wiring two gang two way light switch


Postby alex6192 » Thu Dec 18, 2008 12:15 pm

Hi guys,

I am trying to replace two light switches for dimmers.

Both switches are two way.

One of the switches has three wires and the other has two.

Each of the wires have three inner wires (excluding the bare earth) and they are coloured black, grey and brown. One of the main wires (the 3 wire box) has 'switched feed' written on it. All the other wires are unmarked.

The dimmer switch I have bought (which i intend to fit onto the box which has three wires coming from it) has two L1 terimnals, two L2 terminals and two which have a symbol that looks like a wavy line with an arrow going through it.

So, in summary I have the following.

Box 1 (excluding earth).

3 black wires
3 grey wire
3 brown wires

Box 2 (excluding earth):

2 black wire
2 grey wires
2 brown wires

Switch 1 (for box 1)

2 L1 terminals
2 L2 terminals
2 wavy line terminals

Switch 2 (for box 2)

2 L1 terminals
2 L2 terminals
2 COM terminals

Can anyone tell me how to wire these switches?

Many thanks,
Alex
alex6192
Posts: 4
Joined: Thu Dec 18, 2008 12:15 pm

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Postby ericmark » Fri Dec 19, 2008 4:34 pm

I will assume you have double two way switches at both locations?
It would not be normal to have 3 x triple and earth cables and I would guess who ever wired it bought one drum of cable and where it only required two cables just earthed the unused core. Or if not an electrician just left unused core disconnected.
So I would guess box 1 you have two unused cores and at box two one unused core.
There is no colour code all cores which are line should have brown sleeves and all that are earth should have green/yellow sleeves although in real terms it is unlikely the brown sleeves were ever fitted.
Before disconnecting you need to make careful note of which wires go to com.
Also in your case which wires go to earth, or no where.
Each cable will only connect to one switch.
Therefore in box one there will be two cables going to one switch and one to the other.
Non two way switch will have one wire to com and one to L1
The two way switch will have one wire to com and two wires to both L1 and L2 of the two wires going to L1 there will be one from each cable the same with L2.
You will have two unused wires.
With box two one cable will go to one switch using all three connections and the other will only use com and L1 connections.
In both boxes the colour going to com where all three wires are used will be the same.
The symbol that looks like a wavy line with an arrow going through it is most likely the com on the dimmer switch.
You should only use one dimmer switch on each lamp.
If you need to have one dimmer and one standard two way switch in one box you will need to use grid switches which allow you to mix and match.
If you get L1 and L2 swapped it will not matter so long as the com wire is correct.
If you have not noted the original connections the cables will need ringing out.
There is no standard but looking at my web page http://www.ericpalmer.fsnet.co.uk/Lighting.html may help you understand what you are doing. There are two main methods to wire two way switches I am assuming method 2 as shown at the bottom of my web page.
Eric
ericmark


Postby alex6192 » Fri Dec 19, 2008 5:13 pm

thanks for your reply eric, but im still not clear on how to wire them up (even after reading your website).

>> I will assume you have double two way switches at both locations?

Yes, both switches are two way doubles. The switch for box 1 is a dimmer and the other is a standard double switch.

Both 'gangs' on the switches are two-way. The first gang/switch controls 4 spot lights in the lounge and the second gang/switch controls the other 4 spot lights. So, switch 1 on box 1 controls the first 4 spot lights, switch 2 on box 2 controls the 2nd set of spot lights, switch 1 on box 2 controls the first 4 spot light and switch 2 on box 2 controls the 2nd set of spots lights.

Stuidly I remove the old switches without noting where the wires came from but one of the wires in box 1 does have switched feed written on it.

I don't really want to 'experiment' until i have a clear idea of what im doing. Using the wire numbering below could you possibly give me a dummies guide on what to do.

Box 1 (dimmer)

1. Brown (sf)
2. Grey (sf)
3. Black (sf)
4. Brown
5. Grey
6. Black
7. Brown
8. Grey
9. Black

Box 2:

10. Brown
11. Grey
12. Black
13. Brown
14. Grey
15. Black

Switch 1 Gang 1 (for box 1)

16. COM (wavy line)
17. L1
18. L2

Switch 1 Gang 2 (for box 1)

19. COM (wavy line)
20. L1
21. L2

Switch 2 Gang 1 (for box 2)

22. COM
23. L1
24. L2

Switch 2 Gang 2 (for box2)

25. COM
26. L1
27. L2

Many thanks
alex6192
Posts: 4
Joined: Thu Dec 18, 2008 12:15 pm


Postby ericmark » Fri Dec 19, 2008 8:49 pm

Simple answer is no. I would need to ring them out or be told original connections.
ericmark


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