Gen 3 Wall Connector install

[papai.08]

Hi,

The house came with a 40amp breaker on a 8/3 wire. This is terrminated at the garage in a junction box. My question is, do I still need an electrician to install the charger or is it just a mayter of hooking up the wires to the correct terminals?

 

[E90alex]

If you are comfortable with wiring then you can do it yourself since the hard part is already done.

You likely will need to splice/extend the wires from that junction box in order to have enough length to run it properly to the terminals inside the wall connector.

 

[papai.08]

If you are comfortable with wiring then you can do it yourself since the hard part is already done.

You likely will need to splice/extend the wires from that junction box in order to have enough length to run it properly to the terminals inside the wall connector.

Thanks! What amperage should I set the charger at?

 

[brkaus]

40a breaker / 32a charging. And I’m 99% sure the 8ga nm-b is approved for that.

 

[E90alex]

Thanks! What amperage should I set the charger at?

Your breaker is 40 amp so 40 amp.

 

[MattM24]

Is there extra wire in the wall that can be pulled out from in the wall? I ask because I’m not sure that extending wires a short distance is a good idea.
As always, make sure to get an electrical permit.

 

[rogersmj]

Yeah you're going to have to extend those wires — they're physically not going to be long enough to install the wall charger unless there's a bunch of slack in the wall. You'll have to use that existing junction box to make connections and have 1 ft segment or so just to go into the wall charger. Just make sure they're good connections — can't be messing with sloppy wire splices at high amperages.

 

[eskudo12791]

Your breaker is 40 amp so 40 amp.

80% load, not 100%

 

[rogersmj]

80% load, not 100%

I'm not sure what you're trying to say, but if the breaker is 40 amp then you set the breaker size in the wall charger configuration to 40 amp. The charger then handles the 80% load calculation.

 

[Tronguy]

I'm not sure what you're trying to say, but if the breaker is 40 amp then you set the breaker size in the wall charger configuration to 40 amp. The charger then handles the 80% load calculation.

Um. We're in total agreement about the 80% bit, far be it from me to argue.

I happen to have a Gen 2 WC and, for various insane reasons, was reading through the installation manual a couple of days ago. That WC gets its amperages set by rotating a small switch. The table in the manual is very clear: First column is the circuit amperage, second column is the 80% number, for each switch position.
(Fun fact: First entry is for a 100A circuit with 80A for the car. Apparently early Model S's could do that.)

Curious: Does the Gen 3 install/provisioning use a table like that?

 

[rogersmj]

Um. We're in total agreement about the 80% bit, far be it from me to argue.

I happen to have a Gen 2 WC and, for various insane reasons, was reading through the installation manual a couple of days ago. That WC gets its amperages set by rotating a small switch. The table in the manual is very clear: First column is the circuit amperage, second column is the 80% number, for each switch position.
(Fun fact: First entry is for a 100A circuit with 80A for the car. Apparently early Model S's could do that.)

Curious: Does the Gen 3 install/provisioning use a table like that?

With Gen 3 you set the breaker/circuit size in software on its config page. That's it. It then charges at 80% of that.

 

[papai.08]

Yeah you're going to have to extend those wires — they're physically not going to be long enough to install the wall charger unless there's a bunch of slack in the wall. You'll have to use that existing junction box to make connections and have 1 ft segment or so just to go into the wall charger. Just make sure they're good connections — can't be messing with sloppy wire splices at high amperages.

the wires are 7in off the wall. Is that not enough wire to come from back panel?

 

[SteevHD]

I may be mistaken, but if there's not enough length on the 8AWG wire to extend, you could just install a NEMA 14-50 outlet in that box, then run a short plug-in lead to the Gen3 charger outside of the wall. Not sure if that more practical than just relocating the charger a few feet closer to the breaker though.

 

[rogersmj]

the wires are 7in off the wall. Is that not enough wire to come from back panel?

Probably not if you install it correctly -- the wires are supposed to be secured on the right side of the housing and "arc" around to the connection points. There's probably 12-16" of wire inside the charger itself.

 

[SteevHD]

the wires are 7in off the wall. Is that not enough wire to come from back panel?

To do it right, I'd say you need closer to 14" of length to manage them in the charger back properly.

 

[E90alex]

80% load, not 100%

As mentioned, Gen 3 WC you select the breaker size during commissioning, not your desired charge current limit. 40 amp breaker, select 40 amp breaker when commissioning the WC. It will then limit charging to 32 amp.

 

[MattM24]

I may be mistaken, but if there's not enough length on the 8AWG wire to extend, you could just install a NEMA 14-50 outlet in that box, then run a short plug-in lead to the Gen3 charger outside of the wall. Not sure if that more practical than just relocating the charger a few feet closer to the breaker though.

You can’t legally install a cord on a hardwire only device.

Moving the wall connector closer to the breaker is a great idea. OP should do this, if possible.

 

[eskudo12791]

I'm not sure what you're trying to say, but if the breaker is 40 amp then you set the breaker size in the wall charger configuration to 40 amp. The charger then handles the 80% load calculation.

Thats on me, thinking the car will still only charge at 32, 40 amp when commissioning.

 

[brkaus]

I may be mistaken, but if there's not enough length on the 8AWG wire to extend, you could just install a NEMA 14-50 outlet in that box, then run a short plug-in lead to the Gen3 charger outside of the wall. Not sure if that more practical than just relocating the charger a few feet closer to the breaker though.

I’d use Polaris connectors and extend it before I’d put in an outlet with a whip.

 

[SteevHD]

Fair. Yeah, as I thought more about it, I came to the same conclusion. I think I'd just relocate one stud closer to the breaker if possible and do it right (if possible).