Weird Light Switch - Any Ideas?

[Cinobite]

I've just bought my first house and mounted 3 down lights.
Now I'm coming to run the cables I'm a bit confused (fwiw a qualified electrician will be making the mains connection).

While I attempt to trace these cables, anyone know what's going on with this setup? The house is circa 2006.

I've replaced the single light switch with a triple (for the new lights, 2 sets of downlights plus main light)

But in the single switch, there are 2 live into the one com then a single live out on L1.
In the box, there are 3 cables. 3 live wires - wired to the switch, 3 neutral and 3 earth, N and E are terminated (see pics).

The is 1 main light in the room.
There is 1 switch for the main light.

The main light is run from a single LN pair (see pic)

The cables coming directly from the cavity of the switch contains FIVE cables (see pics) The one on over the wood goes to the main light. Then there's 2 pairs that go off (and I'm about to dig around to find where they go.

Any ideas on this? What I need to do is run 2 more cables down the wall to the switch for the new lights, but, in my very very very limited experience, there should be 1 cable, Live, Earth and Switched Live. Not 3 cables with 9 wires for 1 switch!

There is an shower ensuite with an extractor fan and a light, but there appears to be yet another cable heading over that way (although could that be for the isolator switch above the ensuite door?).

Any help would be great, does this make things easier or harder?

 

[EFLImpudence]

See: Looping at switches -
//www.diynot.com/wiki/Electrics:Lighting-Circuit-layouts

 

[Cinobite]

Thanks for the link, edited, didn't spot the next section of that page...


Ok, so this might sound stupid and please remember I won't be connecting the mains. But is there any chance that this setup means I don't have to run switch cables for the new lights?

 

[PBC_1966]

But in the single switch, there are 2 live into the one com then a single live out on L1.
In the box, there are 3 cables. 3 live wires - wired to the switch, 3 neutral and 3 earth, N and E are terminated (see pics).

The is 1 main light in the room.
There is 1 switch for the main light.

Unless there is a separate feed to some other (blanked off) lighting position, then it will be power coming into the switch on one cable, power continuing on to other parts of the house on another, and switched power to the room light on the third (the one with the single brown wire to the switch).

The cables coming directly from the cavity of the switch contains FIVE cables (see pics) The one on over the wood goes to the main light. Then there's 2 pairs that go off (and I'm about to dig around to find where they go.

Not quite sure from the photo, but are two of those larger than the others? Is there a socket or other outlet below where they disappear into the wall, either near to the light switch or on the opposite side of the wall? They're quite likely unrelated to your light switch.

 

[EFLImpudence]

You will just need a cable from the switch(es) to each light position with switched live, neutral and earth.

 

[Cinobite]

You will just need a cable from the switch(es) to each light position with switched live, neutral and earth.

On top of the 5 already in the conduit?

 

[PBC_1966]

I don't see any conduit in the pictures. If this is an interior stud partition wall (as it appears to be), the cables are most likely just dropped down the side of a stud with a few cable clips. You can enlarge the existing hole in the ceiling slightly, if necessary, or make another one alongside it and just "fish" the new cables through.

 

[sparkwright]

To clarify everything said before, you need to add two seperate cables from that switch, one cable to one set of new spots, another cable to the other set of new spots. This will allow a 3 gang switch to be fitted.

However, if getting the new cables down to the switch is going to be difficult, and it would cause damage, your electrician would be able adapt that existing wiring with the clever use of a junction box in the ceiling void/loft. By doing some clever junction box wiring, there will be no need to drag any more cables down to the switch.

Hopefully your electrician will be experienced enough to figure out how to do this. He will need a 20A 6 terminal junction box.

 

[PBC_1966]

Hopefully your electrician will be experienced enough to figure out how to do this.

If he can't figure out how to do something that simple, he has no business to be calling himself an electrician!

 

[Cinobite]

Thanks.

Just to update, so there's 3 cable pairs in the light switch box (which I know understand with looping in switches) and 5 cable pairs coming out of the top of the conduit. I can't seem to work out where the extra 2 are going without pulling the entire roof of the house apart.

When I turned off the "upstairs lights" at the consumer unit, all upstairs lights went off but the sockets remained.
I tested the 3 cables in the light switch which were all dead. But this still doesn't account for the other 2 cables.
A suggestion was made that they might be for sockets, in the bedroom (room in question) there are 3 double wall sockets.

What I'm thinking now is that if any of those five in the loft are for the sockets, then they are live while I'm trying to feed new cables down that hole. Which isn't going to be good right?
I guess what I'll do tomorrow is knock off the lights at the unit and then test all five in the loft. I guess at least that way I'll know A: They dead before I start feeding god knows what down the holes and B: They are all for lights

 

[ban-all-sheds]

What are you using to do tests?

 

[Cinobite]

I'm just testing to check the cables are dead before I put my fingers in - by putting a current detector pen in/on/around the wires inside the switch box.

 

[bernardgreen]

Testing for dead ? ( electrically )

Use a two probe tester and you will be almost dead certain it is dead ( or not dead )

Use a single probe or non contact tester and you may end up just dead.

 

[Cinobite]

Could you explain? I've seen non contact testers used a lot and come highly recommended.
I, of course, test it on a live wire before and after I test it on the unit I'm working on.

 

[bernardgreen]

A voltage can only be measured as being the potential difference between two items, Non contact voltage testers use the body of the person holding it as the 0 volt reference which is fine if the person is at 0 volts ( the ground potential ). But if person stands close to a live wire, such a the wire in the wall going to a switch then by capacitive coupling a potential is induced into the person's body. So the reference is no longer 0 volts. Hence the sensor cannot give an accurate result. It is not unknown for a person leaning aginst the wall by the switch to have a body potential high enough that the non contact tester decides the voltage difference between an earthed object and the person is high enough for it to indicate that the earthed item is live. Not a big problem. But also it will not have enough difference between the person and a live wire and will therefor NOT indicate that the live wire is live. That is dangerous and could end up in a fatal eletric shock.

The capacitive coupling passes more than enough current to deceive the tester and the person using it but far too little current for there to be any danger of electric shock to the person. Only the deceived tester with its false indication of NOT live creates the hazard.