I once worked for a contractor in Stourbridge who were called to a fault in a hairdressers. I wasn't involved myself. Customers were feeling minor shocks when having their hair washed but whenever sparks turned everything seemed to be fine.
It was sussed out by the supervisor eventually. The hairdresser's was on the first floor, there was some sort of fault in the next door property which shared a fountain head with the hairdressers , only when both properties emptied their sinks and the water mixed in the fountain head did the fault transfer to the hairdressers.
Unfortunately whoever owned next door refused to do anything and wouldn't allow anyone in. All they could do was write to the local electricity supplier with details that the fault could endanger next door.
It was sussed out by the supervisor eventually. The hairdresser's was on the first floor, there was some sort of fault in the next door property which shared a fountain head with the hairdressers , only when both properties emptied their sinks and the water mixed in the fountain head did the fault transfer to the hairdressers.
Unfortunately whoever owned next door refused to do anything and wouldn't allow anyone in. All they could do was write to the local electricity supplier with details that the fault could endanger next door.