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Tesla wall connector question.

Darthbenji

Active Member
Mar 27, 2018
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594
Ontario
Just had mine installed today. Get the car Thursday. Is the green light on the wall connector always supposed to be on? Also, can I dial down the amps it draws as it’s supposed to be adjustable or is it once installed it’s set to what it’s set to?
 

Darthbenji

Active Member
Mar 27, 2018
1,003
594
Ontario
I’m asking because I’m not sure how the electrical aspect works. If it’s a 48 amp circuit on a 60 amp breaker, and I set to charge at say 32, is it pulling 48 but only using 32 or does it only pull what I’m actually using. I’m more wondering about overall load.
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,660
7,951
Boise, ID
You set the switch inside it to match what the actual circuit is that it's installed on. The owner's manual that comes with it shows you what that switch should be set to. That is a set it once and forget it thing that you never need to touch again. That sets the total capacity available.
Then, the car will draw whatever it needs to.
 

P85_DA

Supporting Member
Supporting Member
Apr 25, 2015
4,219
2,950
CA
I’m asking because I’m not sure how the electrical aspect works. If it’s a 48 amp circuit on a 60 amp breaker, and I set to charge at say 32, is it pulling 48 but only using 32 or does it only pull what I’m actually using. I’m more wondering about overall load.

It’s pullin what you set car at ..in your case you set 32 so pulling 32
 

Saghost

Well-Known Member
Oct 9, 2013
8,217
7,010
Delaware
I’m asking because I’m not sure how the electrical aspect works. If it’s a 48 amp circuit on a 60 amp breaker, and I set to charge at say 32, is it pulling 48 but only using 32 or does it only pull what I’m actually using. I’m more wondering about overall load.

The HPWC is basically just a smart switch. It passes line power on to the car, along with a signal telling the car how much it is permitted to pull (the signal for how much the car is allowed to pull is set by a rotary switch inside the HPWC, which the installer should have set to match the wiring it's connected to.) The HPWC isn't consuming or transforming any of the power (beyond a trivial amount for its processor and to cycle the relays.)

The car puts a load on the system based on the settings in the car, respecting the limit the HPWC passed it. If the car sees a higher voltage drop when it loads the circuit up, it'll reduce the current it is drawing to hopefully prevent heat buildup elsewhere from becoming dangerous.
 
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markb1

Active Member
Feb 17, 2012
3,054
662
San Diego, CA
I’m asking because I’m not sure how the electrical aspect works. If it’s a 48 amp circuit on a 60 amp breaker, and I set to charge at say 32, is it pulling 48 but only using 32 or does it only pull what I’m actually using. I’m more wondering about overall load.

“Pulling” and “using” are the same thing to me, when it comes to electrical current. The dial inside the wall connector sets the max, and the car’s onboard charger pulls what it needs, up to the max communicated from the wall connector, but also not more than you configure in the car.
 
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Darthbenji

Active Member
Mar 27, 2018
1,003
594
Ontario
Any way to tell if the installer set the dial to 48 before plugging the car in? It was his first Tesla install and while he seemed entirely competent I’d rather not worry it’s set at higher.
 

Saghost

Well-Known Member
Oct 9, 2013
8,217
7,010
Delaware
Any way to tell if the installer set the dial to 48 before plugging the car in? It was his first Tesla install and while he seemed entirely competent I’d rather not worry it’s set at higher.

Nothing simple. I think there are three options: Plug in a car that can do more than 48A and see what the car reports the limit at, pull the front panel and check the position of the rotary dial, or use an O-Scope and probe to determine the duty cycle on the pilot signal and compare to J1772 standards.
 

Darthbenji

Active Member
Mar 27, 2018
1,003
594
Ontario
C877F32C-CFE1-42FB-A562-8F2BEEEE8EA7.jpeg
Ok. I’ll maybe pull the front off.

