How can I change a ceiling light. I have three cables, all with earth, neutral and live. I have identified the switch live and wired it on its own to the live wire. The other live wires have been kept together. But still the light wont work!
you'll have a L,N & E coming in, a L,N & E going out to the next fitting. One of the cables will be used to send a L to the switch, and return it to the lamp. The lamp then will be wired to N and the return switched L. For safety's sake, the black conductor of the switched live is usually tagged with a bit of red tape.
It sounds like you've picked up a L, sent it down to the switch, and returned it to the N. Any blown fuses at this point??