Low insulation resistance reading neutral to earth

[james hanley]

that is one way of verifying it ringer mate

 

[telectrix]

also test N/E with and without main bonding connected. surprising what plumbers can do when you let em loose with a blowlamp close to cables.

 

[andekoch]

do you have RCD's on the circuit?
try disconnecting your earth and neutral in the board to make sure you are not picking up a N-E fault on another circuit eg the immersion. also a continuity check between your disconnected E and the rest of the E's and yout N and the rest of the N's will confirm no supp bonding issues or borrowed N issues (with main switch off mind).