electricallightingswitchuk
I recently put up a light in my bedroom but the switches in other rooms now turn on different lights, there are 9 wires altogether coming through the ceiling, 3 earth which are connected together, 3 red (live) which are together, 2 neutral which are together connected to the neutral on the light and a switch live which is connected with the live on to my new light. I have searched and Googled everything and nothing has worked. Please help.
Old UK wiring was as shown below
A comes from the fuse-box/consumer-unit (possibly via other junction-boxes/roses for other ceiling lights). B goes to the next ceiling light. C goes to the light switch for this lamp.
However most electricians will not have cable type C with two red wires and will have used regular cable with a black and a red wire and will put red tape around the end of the black wire to indicate it is "switched live" and not neutral (as it's black colour would suggest).
From what I've read, sometimes they would connect C's black wire to position 3 (the other red live wires) and then C's red wire would be the switched-live return from the switch. Connecting the black to the reds would make it obvious to an electrician and that might be why no wire had red-tape on it's end.
If someone has removed the red tape, you can:
A typical Non-Contact Voltage detector (NCV) and a typical mains tester
Finding which wires go to a switch using a multimeter (at least CatII 600V rated) on an isolated circuit (off at fusebox and tested for no 240V AC).
Looking at your photo, I think the top of the screw-block connections from left to right are probably:
In which case your lamp should be connected at the bottom of the two right-most positions.
It sounds like two of your red wires form a switch loop to one of your switches. The remaining red wire is the hot (I believe called active in Australia?) coming into your ceiling.
By connecting them all together, you have wired your light (and switch) directly to your unswitched power, which is why it stays on. You'll need a multimeter, voltage tester, or electrician to determine which red wire is the unswitched active.
If only one red is indeed active, then one of those two non-actives goes to a switch, and the other comes from a switch (or possibly to/from the same switch depending on how your two switches are wired).
If this whole concept sounds foreign to you, I recommend calling in some professional help (not the therapist kind).
Best Answer
Note: I'm in the US, so I apologize if I get any vocabulary wrong.
I'm going to describe the picture you posted in your question because I believe you might not know exactly what each wire is doing. I will number them left to right, 1-8 (not counting grounds/earth).
Wires 1-3: Neutrals are not switched, so they can all be tied together. Neutrals and hots should never be connected, and grounds should also be separate. Wire 1 goes to the fixture, wire 2 is coming "in" from the breaker panel and wire 3 carries on the neutral to the next box (probably another light).
Wire 4: This is the "live" wire coming in from the breaker panel. It is energizing the screw terminal block and supplying power to wire 5 and 6.
Wire 5: Gets power from wire 4 and carries it on to the next box.
Wire 6: Gets power from 4 and carries it to the switch.
Wire 7: This is colored as a neutral, but wrapped with brown tape in the diagram to show that it is doing the job of a hot wire. This is a live wire coming back from the switch. It is live when the switch is on. These two wires for the switch are known as a "switch loop" and is one of the only times (the only time?) it's acceptable for a neutral colored wire to be used as a hot.
Wire 8: Bonded to wire 7 and providing power to the lamp when the switch is on.
Now, if you confused any of the "in", "out" or "switch" wires, you could have strange results. With the hot wires disconnected from the screws and the power on, the only hot with voltage should be the IN cable. With the power off, you can check for continuity between the black and white wires of the SWITCH cable. There should be continuity with the switch on, and no connection with the switch off. The remaining cable that has no power and is not related to the switch will be the OUT cable.