EVSE and GFCI PROTECTION

[jim dungar]

(The EVSE is off until the handshake with the car is complete, then performs a variety of checks including for ground continuity, then flips a relay to connect the car to the premisis wiring. The GFCI false trips are vehicle dependent and condition dependent). The protections from an EVSE have the same goal as a NEC GFCI.

As you stated, any possible GF protection provided by an ESVE doesn't occur until handshaking with a car has been completed.

NEC required GFCI protection is provided whenever the branch circuit is energized.

 

[jaggedben]

As you stated, any possible GF protection provided by an ESVE doesn't occur until handshaking with a car has been completed.

NEC required GFCI protection is provided whenever the branch circuit is energized.

'Possible' is incorrect. While it may or may not be that with current designs protection isn't provided on the line side of the contactor inside the EVSE, there's no reason it couldn't be.

Aside from that, a hardwired EVSE really no more needs to provide protection when a car isn't plugged in than a receptacle does when nothing is plugged into it.

 

[jim dungar]

Aside from that, a hardwired EVSE really no more needs to provide protection when a car isn't plugged in than a receptacle does when nothing is plugged into it.

If the vehicle is not present isn't there still a charging cord that could be touched? I am pretty sure the EVSE is not being removed from the branch circuit.
How about when the hand shaking doesn't work correctly or the EVSE is defective.
The EVSE RCD is still missing the 6mA threshold for Class A personnel GFCIs.

 

[wwhitney]

If the vehicle is not present isn't there still a charging cord that could be touched?

Sure, but there's a relay in the EVSE that ensures the cord isn't energized until the handshake is complete.

The first order safety difference between an EVSE and a GFCI is that the EVSE uses CCID20 with a 20ma current imbalance threshold, while the GFCI uses a 4-6 ma current imbalance threshold. There may be second order differences I'm not aware of, such as whatever measures a GFCI uses to minimize the chance of the relay failing closed and being unable to disconnect when excess current imbalance is detected, vs whatever measures an EVSE takes in that regard.

The EVSE standard includes an option for CCID5 with a 5ma current imbalance threshold, which would be equivalent to a GFCI to first order (assuming that the trip time requirements are the same, but IIRC they are). However I'm not aware of any products to that standard that are commercially available.

Cheers, Wayne

 

[jaggedben]

If the vehicle is not present isn't there still a charging cord that could be touched?

Yes. So? As stated above, the cord won't be energized under normal circumstances until the car is plugged in. But even if it were, if a hardwired EVSE provided protection to the entire cord how is that different from a receptacle providing protection at its blades?

I am pretty sure the EVSE is not being removed from the branch circuit.
How about when the hand shaking doesn't work correctly or the EVSE is defective.

Any real world instances of that? How about when a GFCI breaker or receptacle is defective? How is this relevant? How would the answer show that receptacles and level II hardwired EVSEs should be treated differently?

The EVSE RCD is still missing the 6mA threshold for Class A personnel GFCIs.

As things stand, that's true AFAIK. But your 'possible' statement seemed to preclude that it is possible for an EVSE to meet that standard, which only time will tell. My opinion is that if a hardwired EVSE *did* contain functionality that met the standard, it should be allowed by code to provide it. (In fact my opinion is that something like CCID20 should probably be allowed, but that's further into the weeds than the point here.) But the code as currently written is at best hard for most professionals to understand, and at worst discriminatory on this.

 

[jim dungar]

How would the answer show that receptacles and level II hardwired EVSEs should be treated differently?

I don't think they should be treated any differently. To me, the EVSE is the outlet and as such it must be protected based on the wording in the NEC.
Yes, new products may exist someday. Yes, Class A GFCI operating parameters may not be needed. But what is written is all we can deal with today.

 

[jaggedben]

I don't think they should be treated any differently. To me, the EVSE is the outlet and as such it must be protected based on the wording in the NEC.
...

So a GFCI receptacle must also be protected? By a breaker?

 

[jim dungar]

So a GFCI receptacle must also be protected? By a breaker?

By Listing requirements, the electronics and mechanism of a Class A GFCI protect the outlet portion of the receptacle assembly.

I am working with the existing NEC words, whether I think they should or should not be changed.

 

[jaggedben]

[

I don't think they should be treated any differently. To me, the EVSE is the outlet ...

These statements are contradictory.

By Listing requirements, the electronics and mechanism of a Class A GFCI protect the outlet portion of the receptacle assembly.
...

And an EVSE is the same ... unless you think they should be treated differently.

 

[brycenesbitt]

Oh my such disagreement. Clearly there are polar opinions, but that's not how code is (supposed) to be made.

Can we get back to safety for the moment?
EVSE have been installed without an upstream GFCI for a long time, we have probably millions of units
operational today in all climates and weather.
The code can indeed be amended, and before it goes into effect in some states even.

