Wierd wires

[Jeff007]

Hi. I'm new here and after searching loads I'm happy to have found this site. Naturally I'm hoping someone can help me out.

I've just moved into a new place. In the room that is to be used as a
computer room I decided it would be nice to have a simple dimmer switch.

Well this is turning out to be a real pain. Down in the switch box I have only 2 wires a red and a black. Ground is also present but screwed to the back of the box.
Running them (r+b) thru the switch will blow the fuse. There seems to be no loop back, as i understand this only one wire (perhaps the black) would run through this switch, so how is this working? and more to the point, how do i get a dimmer working?

Thanks!

 

[RF Lighting]

As is all too common, it sounds like someone has neglected to fit a piece of red sleeving to your switch.

 

[badgerchief]

you`d only have a third wire if you had 2 switches like a landing light can be switched on 2 floors
the colour of wires is irrelevent as both red and black are live when light is on therfore a dimmer switch should be no problem to fit just make sure it is adaquate for the lights you intend to dim wattage

great diagram did you draw it yourself?

 

[RF Lighting]

There are loads in the wiki.

I did a few of them, but most were drawn by Spark123

 

[ban-all-sheds]

Running them (r+b) thru the switch will blow the fuse.

Why will it? It hasn't done before...

This shows how a lighting circuit is traditionally wired - it builds up step by step so you can see the sense in it. It also shows the 3 possibilities you'll find for colours at switches: twin red (fairly unusual), red/black with the black flagged as live (not a common as it should be) and red/black with no marking (all too common unfortunately).

[PS] Earths not shown in switch drops for clarity [/PS]


And you should probably read this post: http://www.diynot.com/forums/viewtopic.php?p=75416#75416

 

[badgerchief]

the diagrams get better and better
also note the red sleeve on the black cable in both diagrams show it is a switched live
also note you can`t dim all light bulbs !

 

[Taylortwocities]

Jeff, do we assume that you have only changed the switch for a dimmer, and not done anything else??

eg changed the light fitting.

 

[Jeff007]

Well I didnt think i reconfigured anything but now I'm not so sure. This is because I also changed the ceiling fitting. The fact is that I now realise that I've done\undone or not done something...I have somehow managed to buypass the entire switch. The are 3 blacks and 3 reds in ceiling. All bundled up on a block connector. One of the blacks seems live. The 2 other wires go to the kitchen lights. There are 2 sets of those. They go to a double and a singe switich. If i dissconect the "live black" the lights in the kitchen go out. So why is that black live?

thanks for all the great help !!

Jeff, do we assume that you have only changed the switch for a dimmer, and not done anything else??

eg changed the light fitting.

 

[Taylortwocities]

Aah, now we start to get the whole story....

You need to check that the changes you have made are in line with the diagrams above. Otherwise you will blow fuses, and dimmers.

 

[ban-all-sheds]

If i dissconect the "live black" the lights in the kitchen go out. So why is that black live?

There was absolutely no point me posting that diagram above, was there....

 

[Taylortwocities]

Nope, I rather think that its not the wires that are weird.

 

[Jeff007]

Well I would not agree with that because now I have a chance of working out what I need to do to put this right again.

Wow. I just isolated the black to the switich connceted as above and wot-d-ya-know! It bloodywell works. Yip yip!

cheers

If i dissconect the "live black" the lights in the kitchen go out. So why is that black live?

There was absolutely no point me posting that diagram above, was there....

 

[AndyPRK]

cable was made with red and black wire. When routed to a switch usually both will be lives. (in this case a red sleeve should be put on the black wire but no one bothers).

If you have been playing in the ceiling rose, and something is tripping, then I expect you have connected all the blacks together, where as the switch black (with red sleeve), should be connected to the brown lamp wire.

See diagrams

 

[Taylortwocities]

It bloodywell works. Yip yip!

Well done!