I have a customer with a tesla EV charger, currently using a MATT E device for open pen detection.
I think it's triggering on low voltage and I have measured 216V on site without a trip whilst I was there. I live just down the road and over two hours I have seen voltage swing from 220V to 244V, don't know if we are on the same phase, he is in a different location and higher load. Voltage with EV charger off goes up by maybe 0.04V. I have another EV charger installed a few houses away a couple of months ago and was seeing 253V. we are in a village at the end of a 3 mile cable run that also has a small solar farm fairly near the start. There is a transformer in the village but I assume the ratio will be fixed.
I know there is probably something like 2v on the pen conductor, getting a slight glow on my ev tester earth test led, but Zs tested out OK. I have seen this a few times in more remote locations.
We are raising the supply voltage issue with the DNO but have a feeling they won't be able to easily fix it as it's changing so much, unless there is an actual fault somewhere.
Beginning to think about plan B, which is probably creating a TT island for the Tesla charger. Wondering what the current thinking is on how far the earth rod has to be from utilities. There is no gas and water will be a plastic pipe, do I have to worry about distance from the insulated supply cable? Anything over 5 or 6 meters will be challenging to achieve.
Then there is simultaneous contact, I assume I have to check nothing is less than 2.5m from where the car is likely to be charged. Which basically means anywhere on the drive or in the garage
I could put an Indra charger in with their PESTS system for open pen detection, but over 50% of the INdra chargers I have installed failed with burnt out connectors. They have changed their design but I would still be nervous.
