In article , says...
A mate of mine has completely rewired our house so everything in the
installation is brand new, including the split-load consumer unit. We have
an upstairs ring main, downstairs ring main and a kitchen ring main, all of
which are protected by the RCD, and the problem is the kitchen ring.

As soon as *anything* (portable radio, halogen lamp, electric drill or
whatever) is plugged into *any* socket on the kitchen ring, the RCD trips
(plugging the same things into either upstairs or downstairs rings does
*not* trip it).

Splitting the ring at the CU and using a proper Megger (500v insulation
resistance tester, not just a multimeter) to test each leg of the ring shows
the following:

L-N = almost infinity resistance (certainly over 1,000Mohms anyway)
L-E = " " " " " "
"
N-E = " " " " " "
"

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

TIA,

Mogweed




As a portable radio, which presumably is double insulated, is also
tripping it, it suggests that the fault is not on the earth, so I would
guess that there is either a neutral leg or a live leg connected to the
wrong side of the RCD.

Alternatively, if it is a Wylex S/L board, there have been quite a few
faulty RCDs coming from them of late - at least in our neck of the woods.
Doesn't explain why it is only one ring which causes the problem though.
I'd check first that the ring is terminated (both conductors, both legs)
on the correct side of the RCD first.