Level 2 from home.

[Maquis]

You're introducing a potential hazard when the next owner (who does not know WTF they are doing) decides they want to charge at full rate, removes the software crutch, and burns up the wire.

It’s limited by a hardware setting, not a “software crutch.” They would have to remove the cover and switch the setting.

The NEC specifically allows installing a hardware-derated EVSE to be installed on a lesser circuit as long as it requires tools to access the switch.

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[Nick503955]

It’s limited by a hardware setting, not a “software crutch.” They would have to remove the cover and switch the setting.

The NEC specifically allows installing a hardware-derated EVSE to be installed on a lesser circuit as long as it requires tools to access the switch.

Tesla's Wall Connector doesn't have a hardware switch. It is a software switch buried in the configuration screen when connected to the device via wifi. I'm curious how this meets NEC. Perhaps because the page isn't readily accessible by end users?

 

[Heliian]

Tesla's Wall Connector doesn't have a hardware switch. It is a software switch buried in the configuration screen when connected to the device via wifi. I'm curious how this meets NEC. Perhaps because the page isn't readily accessible by end users?

You can derate with software but the wiring would still have to be capable of the full power draw.

 

[Maquis]

Tesla's Wall Connector doesn't have a hardware switch. It is a software switch buried in the configuration screen when connected to the device via wifi. I'm curious how this meets NEC. Perhaps because the page isn't readily accessible by end users?

The discussion was about the wiring the Charge Station Pro on less than an 80A circuit, not a Wall Connector.

The NEC does have an allowance for derating via software as long as the software limit isn’t readily available to the end user.

 

[Nick503955]

The discussion was about the wiring the Charge Station Pro on less than an 80A circuit, not a Wall Connector.

The NEC does have an allowance for derating via software as long as the software limit isn’t readily available to the end user.

Just digging in deeper on the NEC/switch comment. Sorry for the tangent.

 

[Maquis]

Just digging in deeper on the NEC/switch comment. Sorry for the tangent.

No problem - it’s good to have this information shared.

 

[djwildstar]

Unless you have a VERY compelling reason to derate the device and the conductors, I suggest installing the full ampacity. You're introducing a potential hazard when the next owner (who does not know WTF they are doing) decides they want to charge at full rate, removes the software crutch, and burns up the wire.

When I had my Charge Station Pro installed, the electrician and I had a discussion about this. The answer is yes and no, but mostly no. Code allows you to de-rate the EV charging so that it can be safely installed at less than maximum capacity -- and it also requires protection against this type of hazard.

The Ford Charge Stations, including the Charge Station Pro, use internal switches to set the maximum power. You have to open the cover using a Torx screwdriver, and set a switch on the circuit board to change it. This isn't going to happen casually. According to code, you also have to label the device with the new current limit in a visible and durable way (so that the next owner can't say they didn't see it). My electrician was dubious about the software-only settings that Tesla and Emporia use, but apparently they're legal, too.

One of the things we discussed is installing the correct wiring for the full 100A circuit capacity needed to support 19.2kW charging, even if my panel or service didn't have that much capacity available. The idea is that the hard part (running conduit and wires) would be done and future-ready while the breaker and switch setting would be set to match why my current service and panel could support. This also has the advantage that if some future owner turns up the power level on the Charge Station Pro, the branch circuit that feeds it isn't in danger of causing a hazard.

If at some future point the panel or service was upgraded, the circuit could support 100A for EV charging without having to pull new wires. In theory, just swap the breaker and turn up the power setting on the Charge Station Pro. In practice, the likely scenario will be to replace the CSP with a sub-panel and two or three chargers in some sort of power-sharing network to divide the total 19.2kW between two or three vehicles.

 

[Maquis]

When I had my Charge Station Pro installed, the electrician and I had a discussion about this. The answer is yes and no, but mostly no. Code allows you to de-rate the EV charging so that it can be safely installed at less than maximum capacity -- and it also requires protection against this type of hazard.

The Ford Charge Stations, including the Charge Station Pro, use internal switches to set the maximum power. You have to open the cover using a Torx screwdriver, and set a switch on the circuit board to change it. This isn't going to happen casually. According to code, you also have to label the device with the new current limit in a visible and durable way (so that the next owner can't say they didn't see it). My electrician was dubious about the software-only settings that Tesla and Emporia use, but apparently they're legal, too.

One of the things we discussed is installing the correct wiring for the full 100A circuit capacity needed to support 19.2kW charging, even if my panel or service didn't have that much capacity available. The idea is that the hard part (running conduit and wires) would be done and future-ready while the breaker and switch setting would be set to match why my current service and panel could support. This also has the advantage that if some future owner turns up the power level on the Charge Station Pro, the branch circuit that feeds it isn't in danger of causing a hazard.

If at some future point the panel or service was upgraded, the circuit could support 100A for EV charging without having to pull new wires. In theory, just swap the breaker and turn up the power setting on the Charge Station Pro. In practice, the likely scenario will be to replace the CSP with a sub-panel and two or three chargers in some sort of power-sharing network to divide the total 19.2kW between two or three vehicles.

Here is the section describing acceptable means of limiting access to adjustability.

 

[djwildstar]

Here is the section describing acceptable means of limiting access to adjustability[…]

Yes, and the Charge Station Pro clearly complies with (2), since it requires a tool (Torx driver) to open the cover.

The issue with the Tesla wall connectors is if and how a password printed on the front of the Quick Start Guide isbe considered “accessible only to qualified personnel”.

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