1 gang 1 way light switch to 3 gang 2way switch - new lights

[kbh]

Hi,

Bit of help if possible please.

I have an existing light switch currently with two sets of wires in it. There is one red from one wire going to the COM and the other red from the other wire going to L1. The neutral and earth are in are in their own separate choc blocks connecting the neutral/neutral and earth/earth from both cables.

I wanted to put in two new sets of wall lights and for these to operate separately and the existing light to operate from just the one switch (1 way). I have already purchased the two way switch as i couldn't find a 1 way in the style we already have to match the other switches.

Am I able to just piggyback the existing COM wire for the live feed into the other COM's and then run two sets of T&E to the new lights and connect these back to their respective L connections at the switch and put the neutral and earth wires into the existing choc block?

Thanks

 

[echoes]

Yes. But confirm first, using a multimeter, that the wire connected to COM is line, and the wire connected to L1 is switched line; it may have been wired the other way round.

 

[ban-all-sheds]

And also confirm that the other cores are actually neutrals, and it's not a case of the switch having been wired by a dork who didn't know you could use one cable as a switch drop.

 

[kbh]

Thanks for your responses.

I hope the guy wasn't a dork. The house was only built three years ago - i know that might not mean anything but it must count for something i would have thought?!

I don't have a multimeter - might have to invest in one. How would i check with this.

Or could it just be a case of once wired if it doesn't work just swap the COM and L1 wires around??

Thanks

 

[echoes]

If L1 is line and COM is switched, then all that will happen is your new lights will be on all the time. Never assume absence of dorks! (My mother-in-law's house was previously 'owned by an electrician' and apparently someone once got a shock off a neutral....).

I've been using one of these for over 20 years. (I do have a modern digital one as well). They don't make 'em like that any more but you can spend anything from £10 (crap) to £100 (ace).

 

[wingcoax]

If L1 is line and COM is switched, then all that will happen is your new lights will be on all the time.

In fact that would still give you switching. as both cables are connected to the switch.

 

[pjcomp]

If the house was only built three years ago and the wiring is red and black, either someone had been using up a very large supply of old-colours cable from about six years ago, or the wiring was done by the builder who happened to have some wire lying around in the back of the van - in which case the dork possibility could have increased ...

PJ

 

[ban-all-sheds]

They don't make 'em like that any more but you can spend anything from £10 (crap) to £100 (ace).

Please let me know where I can get an Avo 8 Mk 7 for £100...

 

[echoes]

In fact that would still give you switching. as both cables are connected to the switch.

How's that? One switch contact is live, the other is live depending on the switch position. If L1 was unswitched live, then there'd be no switch in series with the new lights, so they'd be on all the time. No?

 

[echoes]

Please let me know where I can get an Avo 8 Mk 7 for £100...

If only! thought that might be a bit steep for a first investment.

 

[Spark123]

They don't make 'em like that any more but you can spend anything from £10 (crap) to £100 (ace).

Please let me know where I can get an Avo 8 Mk 7 for £100...

I got my Avo 8 for free (Saved from the skip), don't know what Mk it is

 

[ban-all-sheds]

In fact that would still give you switching. as both cables are connected to the switch.

How's that? One switch contact is live, the other is live depending on the switch position. If L1 was unswitched live, then there'd be no switch in series with the new lights, so they'd be on all the time. No?

No.

You're both wrong.

He has a 1 gang switch being replaced with a 2-gang. [edit] Sorry, 3-gang [/edit]

The proposal is to link the "existing" COM to the "new" one, and supply the new lights from the new L1. [edit] Sorry, new ones, L1s [/edit]


If the existing switch is wired with the permanent live to L1 and the switched from COM then he'll end up with the 2 switches in series and the new lights will only be able to be switched on when the existing ones are on.

 

[echoes]

Yeah, you're right b-a-s! Think I had half this circuit in my head and half from that other guy with his loft light and his 'permanent switched' live.

 

[kbh]

Sorry Guys - i've been a complete Di*ck!!

Re-checked the wiring when i got home and a few things to note:

1) Wiring colouring is the new style - Brown and Blue
2) There are actually 3 wires into the switch; 2 Brown into the COM and 1 Brown into L1 - the others are still choc blocked.

 

[holmslaw]

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