* Has a proponent or code process reviewed any case history of an injury or incident with EVSE?
* What mechanisms of harm are there, addressed by the upstream GFCI?
* Why did IEC choose the 20mA threshold for the EVSE ground fault protection and view it as adequate globally?
* What's the cost of adding the GFCI compared to the benefit?

* What other solutions are there? For example I would strongly support a requirement that the EVSE cord attachment point be segregated within the casework and have a breakaway feature so nothing bad is exposed in the case of cord yanking incident.

 

[don_resqcapt19]

Oh my such disagreement. Clearly there are polar opinions, but that's not how code is (supposed) to be made.

Can we get back to safety for the moment?
EVSE have been installed without an upstream GFCI for a long time, we have probably millions of units
operational today in all climates and weather.
The code can indeed be amended, and before it goes into effect in some states even.

* Has a proponent or code process reviewed any case history of an injury or incident with EVSE?
* What mechanisms of harm are there, addressed by the upstream GFCI?
* Why did IEC choose the 20mA threshold for the EVSE ground fault protection and view it as adequate globally?
* What's the cost of adding the GFCI compared to the benefit?

* What other solutions are there? For example I would strongly support a requirement that the EVSE cord attachment point be segregated within the casework and have a breakaway feature so nothing bad is exposed in the case of cord yanking incident.

That is consistent with the IEC philosophy of ground fault protection for people that is substantially different from ours.

Theirs is to trip at a point at threshold of ventricular fibrillation, while ours trips at the threshold of let go current. There is also a significant time to trip difference between the IEC devices and a UL 943 device. The IEC devices have a maximum trip time a their rated trip point of 300ms. Assuming a 20 mA fault, the permitted trip time for a UL 943 device is 1 second.

I fail to see a need for ground fault protection for hard wired equipment, but given the cord connection between the EVSE and the vehicle, there may be a need for ground fault protection within the EVSE.

 

[brycenesbitt]

I fail to see a need for ground fault protection for hard wired equipment, but given the cord connection between the EVSE and the vehicle, there may be a need for ground fault protection within the EVSE.

Doing whatever it is within the EVSE is better. The EVSE can notifiy the vehicle driver in many cases, call for service, etc.... in a way an upstream GFCI has no chance of doing. Note we will soon be on J3400 for home chargers, not J1772, and some details differ. 277V charging is also on the way.

 

[don_resqcapt19]

Doing whatever it is within the EVSE is better. The EVSE can notifiy the vehicle driver in many cases, call for service, etc.... in a way an upstream GFCI has no chance of doing. Note we will soon be on J3400 for home chargers, not J1772, and some details differ. 277V charging is also on the way.

I don't see a good reason to permit the ground fault protective device to be in the EVSE where the EVSE is cord and plug connected.

 

[jaggedben]

I don't see a good reason to permit the ground fault protective device to be in the EVSE where the EVSE is cord and plug connected.

He was talking about the cord connection between the EVSE and the vehicle. Why shouldn't a hardwired EVSE be permitted to provide that (if it meets the standard you want)?

 

[don_resqcapt19]

He was talking about the cord connection between the EVSE and the vehicle. Why shouldn't a hardwired EVSE be permitted to provide that (if it meets the standard you want)?

I already said that it could, but right now none of them provide protection equal to a UL 943 Class A GFCI device.

 

[brycenesbitt]

I already said that it could, but right now none of them provide protection equal to a UL 943 Class A GFCI device.

The false trip issue is that the vehicles themselves vary, and involve a lot of high frequency AC to DC and DC-DC switching gear.
Over a 40 amp charging session, glitches of 5mA can happen. But that said at least if the EVSE did the shutoff, it would know and
could both retry (as EVSE do) and notify (as EVSE do) rather than a dump old school GFCI that can just turn off and thumb it's nose at the owner who wanted to get to work the next day.
EVSE also meet vampire energy codes that NEC style GFCI are not subject to.

 

[Rjryan]

Just received a EV Charging White Paper: Powering the future of global transportation, electric vehicle charging by Joe Pablo and Ken Boyce
Attaching page 8 of the white paper.

 

[brycenesbitt]

And again: is there any evidence of an actual problem? Any incidents worldwide? Any close calls?

 

[retirede]

Just received a EV Charging White Paper: Powering the future of global transportation, electric vehicle charging by Joe Pablo and Ken Boyce
Attaching page 8 of the white paper.

Looks like a picture of an email.

 

[don_resqcapt19]

Just received a EV Charging White Paper: Powering the future of global transportation, electric vehicle charging by Joe Pablo and Ken Boyce
Attaching page 8 of the white paper.

Nothing that we can read there, but it doesn't matter what they have to say, unless what they say makes it into the NEC.