I wasn’t here when it was installed. Any issue this part wasn’t used?
Sorry for the neurosis.
 

PoitNarf

My dog's breath smells like dog food
Jun 7, 2016
2,870
4,011
NJ

Yep, looks like your electrician installed a disconnect for the wall connector. My guy did the same. Just cut the power to the wall connector and take the top cover off to see what the dial is set to. As others have mentioned the wall connector should be set to the amps for the circuit it’s connected to. You should definitely read the manual.
 
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eprosenx

Active Member
May 30, 2018
2,074
2,517
Beaverton, OR
Interesting. I am not sure why the disconnect was required. I do not know of any NEC requirement for this, though your local jurisdiction may have additional rules.

As others have said, the easiest way to check is to take the cover off and look at the rotary dial setting and compare it to the table in the manual which tells you what the different positions mean. It only sets what it will "tell" the car is the max it can support. You can then also tell the car from the dashboard touchscreen to use even less than that if you want to. And the car can and will often draw less than either of those numbers if it is ramping up the charge slowly or the battery is nearing capacity...

Note that you need the "security torx" head screwdriver bits to take the cover off. There is one screw on the bottom and then some careful prying of the plastic cover required, plus then about 8-12 additional torx screws to take off. Just be careful not to mess up the rubber seal under that layer of plastic since it is the waterproofing. Make sure it is re-seated properly when you re-install.

Feel free to take detailed pictures of what you see and we can take a look to see how good the install was. ;-) I would also be interested to see what the inside of that disconnect switch looks like (make sure the metal box was bonded to ground). Shut off the breaker inside of course before tearing open the disconnect switch.

I just installed my wall connector for my upcoming M3 just a couple weeks ago myself so I am well versed in this. ;-)

P.S. If indeed this is on a 60 amp breaker and the wire is sufficiently sized and the disconnect does not have fuses smaller than 60 amps and you are going to be only using this with a Model 3 then there is no way the car can pull more than 48 amps (which is the 80% derate for a 60a breaker) so you won't have any issues even if the dial is set wrong (well, I guess if it is set too low it might charge slowly). But kudos to you for wanting to check - and I think it is a GOOD idea to make sure it was done properly. It is always wise to have electrical equipment installed fully correctly. If you later upgraded to a Tesla with a faster charger (like a Model S with the bigger charger) - or if a later homeowner bought a car that could charge faster - then they may run into this kind of "latent defect".
 

eprosenx

Active Member
May 30, 2018
2,074
2,517
Beaverton, OR
Interesting. I am not sure why the disconnect was required. I do not know of any NEC requirement for this, though your local jurisdiction may have additional rules.

So I did some more research into this and I found a new section of the NEC I was not aware of. Section 625.

Among other interesting tidbits, it has this:

625.43 - "Disconnecting means - For equipment rated more than 60 amperes or more than 150 volts to ground, the disconnecting means shall be provided and installed in a readily accessible location. The disconnecting means shall be lockable open in accordance with 110.25."

I read that as you can put one of those wire cage covers on the breaker so it can be locked "off" (they cost a few bucks at Home Depot or Platt Electric), but I think this could very much be open to debate as to what type of disconnect they are asking for. I guess it all comes down to your AHJ (authority having jurisdiction). I suppose if your breaker panel is a long way away or not easily accessible I could see the local inspectors wanting a disconnect right next to the unit.

Really though I think it is pretty silly. There are no serviceable parts inside like there are with AC units. If it breaks, you have to replace the whole thing anyway... (and that should nearly never happen) So the value prop of a disconnect switch is dubious in my opinion for most residential installs.
 
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brkaus

Well-Known Member
Jul 8, 2014
8,025
6,508
Austin, TX
I have a disconnect and mine is 50a. He said it wasn’t required, but it’s one of those AC disconnects that you pull out the blade part. They are about $10, so why not.

I don’t see 624.43 would apply. It’s 60a and 120v to ground for each phase.
 
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