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EV CHARGING EQUIPMENT

I am hearing from my network of contractors, that have actually read the new 722, that they have been asking charging equipment manufactures for documentary proof to comply with Note 5 of 722.411.4.

They are getting knocked back for asking or in one case a Declaration that says the particular device complies with BS 7671. I think that is wrong to declare that as BS 7671 is an installation safety standard and not a product standard. I believe that as a minimum the equipment must comply with the Low Voltage Directive and be CE marked. I also believe that manufacturers have to issue a Declaration of Conformity.

BS 7671 722 has numerous references to the various standards required such as BS EN 61851 that the equipment must comply with. I am thinking it may be illegal to offer the sale of equipment that does not comply with the Low Voltage Directive and is not CE marked?

I am hoping the countries top man of equipment safety standards, Paul Skyrme , sees this post and will come on and give us his expert view?

Has any forum member asked for a Declaration of Conformity from EV charging equipment manufacturers and received one?

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0 gkenyon over 4 years ago

davezawadi:

OK you say what if a N-E fault occurs on the cable or elsewhere in car or charger. This will trip any RCD as a large current (compared to 30mA) will be diverted to the earth conductor, bypassing the N side of the RCD. The small DC signal (lets say 12 mA or whatever) will not prevent this trip. I

DC core saturation may occur with Type AC RCDs, preventing the trip. IET Article explains.

In any case to be dangerous we need a second fault, say a lost N elsewhere and a person effectively connected to ground touching exposed conductive parts of the car.

...

The danger will be a bit more if the car has finished charging but is still connected, but under this condition we still need a fault and a person well connected to ground, whatever the RCD does.

Disagree, the N-E fault also potentially causes "blinding" of other RCDs upstream in the same circuit. It also causes circuit current to be shared down the cpc indefinitely which is not really considered "safe" in the UK - we're not allowed TN-C in the consumer installation.

Under the same conditions I can see that a large number of consumers will be exposed to exactly the same danger in many other situations.

Agreed, I personally would prefer Type AC RCDs to be scrubbed, for a number of reasons all related to the nature of present-day loads, and the increasing prevalence of embedded generation and storage systems.

It seems to me that this is getting out of proportion as it is not possible to avoid any risk without making cars class 2 which seems to be unacceptable to "the powers that be". The supposed solution is not available to be risk free, RCD or not. Because the car body cannot be isolated from the supply system (even if the supply is TT, and that is a severe problem in urban environments) we have some level of risk from faults. Such faults are very unusual (when did you last find an appliance with a N-E fault in the connecting cable?) and it is probably folk law that RCD tripping in the presence of a high fault current is prevented by 12mA of DC, although the 30mA value may be somewhat increased. It seems to me that the RCD reliability is probably less good than the cable fault scenario, and so we are not making any difference with increased complexity.

I won't repeat my other posts regarding the likelihood of moving to Class II vehicles. However, BS 7671 does have another solution in Annex 722 for separation of the vehicle from the installation, if pockets are deep enough.

"Probably folk-lore" is, I think, going a bit far, and certainly not a statement to base standards on. The issue of which RCDs are suitable for the kinds of residual fault currents that are anticipated is now well-documented in the product standards for RCDs (BS EN 62423 has been in place wince 2013). Therefore, we are now in a position that we can't "un-know" the problem with Type AC RCDs and certain types of fault current - regardless of whether it's each and every Type AC RCD, or only a few. To consider ignoring this in BS 7671 (and its international counterparts HD 60364 / IEC 60364) is really nonsensical. An argument with substantial technical evidence would be required to change this, and would probably have to start with the product standards first.
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0 gkenyon over 4 years ago

davezawadi:

OK you say what if a N-E fault occurs on the cable or elsewhere in car or charger. This will trip any RCD as a large current (compared to 30mA) will be diverted to the earth conductor, bypassing the N side of the RCD. The small DC signal (lets say 12 mA or whatever) will not prevent this trip. I

DC core saturation may occur with Type AC RCDs, preventing the trip. IET Article explains.

In any case to be dangerous we need a second fault, say a lost N elsewhere and a person effectively connected to ground touching exposed conductive parts of the car.

...

The danger will be a bit more if the car has finished charging but is still connected, but under this condition we still need a fault and a person well connected to ground, whatever the RCD does.

Disagree, the N-E fault also potentially causes "blinding" of other RCDs upstream in the same circuit. It also causes circuit current to be shared down the cpc indefinitely which is not really considered "safe" in the UK - we're not allowed TN-C in the consumer installation.

Under the same conditions I can see that a large number of consumers will be exposed to exactly the same danger in many other situations.

Agreed, I personally would prefer Type AC RCDs to be scrubbed, for a number of reasons all related to the nature of present-day loads, and the increasing prevalence of embedded generation and storage systems.

It seems to me that this is getting out of proportion as it is not possible to avoid any risk without making cars class 2 which seems to be unacceptable to "the powers that be". The supposed solution is not available to be risk free, RCD or not. Because the car body cannot be isolated from the supply system (even if the supply is TT, and that is a severe problem in urban environments) we have some level of risk from faults. Such faults are very unusual (when did you last find an appliance with a N-E fault in the connecting cable?) and it is probably folk law that RCD tripping in the presence of a high fault current is prevented by 12mA of DC, although the 30mA value may be somewhat increased. It seems to me that the RCD reliability is probably less good than the cable fault scenario, and so we are not making any difference with increased complexity.

I won't repeat my other posts regarding the likelihood of moving to Class II vehicles. However, BS 7671 does have another solution in Annex 722 for separation of the vehicle from the installation, if pockets are deep enough.

"Probably folk-lore" is, I think, going a bit far, and certainly not a statement to base standards on. The issue of which RCDs are suitable for the kinds of residual fault currents that are anticipated is now well-documented in the product standards for RCDs (BS EN 62423 has been in place wince 2013). Therefore, we are now in a position that we can't "un-know" the problem with Type AC RCDs and certain types of fault current - regardless of whether it's each and every Type AC RCD, or only a few. To consider ignoring this in BS 7671 (and its international counterparts HD 60364 / IEC 60364) is really nonsensical. An argument with substantial technical evidence would be required to change this, and would probably have to start with the product standards first.
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