Wall lights causing RCCB Trip

[discjockey1999]

Hi there, have recently wired up some wall lights and am having problem

with them tripping the main RCCB on the CU.

Decided to wire up the lights from a fused spur on ring main, which have done in the past and has been fine. The two lights are 'dais chained' from one to the other.

When i tried switching on one light (from one-way 1 gang wall switch it was fine, but with two it trips the RCCB every time. The ring mai is on RCCB side of a split load CU. The current RCCB is 63A-30mA.

Does anybody know why this is happening? Is it ok to wire it up i this manner? Is it possible to change the RCCB to prevent thi happening, or would i be better off altering the wiring for the lights

Please help

-- discjockey1999

[Chip]

On Tue, 21 Jun 2005 18:15:12 +0100,it is alleged that discjockey1999 spake thusly in uk.d-i-y:

It's highly unlikely the RCD is faulty, if it's the same light each and every time, I would bet on you having either a live-earth fault in the second light, or a miswire swapping neutral and earth.

From your description, it sounds like the second light [last in the chain] is the one with a fault. Don't change/bypass the RCD even to test it, please. [changing it would cost you money, bypassing might cost you the house or your life]. RCDs are not *that* sensitive that a light should leak enough to cause a trip.

If you have access to a multimeter, disconnect the second light from the first, and check the cable to the second with no bulb in there, you should read infinite resistance from any wire to any other wire with a normal battery powered meter. Then put a bulb in, and check again, making sure your low reading is between live and neutral, with again, infinite resistance from the earth to any other wire.

Possibilities other than miswires could include loose strands of wire, possibly caused during manufacture, fixing screws puncturing the cable, etc.

*standard disclaimer: And to risk stating the obvious, if in doubt call an electrician :-)

HTH

[John Rumm]

Could also be a earth neutral short...

Screws through cables seems to be a favourite with wall lights.