Gang Switch Installation Problem

[LMH2008]

hi, im having trouble installing a gang switch, which will controll the downstairs and upstairs light but to no avail, the top single switch is already installed correctly with:

Black (Common)
Blue (Common)
Red (L2)
Yellow (L2)
Red (L1)

(Thats the order what the original single switch)

now for the bit where i got confused

the old Gang Swtich which was taken out (not by me) but now left with 5 wires: 2 red, 1 yellow, 1 black and 1 blue

i just need them wiring up the correct way but i don't know which way they go

the outcome i want is: the gang switch to turn on/off one light upsairs and the other switch to turn on/off the downstairs but i also want the upstairs switch (already installed) to turn on/off

HELP!

 

[ban-all-sheds]

See the top diagram here: //www.diynot.com/wiki/electrics:lrnonharm

 

[electronicsuk]

You have 5 individual cores, but if you take a closer look you will likely find that these come in through two individually sleeved cables. One of these will have red, yellow and blue cores + unsheathed CPC (earth) and the other will have red, black and unsheathed CPC.

First assumption is that by 'gang switch', you actually mean 2 gang switch?

Second assumption is that the red and black cables from the 2 core + CPC need to go to COM and L1 on one switch, with the unsheathed CPC to the earth terminal on the switch and/or the metal backbox.

The third assumption would be that the 3 core + CPC with red, yellow and blue will go the COM, L1 and L2 on the second switch respectively, with the earth connected into the same terminals as the first cable. To be sure, you can remove the single gang switch upstairs, as it seems that the live feed and switched live return are up there, which means for your switching arrangement the L1, L2 and COM terminals simply need to be connected like-for-like between the two switches.

HOWEVER... It is NOT good practice (or a good idea) to work on assumptions, as there is no knowing how your lighting circuit has been wired without either tracing the wires back or using the proper test equipment. If you have a multimeter then we can advise on how to check the existing wiring setup.

Finally, you don't make any mention of earth/protective conductors at all. Presumably you do have earth wires at the switches, but simply omitted them from your description for clarity's sake? If you're using a metal switch (or any metal electrical fittings) then you MUST make sure they are earthed, unless specifically stated as class II double insulated by the manufacturer.

 

[LMH2008]

you don't make any mention of earth/protective conductors at all. Presumably you do have earth wires at the switches, but simply omitted them from your description for clarity's sake?

the reason why i didn't metion them because they're already there

 

[ban-all-sheds]

See the top diagram here: //www.diynot.com/wiki/electrics:lrnonharm[/size][/b]