On Thu, 30 Jun 2005 07:33:24 +0100, Mark Carver wrote:

I've got three Low Energy lamps (20 watt models). All of them audibly tick at a
rate of about 2Hz when switched off in any ceiling lamp socket in my house.

I've used a DVM (20 Meg ohms) to measure L-N, N-E, L-E voltages and there's only a
few mV indicated across any combination. Killing the lighting MCB kills the
ticking. Any ideas what's going on ?

This will be due to a small leakage current - probably the capacitance between the cores of the
cable down to the switch, especially if there is no earth in this cable (if there is an unconnected
earth core, connecting it to earth may help).
If it's a problem, it should be fixable by connecting a suitably-rated resistor across the lamp. I'd
suggest a 470Kohm 1 watt part. Do not use physically smaller parts as they will usually not be rated
for 250V operation, and could pose a fire risk.