In article , Mike
Harrison writes
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.
I suggested something similar the last time this came up and someone
pointed out that it would result in a fail of an electrical installation (&
insulation :-) test. If you go this route I'd put a suitably sleeved res in the
ceiling rose and stick a note to the consumer unit detailing the non-
standard installation.
--
fred