Help required with wiring 2gang-2way varilight master and slave dimmers

[matt96]

Hi

Be gentle with me- its my first post!

We have a top and bottom of stairs set up. At both top and bottom there are 2 gang 2 way switches. At either location, one switch operates a single light at the bottom of the stairs, and the other switch operates two lights together at the top of the stairs.

Somewhat confusingly, the lefthand switch at the top of the stairs operates the lights at the top of the stairs, and the right hand switch the light at the bottom. By contrast, the left and right switches at the bottom of the stairs operate the other way around.

Having read thoroughly here I identified the Varilight IQ touch 2 gang 2 way master and slave dimmers. Easy, or so I thought!

I'm a bit stuck as to how to wire up the dimmers so I've made a schematic of the back of the two existing switches (attached). On the existing switches, the two switches are side by side, but rather than two columns of terminals there are two rows, marked COM, L1 and L2.

Here are the things that are confusing me:

1) Which switch (upper or lower) should operate as master and which as slave?

2) What is the conversion between COM, L1 L2,(old switches) and Live, S and ~/^ on the varilights?

Help gladly appreciated!

Many thanks, Matt

[kevcfc]

By upper and lower do you mean top and bottom of stairs m8?

The first switch in the circuit should have a link between both 'com' terminals.

I've not come across the 'new' labels, even the two I've just fitted today are marked up using com, L1 and L2. I would imagine that 'Live' would be 'com' and the other two L1 & L2, it doesn't matter which way you get L1 & L2 just as long as you get the 'Live' right.

Dunno if that helps at all m8

[matt96]

Hi Kev

Thanks for the reply. Yeah by upper I mean the one at the top of the stairs, and lower = bottom. I don't know whether I should install the master 2g2w switch at the top of the stairs (upper) or bottom of stairs (lower).

With a bit more searching on the varilight I now know which terminal is 'load' 'slave' and 'live' too. Its getting which is the live wire right I am worried about principally- that should be the one marked 'com' in old money, yes?

[kevcfc]

Yeah Matt, thats the one m8. The other two are you're strappers.

I've never used these 'varilight' switches so I'm not sure how they differ from a normal 2w2g switch. If one of you're old switches has a short piece of wire between the two 'com' terminals then that will be the first switch on the circuit, which to me would make it the master switch

HTH

[matt96]

Originally Posted by kevcfc

Yeah Matt, thats the one m8. The other two are you're strappers.

I've never used these 'varilight' switches so I'm not sure how they differ from a normal 2w2g switch. If one of you're old switches has a short piece of wire between the two 'com' terminals then that will be the first switch on the circuit, which to me would make it the master switch

HTH

Hi Kev- I have really cr*ppy pics of the back of each of the existing switches but there are no simple wire loops between the com terminals.

Does it matter which is master and which is slave ?

[kevcfc]

Hmmm, I don't know TBH, I think it's gonna be a case of suck it and see.

I've just looked on the Varilight website and all it says is that you can only fit one dimmer on a two way lighting circuit, the other has to be a standard two way switch.

I couldn't find any reference to master and slave dimmer switches, not much use really

EDIT: Right, found a wee bit of info. It seems that the master does go at the first switch, with the slave (or slaves) replacing every other switch in the circuit. The only problem for you now is to work out which switch has the feed into it and which one has the load going out of it to the light(s).

[matt96]

Originally Posted by kevcfc

EDIT: Right, found a wee bit of info. It seems that the master does go at the first switch, with the slave (or slaves) replacing every other switch in the circuit. The only problem for you now is to work out which switch has the feed into it and which one has the load going out of it to the light(s).

Thanks Kev.

Is it a question of going up in the loft to find this out or getting busy with a multimeter? I have no idea which switch is first or last.

[kevcfc]

Hi Matt,

I would use the multimeter m8.

Isolate lighting circuit, put live wire in ceiling rose/light fitting down to earth, disconnect wire out of switch com terminal, test between that and earth. If you get nothing then try the other switch, one of them should give you a reading and that will be you're slave switch.

Sorry if I'm teaching my Grandma to suck eggs

[matt96]

Originally Posted by kevcfc

Hi Matt,

I would use the multimeter m8.

Isolate lighting circuit, put live wire in ceiling rose/light fitting down to earth, disconnect wire out of switch com terminal, test between that and earth. If you get nothing then try the other switch, one of them should give you a reading and that will be you're slave switch.

Sorry if I'm teaching my Grandma to suck eggs

Hi Kev

Not at all. I do a bit of electronics stuff at work but have never tried to apply it in domestic AC- am a bit nervous putting the theory into practice!

I'll let you know how I go.

[kevcfc]

OK mate, good luck