Junction box query

[Palmerston5]

Perhaps rather naively I thought I'd change a light fitting. I have to connect the new light cable into a junction box in place of the old light cable. The junction box in question has 7 cables going into it, which I have deduced from the connections are: 3 light cables (inc. the one I am trying to replace), one switch cable, and 3 circuit cables.

There are 3 sets of LV downlighters in the room below which explains the 3 light cables. And one switch, which explains the switch cable.

But what I don't understand in my ignorance is why there are 3 circuit cables.

Can anyone suggest and explanation?

Thanks.

 

[RKB]

If you look in the reference section, there are some fabulous diagrams on how loop lighting circuits are wired.
Essentially, the three reds will be loop in, loop out, and live to switch.
I have to say, it sounds a bit cluttered with all the LV feeds coming off one connector.
I think somebody here could give a supply a better way of connecting.
Hope that helps...

 

[Palmerston5]

Thanks for the reply, but I'm afraid I don't understand!

There is one cable (A) which I assume is the switch wire because it has a black wire going into a terminal where 3 red live wires are connected. Those three red wires (B, C & D) I have assumed are lighting cables. Their black wires go to what I assume is the neutral block.

Cables E, F, and G are wired into a second 'live' block which is shared with the other red wire belonging to cable A - ie. the switch.

My (albeit basic) understanding of lighting circuits is that whether loop-in or jb system, you would normally expect only 1 circuit cable going in and 1 circuit cable coming out (of either a jb or the ceiling rose).

I agree that it's all rather too cosy in this box and it would probably be better to change the arrangement but until I know why there are 3 apparetnly 'circuit' cables going in I'm at a loss as to how to proceed.

I'm sure your reply makes lots of sense but I am struggling a little nonetheless...

Sorry to be so hopeless.

 

[ban-all-sheds]

You've got 1 extra cable - everything else makes sense:

A is the switch cable.
B, C & D go off to the ELV luminaires.
E, F & G are the loop-in, loop-out and ANO - probably a 2nd loop-out.

Loop-in is easy to identify, as it'll be the only one live when everything is disconnected, and then to find out what the others do connect 1 up at a time and see what works/does not work....