DIY Doctor


Postby vanessa10 » Fri Jan 25, 2008 6:38 pm

I have extended to cable to an existing light switch in order to move it.

In side the switch there are two gangs and four cables. 1 cable for the room it's in and 1 for an outside light. The other two are coming from the room next door. All the lights the switch for this switch are down lighters. Why bring in from next door when they have a switch of their own? and can I get rid of them?. I am having trouble getting the new switch to work. I have copied the original wiring I think. The switch was wired using all the red into the common and i way terminals. The blues into a choc box inside the switch and the earth wires in the earth point.If I remove the cables from next door
nothing works. Help.
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Postby 333rocky333 » Sat Jan 26, 2008 2:11 pm

Bit unclear what you are saying you are doing.

The lighing circuit usually will do more than room, what you do in one room can affect the next room.

If for example you disconnect the live feed in one room you would have no power at the next room.

This could happen whether you disconected at the switch or the light
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Postby vanessa10 » Sat Jan 26, 2008 3:09 pm

sorry will try to explain.

I have had to move a switch so like an idiot instead of extending the length of cables by a junction box and leave the switch alone I removed the switch and took a photo of the wiring. but can not make it work. What I need to know is is there a general rule for loop wiring i.e.the red from the lights at the end of the loop go into the commons on the two gang switch and the reds coming from the other rooms into the 1 way terminals and the blue wires into a connector or is there no rule ?
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Postby 333rocky333 » Sat Jan 26, 2008 4:44 pm

With YOUR wiring
There are a few different ways and no standard way ,
most are similar, and some methods used more commonly than others

THE PROJECTS may give you some idea or look at previous switch posts to see if anyone has similar wiring/switch to you

The blues sound correct as they are
Normally with red and blue there would be yellow either used or cut off
Not to be confused with green/yellow

If all others are red I assume ,you have wrong combination
Did you have a short peice of cable bridging across any terminals.


Two blues together

next door means back to back switches
IF you HAD a short link
Two from next door use one in each common
fit LINK between

One wire for "the room it is in"? goes to L1
One wire for outside light in otherL1
LOOK at your PICTURE and see if that was a possibility.

ONLY IF ALL ARE REDS and YOU HAD NO link , Keep the blues joined still
join 2 from other room together and other 2 also together using connectors, try all combinations of pairs untill both lights are ON, then simply put each pair across common and L1 of each switch

Sorry still not really with you on the next room bit,are they coming from a switch next room ,maybe the yellows are within that.

DO you mean
remove the cables from next door, ie in the actual room next door, WHY?
remove the cables from next door, ie coming through wall FROM nextdoor

If It is back to back switches rather than chase out walls in EACH ROOM they just come down in other room once and go through wall

You do realise this could be dangerous and would not recomend you do it if you are unsure.
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Postby ericmark » Sat Jan 26, 2008 5:23 pm

The Rules would have us use twin and earth with both wires being brown but also allow us to use sleeves instead and use the more common brown and blue coloured cores. Most electricians will use brown as feed and blue with sleeve as return but there are no rules as such to say he must do it this way. In the same way normally each ceiling rose will have live feed and feed to next lamp and then feed to switch but where it was designed for down lighting taking the feed from switch to switch is also done. There is a good set of pictures in the projects section. So yes there is a normal way but not really a rule as such.
On early houses red instead of brown and black instead of blue.

Postby kbrownie » Sat Jan 26, 2008 8:00 pm

Hi vanessa10,
Loop-in lighting circuits work like this:
You have a live, neutral and an earth, that are supplied from either another light or the consumer unit. (Depending where the circuit started) This known as the incoming supply
Then you have a live, neutral and an earth that go to the next light fitting known as out going supply (unless it is the last in the loop then they won't be one)
The next important cables are the live, neutral and earth, Switch wires. (supplying the live to your switch and then returning it to the light using the neutral cable this should have a brown sleeve on it, but they used to be tagged with red tape.
But sometimes they are red cables anyway and not black as it is not a neutral conductor. (becomes live when switched) and powers the light.

The incoming live is connected together with the out going red and red switch wire.
The incoming and out going neutrals are connected to the neutral side of the light/lamp (Blue wire in flex terminal)
The black tagged/sleeved switch wire is connected to the live side of light/lamp. (Brown wire in flex terminal)
In the switch: Live to common and Black with tag/sleeve to L1
All earths should be terminated together at light and terminated at switch.
Before harmonised colour where introduced Live=red and Neutral=Black Earth=Green, Green and Yellow
That's a standard loop-in circuit, junction boxes termination are different.
The Doctors has drawing in project section under electrical lights,swithes,wiring
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Postby vanessa10 » Sun Jan 27, 2008 3:31 pm

Thanks to everyone. Your instructions did the trick. I am up and running.
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