I recall a friend who was a radio ham fitting an earth pit in his garden, this was for the transmitter, 4 earth rods one each corner of garden and earth tape buried 1 foot deep connecting them, never measured the earth as could not get far enough away to put in test probes, but it was clearly very good.
The earth was connected to a copper earth bar in his shed (shack) and the transceivers were connected to that, and he got a local electrician to wire up his shed, for some reason the 4 mm earth wire from the house was tie rapped under the feed cable, any way I got a call on 2 meter radio, he said my earth wire is getting hot, I said turn off your power, he replied he had done that, no change, so I drove down.
On arriving the earth wire was a load of copper balls under where it had been, and measuring voltage it was swinging between zero and 400 volt so rang the DNO and said think you have lost your earth/neutral they replied impossible that can't happen, but soon after there was an electric van at some road works down the road, and my friend was only house that did not have loads of burn out equipment.
Until that point I liked PME, but then realised under fault conditions there is a problem, it does not happen very often, but since then I have seen where copper theft has caused fires where the gas pipes have tried to earth a premises, now there are isolators in the gas pipes so pipe in ground and pipe in house not connected, and where every house has gas and water bonded, any fault load is shared, his problem was all houses in street were using his 4 mm earth wire.
However it is clear you can't really have earth electrodes and PME earth bonded together, at least not a good earth electrode, 60 ohm would be OK, but would guess his earth was better than 1 ohm.
Not got my copy of BS7671 here with me, but seem to remember diagrams showing arms length and instructions on how to earth cow sheds, OK dogs should not roam loose, and cats are quite small, however Colwyn Bay at the moment has wild goats roaming around the town, due to so few people on the streets, and are causing damage eating anything in sight, so we do get wild animals in our towns.
So any earthed metal structure must have enough distance from any other earthed structure using a different earth. So 25 volt is enough to kill a cow, and a cows legs are around a meter apart, so 230 volt divided by 25 = approx 9 meters, that is how much space is required to get a gradient shallow enough not to kill a cow, so 5 meters is a bit close, however electrically I think you may be correct 2.8 meters does seem to ring a bell, and I think fire regulations allow 3.5 meters at corners, only 5 meters side to side, 6 meters if not metal skin on caravan, so if cars parked in herring bone patten then 3.5 meters corner of car to building.
I am sure where I work the electric roller shutter doors are earthed, and the charging point is not 2.8 meters from the doors, and cars on charge could be right next to the doors, there is a lead from charging point to car, and the car is maybe 14 foot long, so unless the charging bay is clearly marked out with curbs etc to stop cars parking too close, then even if the charging point is 2.8 meters from any metal work earthed to buildings earth system, it does not mean the car will be that far away.
I would assume this would all be included in the training? We are not only trained to follow regulations we are also trained in how electric works, and to any tradesman it should be clear what distance is required, but where the problem lies is how do you say know if the regulations allow it. Same with this virus and building firms, if the government says stop, OK, but unless government says stop, any over time fines remain, same with regulations, if my boss says go and fit a charging point and it can't be done within regulations, simple I return saying can't be done, but however dangerous, how do you refuse to fit it, if it complies?
And at the end of the day, the fault which allows PME to end up with bonding to line, is rare, even with TN-C-S to the charging point one would be very unlucky for a fault to make it live, but it can happen, so petrol stations, boats, caravans, and like can't use PME.
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