Wiring for Level 2 Charger

[terranx]

I believe the disconnect is required for over 60 amps OR over 150 Volts. (This is 240 Volts of course). My breaker panel is not in the garage.

Thanks for the ChargePoint tip....I was actually one of the first to purchase the replacement NACS cable. . (The images from this thread are from the initial installation, at which time there was no NACS cable available or even announced.)

Devil's in the details. You need it for over 150 volts to ground. A split phase 240v is always 120v to ground. If this were being wired to a 277/480v circuit (which the gen 3 wall connector doesn't even support), then a disconnect would be required.

 

[Joey D]

Devil's in the details. You need it for over 150 volts to ground. A split phase 240v is always 120v to ground. If this were being wired to a 277/480v circuit (which the gen 3 wall connector doesn't even support), then a disconnect would be required.

To be clear, in the US (where I am), we are single phase, so required in my case. Correct?

 

[terranx]

To be clear, in the US (where I am), we are single phase, so required in my case. Correct?

Technically "split phase" is single phase with a center tap - which is what US households typically get. For residential power in the US, each leg will be 120v to ground. You can only get 240v by measuring phase to phase.

 

[Joey D]

This is why I am not an electrical engineer (or an electrician).

 

[Cosmacelf]

Devil's in the details. You need it for over 150 volts to ground. A split phase 240v is always 120v to ground. If this were being wired to a 277/480v circuit (which the gen 3 wall connector doesn't even support), then a disconnect would be required.

Thank you thank you thank you. That makes a lot of sense now.

In the US, we do NOT have an electrical system that provides 240V to ground in household circuits. It is described as a split phase system, meaning you have a ground, a neutral, a 120V hot relative to ground, and another 120V hot relative to ground which is 180 degrees out of phase with the first hot. The hots are only 240V relative to each other, and always 120V relative to ground.

So, no disconnect needed if your EVSE uses a 60A breaker or less.

FWIW, Grok gave me the correct info about this, while ChatGPT-4 gave me incorrect info. This exception to allow EVSEs less than 60A to not require a disconnect appeared in the 2017 NEC.

 

[Rocky_H]

For explaining split phase to people, I use the colloquial wording of the two sides being like "Plus 120V" and "Minus 120V", which most people immediately get, although it's note totally scientifically accurate to what's going on.

 

[Joey D]

Just to close the loop on this, the electrician installed a "heavy duty" switch to replace the general duty one. (There is no damage to the EVSE). He re-iterated how often switches and receptacles are failing and recommended that I de-rate the charger. For peace of mind, I'm inclined to agree. I have de-rated to 32 Amps...which is the same power draw that would be permissible on a 40 amp circuit (and same max power draw as the Tesla mobile connector).

I am still considering taking the switch out altogether.

 

[Cosmacelf]

Just to close the loop on this, the electrician installed a "heavy duty" switch to replace the general duty one. (There is no damage to the EVSE). He re-iterated how often switches and receptacles are failing and recommended that I de-rate the charger. For peace of mind, I'm inclined to agree. I have de-rated to 32 Amps...which is the same power draw that would be permissible on a 40 amp circuit (and same max power draw as the Tesla mobile connector).

I am still considering taking the switch out altogether.

View attachment 1022363

That’s…a big box. And now we know why the NEC removed the disconnect requirement for EVSEs 60A or less.