Maria
2 x Black - 1 black will go into the Neutral terminal of your new light fitting (N). The other black is your switch live. It should be marked as a live cable and is the black that comes from the switch that you use to turn the light on and off. Its important that you find this black and mark it as a live. (Red sleeve in old money will do it)
3 x Red - These cables need to be connected together. Some fittings have blank (not connected to the fitting) terminal block for these loop cables.
2 x yellow and green - these are your earth cables and need to be connected to the earth terminal block in your new fitting, unless you have bought a double insulated fitting that won't have an earth terminal as it does not require an earth. In that case these earth cables should be connected together in a terminal block to maitain their connection and possibly pushed inside the new fitting (if you have the room)
I would suspect, based on what you have written, that the cable at the light postion that does not have an earth would be the the pair (red and black) where the black is your switch live and should be connected to the live terminl of your new light (L or L1). This cable comes from your switch.
Remeber to do all this with the fuse/mcb off for that circuit. Just switching the light off (not suggesting that you did this) will not isolate the light.
Matt, January 2009
