Landing/Hall lighting question - help!!

[Chuckles1066]

Hi,

This is my first post so I hope someone can help.

My brother has had a go at replacing the light switch in his hall and made the fatal mistake of not marking where the original wires went.

So now the hall/landing lighting doesn't work properly; can someone tell me what goes where.......this is what I found:

In the hall is a box with two switches as per the usual arrangement (one should turn the hall light on/off, the other should turn the landing light on/off). The box has six holes that accept wires, top left is COM, top right is COM, bottom left is L1 & L2, bottom right is L1 & L2.

A grey cable inside is wired thus: N to top left COM, L to top right COM, E to a securing screw against the metal backplate (although this had actually worked loose and was disconnected which would explain my brother's complaint that the lights were "doing their own thing"!!!

A second grey cable inside is wired thus: N to top left COM, L to bottom left L1.

Then there is also a single live cable that seems to loop between bottom left L1 and bottom right L2.

Any advice appreciated about what I ned to do......thanks in advance.

 

[Lectrician]

Let me source the pic again.....

 

[Lectrician]

Look at the photo in this thread. Similar prob we sorted. Ignore the bathroom switch.

Hope this will work for you.

You need to identify which is the hall cable. Best was to do this is put red and black from one cable into L1 and COM of one side of the switch, and do the same with the other. (DONT put in any other links). The switch that then turns on the hall light, has the hall cable.
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Moderator

edited to insert picture

 

[Chuckles1066]

Thanks for taking the time to reply although I've probably not explained things too well; I've had a play around with the wiring but still can't get the lights to do what they should! Sometimes both hall and landing light come on with one switch and sometimes the landing light only comes on when the landing light switch is in the on position!

I've established which cable is the hall; let me try and be a bit clearer in describing my problem, please bear with me!!

Let's start with the easiest bit - the upstairs switch has only three wires from two cables and only three places to put them - L1, L2 and COM.

COM holds the live cable from the upstairs light, L1 holds the neutral cable from the switch in the hall and L2 holds the live cable from the switch in the hall.

First question: is that all correct and how it should be?

Now onto the tricky bit - the downstairs switch; the neutral wire from the cable that links to the upstairs switch is in the top left COM, the live wire from the same cable is in the other COM and earth goes to the metal screw on the backplate.

The hall light cable's neutral wire is in the top left COM (so there are two neutral cables in there) and the live wire from that cable is in the bottom left L1.

Then, finally(!!) there is a wire in red sheathing that simply runs from bottom left L1 and connects to bottom right L2 (so there are two wires in bottom left L1).

Clear as mud eh?

Sorry if that's not very clear but is there any further guidance anyone can give me?

 

[Lectrician]

do it as the pic.

Upstairs sounds fine.

cable from up to down, red to L1 black to L2 (black is a live NOT neutral). The com must link to the other com. Hall switch and cable, red to com, black to L1

 

[Chuckles1066]

Outstanding, that worked a treat!!

Many thanks!

 

[ban-all-sheds]

Hope the lights aren't on different circuits....

 

[plugwash]

yes such systems may well indicate a borrowed neutral

however im not sure i would advise people to go ripping apart lots of their house just to correct a borrowed neutral from a light

frankly it is so common in older installs that sparkys working on a house should be aware of it and take appropriate precations

 

[andemz]

what is a borrowed neutral?

 

[plugwash]

where the neutral is taken from a different cuircuit to the live

this is fine whilst everything is connected but if one cuircuit is completely disconnected from the CU its neutral core could become live via the fitting that is connected accross cuircuits

 

[Damocles]

Surely more a case of a borrowed 'live', if anything.

 

[plugwash]

its generally refered to a borred neutral as a peice of equipment appears (from the point of view of standard sp fuses breakers etc) to be on the cuircuit supplying its live

never heared the term borrowed live used before though i can see how in some ways it could describe this situation better

 

[Damocles]

Maybe the phrase 'borrowed neutral' was invented by a PR man who thought it sounded less worrying.