Mend > Lighting

RCD tripping?

I recently fit a split load consumer unit in my house. I wired the sockets to the RDC but not the lights. However, when I put the power on and flick the sockets on it is fine, but when I flick the lights on the RCD trips. Why is it doing this when they are not wired to the RCD?

Steve C
April 2008

D.I.Y, Lighting Rcd Tripping Sockets

My RCD tripped when I switched a light on. I'd crossed the neutrals! Many thanks for your help.

Patrick
November 2009

My RCD trips when there is bad weather and the mains voltage levels appear to fluctuate (lights flicker a little). It is a Marbo RCD SFOL 12 way & 10 kit system. Can the sensitivity be altered?
Colin H

colin H
January 2009

My main RCD switch is permanently tripped, but everything in the house is still working? How can this be?

Bill
October 2008

J is right on this one, the fact that you say your rcd is tripping when you turn on the light says it all
the only thing that would cause the rcd to trip is the fact that the lighting circuit neutral is being monitored i.e its connected to the rcd side

mat1e
April 2008

When you wired the consumer unit, did you keep the neutrals from the RCD protected circuits separate from the neutrals from the non RCD protected circuits? i.e. it's not just the live wires that are separated. The neutral terminal block on some consumer units may look like one block, but if you examine it closely, you will see that there is a definite insulator dividing the block in two.
An RCD works on the principle of detecting a difference in current between the live and the neutral. This difference is the leakage current and if this exceeds 30 mA, the RCD "trips" breaking the circuit. If all the circuits are connected to the same neutral block, the RCD will be comparing the neutral currents in more circuits than the live circuits connected to it.

J
April 2008

RCD's can respond to several situations - Neutrals touching earths, lives touching neutrals or earths etc - even though the ring main to that circuit may be switched completely off! I guess you have that fault on your lighting circuit somewhere. Turn all the lights off altogether, then switch one on at a time until the trip operates.

John
April 2008