On Mon, 6 Jul 2009 12:12:56 +0100, "Graham." wrote:


It is odd, I can only suggest they are both faulty or have been
exposed to moisture or other contaminant.
Disconnect them completely and use a multi-meter set to its
highest resistance range between L&E and N&E. If there is any
measurable leakage at all, take them back.

I'm assuming it is the RCD which is tripping. There is another
possibility which is that somewhere in the house is a neutral/earth
fault. These are commonly introduced when a new split load consumer
unit is fitted to old wiring or when a floorboard nail is put through
a cable.

The new metal faced socket may introduce a very small inductive
current, more than the plastic one will. I had a similar fault once
where simply plugging an extension lead (any extension lead, nothing
connected to it) in to a particular socket tripped the RCD. The fault
was eventually traced to a nail linking neutral and earth in an
entirely different circuit in another part of the house. The trip was
caused by the small transformer effect the extension was producing.

It was found by isolating all the neutrals in the CU and measuring
each individually for insulation to earth.