I am replacing light fixtures in the bathroom from one fixture that was part of a medicine cabinet to 2 separate fixtures. The fixtures have 3 connections – black, white and copper which I have connected. I connected the lights and they come on but do not go off when I turn the switch off. They only go off when I turn off the breaker.The switch has 3 connections – 3 black tied together, red, and 2 white tied together. The black and red wires are connected to the switch and the white wires are capped together. There is also a red wire in the box for the light that is capped. How should it be wired so the switch controls the lights?
Light switch installation
light-fixture
Related Solutions
Old UK wiring
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.
Checking
If someone has removed the red tape, you can:
- turn off the lighting circuit at the fuse-box/consumer-unit,
- check there's no voltage present with a voltage tester (preferable non-contact type) and
- separate all the wires,
- use a continuity tester to see which red & black pair are connected/disconnected by the switch
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).
Your wiring (Guesswork)
Looking at your photo, I think the top of the screw-block connections from left to right are probably:
- Live (3,4,5 in the diagram in this answer)
- Earth (9)
- Neutral (6,7)
- Switched Live (2)
In which case your lamp should be connected at the bottom of the two right-most positions.
The easy answer is "Hook it up just like the previous light was hooked up", but I'm assuming that you didn't keep track of the original configuration.
To make it work again, connect both of the lamp white wires to the white wire coming from the circuit breaker panel.
Then connect the black wire from the panel to the black wire leading to the switch.
Then connect the white wire from the switch to both black wires of the lamp.
Then, make sure you mark both ends of that white wire with black (tape, pen, paint, etc) to show that it's a switched hot so someone doesn't confuse it with a neutral some day.
Best Answer
The red is your switched-hot, so connect the black from your fixture to that
It appears that your switch was wired so that always-hot could be passed along to downstream lighting outlets while providing a switched-hot at those outlets as well, while power comes in at the switch. So, you need to turn the breaker off and move the black wire from the fixture over to connect with the red wire from the ceiling instead of the black wires. Then you can button the fixture back up, turn the breaker back on, and enjoy your new switch!