John Rumm wrote:
Ben wrote:

Hmm... good question... unless the isolated garage wiring is at fault I
fear getting hold of a megger or, more likely, getting hold of a man
with a megger will be the next step! If I do manage to get hold of a
megger is it relatively straight forward using them?

Much the same as you would use a DMM on resitance range with the obvious
provisio that you are now playing with 500V and not 10V. Unplug
everything, and disconnect (or "wire out") any vulnerable electronics
that are permenently connected to the circuit that may not appreciate
the test voltage.

be aware its all too easy to unintentioanlly export dangerous voltages
to metalwork around the house with one. Meggers are something best not
used by the untrained imho. A multimeter will find the problem in
almost every case.

NT