Hi Thanks again for the help.
Yes, cable changed for new one and also run off a nearby but on separate MCB ring main and same problem.
Insulation and resistance of the new heater seems OK, but only measured with a standard type multi meter.
Next step is to try disconnecting some neutrals as well as switching off the MCB to the other circuits to see what occurs. Well let you know!
Cheers Pete
Yes, cable changed for new one and also run off a nearby but on separate MCB ring main and same problem.
Insulation and resistance of the new heater seems OK, but only measured with a standard type multi meter.
Next step is to try disconnecting some neutrals as well as switching off the MCB to the other circuits to see what occurs. Well let you know!
Cheers Pete