Wiring question

[Malcolm258540]

I needed to move a 2 gang switch to the other side of the doorway which I have done successfully. But I would like to understand why the wiring is as it is.

The left hand switch is the last of three that controls the hall lights – three downlights and three wall lights just above the skirting board. It isn’t the intermediate switch.

The right hand one controls the porch infra-ray security light (which is set to switch on when someone is on the doorstep or when we go out).

There are four cables inside the pattress. Cable 1 consists only of a brown which goes to L2 of the hall switch. The blue is cut and there is no earth. All the other cables are earthed to the metal pattress box. Cable 2 has a red to L1 of the hall switch and a blue that is joined to the black of cable 4 in a terminal block. The yellow of cable 2 is loose and has brown tape round its end.

The red of cable 3 goes to L1 of the hall switch, the blue to L2 and the yellow to the common.

The red of cable 4 goes to L1 of the PIR switch and the black meets the blue of cable 2 in the terminal block as described above.

A brown wire goes between L1 of the hall switch and the common of the PIR switch.

It all works – but can anyone explain what is going on?! I've attached a diagram (I think).

//www.diynot.com/network/Malcolm258540/albums/


Many thanks.

 

[EFLImpudence]

Untitled

• EFLImpudence
• 21 Feb 2013
• 1

 

[sparkwright]

Can't say for sure why it's like that, only that there's been 'some history' there. The yellow in cable 2 could have done the job of cable 1 perhaps, though with a junction box probably. Perhaps the yellow got damaged, or the wiring did something different before.

When re-wiring or doing alterations some strange though permissible things are done to save disruption.

The earth in cable 1 would have been better being connected, but there you go.

 

[ban-all-sheds]

I needed to move a 2 gang switch to the other side of the doorway which I have done successfully.

Does any concealed cabling still comply with the rules for where it can be, and is it RCD protected?


//www.diynot.com/wiki/electrics:walls

 

[Malcolm258540]

Thanks very much for the replies. Yes, that's pretty much how I figured it - though I couldn't understand why Cable 1 was there (I can tell from the chasing that it's been added later, as indeed the wire colour might suggest).

Odd, but as long as the original wiring is safe. To that end, yes, thanks, it's still in the safe zone and part of the whole home RCD.

 

[dhutch]

Could be that the yellow of C2 has failed....

 

[sparkwright]

You may be able to connect the earth of cable 1 at the light.

You say you have sucessfully moved this switch to the other side of the door. Out of interest, how did you do it?