i have just taken a old style ceiling rose of and put a new modern light fitting up, wiring consists of 2 Black 2 Red and 2 Earth, i have connected to the relevant block on the light fitting, now when I turn the light off it trips my fusebox. if i turn light back on and reset the fuse it is fine light comes on but if i turn off it trips the fuse again

Dean, March 2011

When you turn the light "off" and the fuse trips - you are actually turning the switch to the ON position - the wiring fault you have made at the ceiling has live and neutral connected directly together when the switch is On - with no lamp in circuit the trip operates.

When the switch is OFF the wiring fault you have made at the ceiling has the light permanently on - until you operate the switch and trip the MCB.

The two red wires should connect together and to nothing else.

Of the two Black wires - one of them is the neutral return path and should connect to the blue wire of the lamp.

The other Black wire is Switched Live - to turn the light on and off and should connect to the Brown wire of the lamp.

Your challenge is finding out which "black" is which. Switched live often has a red or brown sleeve on it.

You will need 4 separate connections
Live - two reds - nothing else
Neutral - Black & Blue
Switched Live - Black with sleeve & Brown
Earths - all together

Take care...

Peccavi, March 2011