Ceiling light/dimmer switch HELP PLEASE!!!

owsaboutthatthen

My mum's partner is attempting to put up a ceiling light for me. The light works no problem however doesn't switch off using the existing dimmer switch. Nothing seems to operate. Can anyone help please???

Simon_M_2

It's wired up wrong. I bet you have one red wire and one black wire going to the lamp holder. Have a look and let me know.

owsaboutthatthen

Sorry i'm on my own at the min. Do you mean the light is wired up wrong or the dimmer switch so I can tell him? The light just permanently stays on! Was working fine with the previous light fitting.

owsaboutthatthen

How should it be wired if that is the case?

Simon_M_2

First of all electricity can kill. With the greatest of respect if your mums partner can't wire it up right call an electrician. This will cost but if it stops anyone been killed then it is a small price to pay.

Most lighting systems are loop through. I assume your mums partner has had to change the ceiling rose.

A looped systems has 6 wires, three reds and three blacks. One of the red wires is permantley live so the electricity must be switched off at the main switch in the consumer unit. Never just switch off the lighting circuit as you don't know how previous owners may have tampered with the system.

The three red wires fit into the terminal labled as loop, this consists of the permanent live coming from the CU, the permanent live to the switch and the permanent live going to the next rose. You will now have three black wires left and this is where it gets tricky unless you know what you are doing.

Two of the wires are neutral loops, i.e. the neutral comes from the CU and then carries on to the next rose. These two wires are fitted into the neutral terminal in the ceiling rose along with the netural wire going to the lamp. The third black wire is the switched live from the light switch, this hould be identified by using a red sleeve but rarely is, this goes into the switched live terminal along with the live wire going to the lamp. The tricky part is finding out which black cable is the switched live. If you have access to above the fitting, in the loft for example, you can follow the three cables to find out which one goes to the light switch, if you don't have access you need a multimeter.

The above is how to correctly wire a ceiling rose, but as I say I would reccomend you get an electrician to do the job, will take no longer than 10 minutes.

Cheers Simon

ormus

the most common way of light circuit wiring.

owsaboutthatthen

Thanks for replying. My mum's partner wired up the same light fitting at my previous house using the same ceiling rose, no problems at all. However was a normal on/off switch. However just moved house, he has connected the light on the same basis but it has a dimmer switch. Does it need to be wired up differently because there is a dimmer switch? The light is staying permanently on!

ormus

no the dimmer switch should not make any difference at all.
its just a variable resistor, switch.
the black wire from the switch (when ON) becomes live, and connects to the light fitting only (brown wire).
see the above diagram.

seems like you have the brown wire connected to a permanent live wire?

Simon_M_2

Can you dim the light with the dimmer switch?

owsaboutthatthen

Simon_M wrote: »

Can you dim the light with the dimmer switch?

I can't do anything, the light just stays on bright and doesn't switch off! There isn't a fault with the switch like I say because it operated the existing light ok.

Simon_M_2

So theres your problem, the brown wire from the light has been put in the same terminal as the red wires., and so is now constantly live.