Pre Wire For Future Car Chargers

[Knuckle Dragger]

But that doesn’t allow you to downsize the branch circuit. Per 625.42, in order to use a branch circuit less than the maximum EVSE rating, it must be limited by a hardware setting not easily accessible to the user.

There is also an allowance to use a software limit, but it must be password protected with the password only available to qualified personnel. But I can’t imagine this in a residential installation.

What it allows the car owner to do is program the EV to draw what is allowed for the that particular branch circuit that is installed.
If it's a 50amp rated branch circuit program to draw 40 amps.

 

[Fred B]

What it allows the car owner to do is program the EV to draw what is allowed for the that particular branch circuit that is installed.
If it's a 50amp rated branch circuit program to draw 40 amps.

Same as the fuse box "allowed" the HO to put a 30A fuse onto the 20A circuit. (That never happened).
Home owner REALLY most time has no clue as to max allowable circuit draw for a particular conductor size or equipment5. "If 40A gets my car charged in X hrs then using the 50A setting will get it charged even faster. So I'll just dial it up to 50A." That is what would happen if the car owner was allowed to control output settings. (How long would the 48A charger load run before it trips a 40A breaker or how long would the undersized 40A conductors remain in tact an not begin to fail, I don't know.)
If settings was only in the control of the installing electrician and the car/home owner had no access or ability to make a change once electrician made the settings, your suggestion of the adjustable EV charger and undersized (compared to max draw of EV charger) could work. I believe the automation or adjustments of Amperage settings was related to the EV demand itself, not to the system circuit wiring.
My preference when HO says they "might want" or "will want an EV charger" but doesn't know yet what they will be getting, is to only install a wiring system that would allow me to pull in wires at a later date. Once they know what they are getting.

 

[readydave8]

Well, that's a first for me.

Me too, pic came from Angie in older thread

 

[retirede]

What it allows the car owner to do is program the EV to draw what is allowed for the that particular branch circuit that is installed.
If it's a 50amp rated branch circuit program to draw 40 amps.

I understand that.

My point is that the code does not allow an installation that permits the user to select a charge rate that would exceed the circuit ampacity.

 

[wwhitney]

But that doesn’t allow you to downsize the branch circuit. Per 625.42, in order to use a branch circuit less than the maximum EVSE rating, it must be limited by a hardware setting not easily accessible to the user.

FWIW, I hadn't heard of that, which turned out to be because that language in 625.42 is new to the 2020 NEC.

Cheers, Wayne

 

[Knuckle Dragger]

I understand that.

My point is that the code does not allow an installation that permits the user to select a charge rate that would exceed the circuit ampacity.

I get it.
My point.
The op was trying to wire for a future EV and I was pointing out that it could be adjusted to function properly and safely if programmed according.
That being said.
Then we cannot truly wire for future EV because you don't know what will be tied into it.
It would be a the luck of the draw.

 

[retirede]

……that language in 625.42 is new to the 2020 NEC.

Cheers, Wayne

Yeah, it would have been helpful if I’d mentioned that originally.

 

[gadfly56]

I get it.
My point.
The op was trying to wire for a future EV and I was pointing out that it could be adjusted to function properly and safely if programmed according.
That being said.
Then we cannot truly wire for future EV because you don't know what will be tied into it.
It would be a the luck of the draw.

If you wired to a junction box and sized the cable and OCPD for continuous use you should be good, as pointed out above. I don't know if I'd trust a pull string to remain in place for a year or three waiting for that future install.