Guys and Gals
Don’t forget the equipotential earth bonding ,make sure all the PE earth points are bonded with at least a 6mm csa earth conductor connected to a separate earth rod not the mains earth
Maybe not a cure but it will help
Note this should be done with all the WS equipment , including the central heating rads and pipe work
Please do not rely on the mains earth for protection
Dave knows my background and why it’s important , computer centres are one earthing nightmare