...if you ever want to change the wall charger (you move and want to take the wall charger with you...or you sell the Tesla) for a NEMA 14-50 outlet the neutral line will be needed. So just by changing the breaker to a 50 A breaker and hooking up the neutral wire a NEMA 14-50 can be installed in place of the wall charger. No added labor for the electrician but you can change to a different outlet without pulling wire.
 

matt.mcg

New Member
May 17, 2020
2
0
San Ramon, CA
Ok thanks for the advice! Very helpful!

Sounds like I should stick to this configuration to future proof as much as possible:
-Use 4AWG wire with 4 leads (to accommodate conversion back to NEMA 14-50 if needed)
-60A circuit breaker on the Tesla Wall Charger
 

1965Falcon

Member
Supporting Member
Oct 10, 2019
112
200
Vancouver, WA
If you really want to future proof then just install a 100 amp sub-panel (assuming you have 100 amps available) at the location of your wall charger. Install 1 1/4" conduit from the sub-panel to the junction box that you hook the wall charger too (next to your subpanel) then you just can run different wire if needed in the future and up the breaker right there. Would add some $$$ to your install though.
 
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azjohn

Member
Oct 12, 2018
332
208
Virginia
The charger is actually inside the car and the HPWC only delivers electricity to the car, the charger wont charge over 48 amps
 

animorph

Active Member
Apr 1, 2016
2,161
1,584
Scottsdale, AZ
I used 2 AWG and shared one 100A circuit for two Gen 2 HPWC's. The Gen 3's share differently (if they even do it yet), so I'm not sure using wire good for 100A does a lot for you now except to run to a subpanel. We can charge the X at a max of 72A, or both cars at 40A each. Having two HPWC's is convenient. We installed one connector at first, but the wiring and an extra junction box were ready to add the second connector. We added the second connector a little over a year later.

Batteries may get bigger, but efficiencies should get better as well. I think 32A or whatever, overnight, should be fine for 99% of the time. Even if it doesn't completely fill a new Roadster battery from empty to full overnight, do you really need that many miles? I don't think I'd worry about faster charging as much as adequate charging for all vehicles. I'd be fine if I arrived at 5% charge with my Roadster and it filled to 60% the first night and 80% the next.
 
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user212_nr

Active Member
Aug 26, 2019
1,407
875
US
We will be running wire from the garage panel within the walls to a spot on the wall about 15 feet away (total line run).

I know the typical install for this is 6GA wire but I am looking to future proof the install so that it can support increased amperage in the future.

You are mistaken about this. The trend has been toward lower amperage for home charging. In the past, Tesla offered 80A (derated 100A, I think), and now only 60A.

If you have 2 cars (most families have 2+ cars) with 60A of power, that is more than 50% of the home's power capacity, at minimum. Besides, if Tesla cars can get 600 mile range, that doesn't mean that you will be driving 600 miles every day!

If you want to future-proof, have the electrician run a second wire for a second car (2 car garage?). Use the wires for 60A but install a NEMA 14-50. That way, you can plug in a second car, but also can also upgrade it in the future. Or install one outdoors.
 
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1965Falcon

Member
Supporting Member
Oct 10, 2019
112
200
Vancouver, WA
If you have 2 cars (most families have 2+ cars) with 60A of power, that is more than 50% of the home's power capacity, at minimum. .

This totally depends on the amperage rating of your main panel. While if it was an older or smaller house with a 100 amp service you'd be correct, however modern homes rarely have anything less than 200 amps, and I see a lot of homes with two 200 amp services. Just depends on what type of heat/cooling and appliances you have.
 

user212_nr

Active Member
Aug 26, 2019
1,407
875
US
This totally depends on the amperage rating of your main panel. While if it was an older or smaller house with a 100 amp service you'd be correct, however modern homes rarely have anything less than 200 amps, and I see a lot of homes with two 200 amp services. Just depends on what type of heat/cooling and appliances you have.

2 cars with 60A of power = 120A, which is greater than 50% of 200A. Add a third car at 60A and there is no power left.

That is why it is unreasonable to think that cars will be coming with giant 100a chargers.
 
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pdx_m3s

Active Member
May 18, 2019
1,393
1,254
Portland, OR
If anything, I see it going to other way, with cars drawing less power (or the same) to charge in the future. Future proofing to me would be provisioning for a second charger on the other side of the garage.
 
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1965Falcon

Member
Supporting Member
Oct 10, 2019
112
200
Vancouver, WA
2 cars with 60A of power = 120A, which is greater than 50% of 200A. Add a third car at 60A and there is no power left.

That is why it is unreasonable to think that cars will be coming with giant 100a chargers.

Ah, I missed the two car part. I stand corrected... Not to change the topic from the OP but I keep expecting more stores/businesses to start having destination type chargers. I think eventually this will happen where you just plug in wherever you are and it drops the need for home charging down. Most of the projects I work on now we are laying the conduit for chargers, but not installing the chargers themselves. I think once the demand starts increasing and other businesses offer free charging, more will follow suit.
 

Rocky_H

Well-Known Member
Feb 19, 2015
7,070
8,685
Boise, ID
My assumption is that battery capacity and charging speeds are only going to increase, so want to overbuild it now to accommodate for the future.
People tend to be in that mindset because they are thinking of computers or smart phones. But that paradigm doesn't apply to this situation with recharging a car, so it's coming out wrong.

You need to refill however many miles you drive. And you drive however much you drive. The capabilities of the car are unrelated to that. If the capabilities of the cars get better, that does not mean you magically live 2X, 3X, 4X, or 5X as far away from where you work. You still need to refill the same amount of miles overnight, whether the car has 300 miles of range or 1,000. What usefulness is there in refilling several hundred miles overnight?

I can see where 48A (on a 60A circuit) will increase to 64A (on a 80A circuit) and further increase to 80A (on a 100A circuit).
But you have not been following the history of Tesla long enough to know that they have only been trending in the opposite direction and going lower and lower and lower with their charging speeds.
The highest charging speed used to be 80A, and then it was 72, and now it's 48. And where the wall connectors used to be made to offer that high power with 80A on a 100A circuit, now, they have redesigned the wall connectors so they are smaller and lower power and can't use anything more than a 60A circuit. So they are definitely going toward the trend of lower power charging for the future.
 

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