Using a junction box

[Gavin0268]

Hi
I've got an existing 2-way switch, in amongst a mess of wiring in the attic. There's currently 4 lights and a ceiling fan coming out of one monster junction box, all feeding off one supply cable. I'm trying to sort them out into separate junction boxes.
My question is - the only cables coming from each switch is 3-core & earth, with all the connections being made at the junction box - is that safe (it obviously works!), or would you suggest dropping cables down to the switches and following the 'correct' method (not easy, but am decorating anyway, so not too much of an upset.

 

[mapj1]

Its not electrically wrong the way you describe- the use of three core allows for 2 way switching to be added if ever needed, at the moment I presume live goes down and switched live comes back - though really the switched live should be marked in a little bit of red sleeve at the ends, to avoid people thinking its neutral, but the extra core is harmless, so long as its kept out of the way - a loop and a cable tie is fine, or make it an extra earth!

However one big overflowing JB is not so hot, and splitting it into a number of 4 or 6 terminal ones would be better - get the bigger ("heavy duty") ones with some room inside if you dont like fiddling - they are far easier to work. probably worth some labels or some photos for the album too, so you can remember what is what. Look at the 'for reference' pics on this forum for what you should end up with.

 

[Gavin0268]

The circuit is already switched, I was just confused as most of the wiring diagrams for 2-way switching have the cabling connections at the switches, rather than at junction boxes. The only one I've seen is at www.diydata.com/planning/twowaylight/twowaylght.htm - but that doesn;t have the power cable going off to the next junction box - I assume for clarity, and it will just come out the other side of the same terminals.

All the cables have the right colour (hopefully) tape on them.

Spent about 2 hours tracking cables all round the loft at the weekend trying to figure out what went where from the big lump in the box. In the end it all made sense!

 

[AS]

I have been crawling around trying to make sense of the same stuffed junction box lighting circuit situation . I can't find any info to read on what is happening in this type of system as it doesn't seem to be like a conventional junction box system or a loop in system.

We have a room with 2 wall lights on left and 2 on right they are operated by one 2 gang switch (1 lights up 2 on left and 1 lights up 2 on right) there is only 1 cable going to this switch and everything feeds into a large junction box PACKED with wires. can anyone explain what is happening here - I want to make a plan for our electrician for creating new lights and altering what switches what on from where and am trying to get a bacis understaning of what is exisiting first!

 

[Lectrician]

Nothing wrong with a 3 core to each 2 way switch from a central point. There is nothing set in stone on how to wire lighting circuits, there are many weird and wonderful methods out there as 'short cuts' and 'cable savers'.

Why do you want to tidy JB's in a loft??

One sounds fine for what it is switching!

 

[securespark]

Yes, the NIC recommend all unused cores be tagged to earth.

 

[Gavin0268]

Why tidy up junction box in the loft? I used the term 'junction box' a bit loosely, its actually just a bakelite box which contains all (about 7) different collections of cables, twisted together and taped over. They all go to different lamps, fans, switches etc but all come off the one supply cable (ie 6 red wires, 6 black wires, 6 earths all twisted together, plus others). There's plenty bare bits of wire showing, and the box doesn't close properly as it's so full. Even the one section of ring main which is in it's own junction box has a broken lid, so keeps getting knocked off. Add in the odd mouse/rat roaming around....