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John Ward has done a video,
however there seems to be some errors, having a reference electrode at a distance is not a problem, but as a TT supply you want the vehicle at same potential as the ground it is standing on, so if a metal water pipe with a broken PEN has lifted the ground to 200 volt above true earth, you also want the car to be 200 volt above true earth, so earth system needs to be local to where the car is parked.
As to earth mesh with 2Ω resistance the earth wire needs to be able to take 400/2 = 200 amp, since the supply is often only using 16 mm cable, this is clearly a problem, remember there is no fuse on the earth, so bonding a TN-C-S supply to an earth better than 20Ω is a problem due to current that can flow, where it is done commercially there is a large resistor between the DNO earth and site earth to limit the current in the earth wire.
EV charging in a garage is OK, and using three phase one can monitor the three phase voltages and auto disconnect if more than 10 volt for example, but single phase 253 - 207 = 46 volt before the unit trips, or more between phases, so can't even be sure no more than 70 volt, and unless fenced in to stop quadrupeds 25 volt can kill a cow.
It would seem a TT supply is reasonably safe, as long as all are on a TT supply, but not when some houses in a street are TT and some are TN-C-S specially if there are buried metal pipes.
Public access is different to private access, so back of my house no one should be there without my permission, front of the house however, postman, milkman and many others have good reason to walk down my drive, so any car in the drive needs to be safe to touch. I can have an isolator to remove power before I touch a car, but not visitors.
I was first aware of the problem with the guy across the road when in old house, the installation was the first I had seen, and it seemed as if a simple connection to the TN-C-S supply using a MCB, this was around 2012 when Renault Kangoo long wheel base first released, it was used for a milk round.
Next was at work, three phase supply, a pair of 22 kW charge points, told TT and RCD protected, but building is TN-C-S, and there is a metal roller shutter door very near to charge points. Not installed in house, so don't have full details. No one even thought about it to start with, but they are getting used more and more, getting to the point where two is not enough.
As EV cars are becoming more popular we have a problem is the public safe? Reading Wiring matters it states
So are the EV charging points safe, or specially with TN-C-S are they potentially dangerous, and should they get a code C2 with an EICR?
As to earth mesh with 2Ω resistance the earth wire needs to be able to take 400/2 = 200 amp, since the supply is often only using 16 mm cable, this is clearly a problem, remember there is no fuse on the earth, so bonding a TN-C-S supply to an earth better than 20Ω is a problem due to current that can flow, where it is done commercially there is a large resistor between the DNO earth and site earth to limit the current in the earth wire.
EV charging in a garage is OK, and using three phase one can monitor the three phase voltages and auto disconnect if more than 10 volt for example, but single phase 253 - 207 = 46 volt before the unit trips, or more between phases, so can't even be sure no more than 70 volt, and unless fenced in to stop quadrupeds 25 volt can kill a cow.
It would seem a TT supply is reasonably safe, as long as all are on a TT supply, but not when some houses in a street are TT and some are TN-C-S specially if there are buried metal pipes.
Public access is different to private access, so back of my house no one should be there without my permission, front of the house however, postman, milkman and many others have good reason to walk down my drive, so any car in the drive needs to be safe to touch. I can have an isolator to remove power before I touch a car, but not visitors.
I was first aware of the problem with the guy across the road when in old house, the installation was the first I had seen, and it seemed as if a simple connection to the TN-C-S supply using a MCB, this was around 2012 when Renault Kangoo long wheel base first released, it was used for a milk round.
Next was at work, three phase supply, a pair of 22 kW charge points, told TT and RCD protected, but building is TN-C-S, and there is a metal roller shutter door very near to charge points. Not installed in house, so don't have full details. No one even thought about it to start with, but they are getting used more and more, getting to the point where two is not enough.
As EV cars are becoming more popular we have a problem is the public safe? Reading Wiring matters it states
well clearly an EV charge point is the fuel filling station for an EV car, so is it permitted to have a TN-C-S supply?ESQCR prevents distributors from providing a PME earth terminal for certain installations, such as the metalwork in a caravan or boat and fuel filling stations.
So are the EV charging points safe, or specially with TN-C-S are they potentially dangerous, and should they get a code C2 with an EICR?