Help with fitting dimmer switch, PLEASE!

[chicklet]

Hi everyone. I'm struggling to replace my one-way dimmer. I'm sorry but I didn't take note of the wiring of the previous switch and i've already blown one dimmer and 3 fuse wires.
The problem is that there are 3 red wires, three black and the earth wire all coming from the same hole.
Can anybody help?

 

[bongos]

Try the wiki for info on lighting circuits and this for info on dimmers.

It sounds like you have loop in wiring at the switch. Have a look round the wiki - there are plenty of guides on here.

 

[chicklet]

Thanks for the reply. what is the loop for?

 

[ericmark]

A standard ceiling rose not only supplies the lamp darning from it. But also acts as a junction box where all the lights from one floor are daisy chained together. The Loop is the line connection which goes from ceiling rose to ceiling rose and feeds each switch. But does not connect direct to lamp except where emergency lamps are used.

 

[chicklet]

Would that explain why, when I replaced the fuse wire, some of the lights in the house came on but some were still out. What do I do? Can I still fit my dimmer switch?

 

[ColJack]

yes but it will take some investigation, a multimeter, some terminal blocks and some common sense? do you have any of these things?

you need to find which red is the switch wire from the 3 you have..

with a multimeter set to continuity ( and the power off ), at the light, connect the red to the earth wire.
now test between the earths in the switch and the reds until you get 0 on the meter ( or close to it ) and / or the meter beeps at you..

this red is the switch wire.. put a mark on it with a markerpen or something so you don't loose it..

put the light back how it was before you continue.
now..

the wire you just found is the switch wire this goes in whichever is the switch wire hole on the dimmer ( might be marked as L1, or maybe OUT etc.. consult your dimmer instructions to see which )

the remaining reds go together in the live of the dimmer ( might be marked as ~, IN, LIVE, COM etc, again consult your dimmer instructions. )

the blacks are all neutrals and go together in some terminal block in the back of the box..

earths together and to anything metal ( if it's a plastic box and plastic dimmer, stick them in a terminal block like the neutrals and tuck into the back of the box. )

 

[chicklet]

I have common sense (though that's always open for debate!) and terminal blocks. What I don't have is a multimeter. I'll go out first thing and get one, then I'll go through your steps and get back to you.

Thanks for your help, it's greatly appreciated.

 

[ColJack]

see if you really had common sense you'd have made a note of the old connections or took photo's before you disconnected everything.. or asked for advise first when you found something unexpencted...

you can get one for about £12 these days.. must really get myself a new one.. kicked the last one off a scaffold and havent had to use one since then.

 

[securespark]

see if you really had common sense you'd have made a note of the old connections or took photo's before you disconnected everything.. or asked for advise first when you found something unexpencted...

you can get one for about £12 these days.. must really get myself a new one.. kicked the last one off a scaffold and havent had to use one since then.

What - your common sense???

 

[chicklet]

I don't think that's really necessary ColJack. I did realise my mistake and said as much in my first post.

 

[ColJack]

It's not a dig at you and was ment in a light hearted manner, I guess it's hard to translate a teasing tone of voice into words.. I did put the wink smiley in to show it was in jest..

it's nothing personal but we get about 5-10 people a week on here asking how to put a lightswitch / light back up or how to fit a new switch or light fitting because it's different to the old one and they never take notes or never ask before disconnecting the wires then they come crying to us asking for help and often don't supply all the info so we have to wring it out of them and ask for photo's because often their explanations are gibberish and make no sense..

 

[Steve]

I don't think that's really necessary ColJack. I did realise my mistake and said as much in my first post.

I feel it was said in good humour. Most of us dont mean to appear condescending (theres a few exceptions on here - not naming names but they should be avoided when its their time of the month).

As an aside to your original problem, if you have rewirable fuses protecting your house, then its probably time you had a full wiring inspection to verify all your wiring is up to scratch. It is unusual to find this type of lighting wiring on an old fuse board though.

 

[chicklet]

No problem ColJack. I could see your point if it was the same person coming on 5-10 times per week! This is the first time I've made this particular mistake and I'm sure it's the same with the others. I will bear your points in mind in future, I understand that the more info you have the easier it is to help. Thanks

Steve, thanks for your reply. The flat is around 30 years old. Do you think the wiring is unsafe? I'm trying to get the flat ready to sell. If I had been planning to stay I would have got the fusebox updated.

 

[Steve]

Steve, thanks for your reply. The flat is around 30 years old. Do you think the wiring is unsafe? I'm trying to get the flat ready to sell. If I had been planning to stay I would have got the fusebox updated.

buyer may demand money off purchase price to update wiring.

At the very least get the wiring inspected. i think this is nessecary for a HIP but many dont bother with these anyway.

Rewirable fuses are a very basic and primitive form of protection. An electrician will recommend a new consumer unit, which can be anything from £200 to £1000, depending where you are (London = £££££)

 

[EddieM]

you can get one for about £12 these days.. must really get myself a new one.. kicked the last one off a scaffold and havent had to use one since then.

You can get on for less than a fiver in Wickes, and it's exactly the same one that Axminster do for £20.

(Mind you I did manage to blow my laser on my mitre saw up with it, I blame it on user error though )