New member needs help with dimmer switch fitting!

[Marko62]

I have recently fitted low voltage downlighters(4x 20 w halogens) in my bathroom but want to be able to dim the lighting. The electronic transformer is dimmable and I have bought a 2 gang 2 way Varilight low voltage dimmer.The dimmer is suitable both for mains and low voltage lighting. The socket outside of the bathroom is on the landing and has 2 switches on it: one operates the bathroom lights the other is on a two way-circuit and operates the stair lights ( a pendant with 3 x 60 watt bulbs)
I removed the old switch and copied the wiring configuration for the dimmer. The configuration was as follows: red to L1, black to L2 and red to Common for one module of the dimmer(the 2 way circuit) and red to common, black to L2 for the other module(one way circuit). I made sure that the red to Com in the switch went to the Com in the dimmer.
I switched on the power and both circuits were dead so I then bridged the 2 coms on the dimmer as suggested in the instructions. However, this resulted in the landing lights being on permanently, though the halogen lights in the bathroom operated fine. I have no idea what to try next! Any help would be appreciated-- I am certainly an amateur but would hope the job is not something I should not have attempted. I am keen to learn!

 

[Steve]

disconnect the 2 coms - if they werent like that to start with, and your 2-way switching would be messed up with that.

The other end of the 2-way circuit, isn't a dimmer is it? Just a normal switch?

Do you own a multimeter? Could you find a permenant live?

Replacing a switch is well within the realms of DIY electrical work, but sometimes things go wrong, even when you have done it exactly right, as here!

confused about why the bathroom lights worked with the link wire. Are either of the wires you connected (COMs) permenant lives? AFAICT, your bathroom light should work fine without the link wire. The wire in COM for the bathroom light is perm live. The other COM, it would appear, is switched live to the landing light.

 

[Marko62]

Thanks for the swift ,considerate supply crafty! The other switch on the 2 way circuit is indeed an ordinary switch as I realise that only one switch on a two way circuit can be changed. Sorry I don't have a multimeter. Why I bridged the 2 coms on the dimmer was because when the dimmer did not work after copying original configuration I put the original switch back on but connected up only the one way circuit to the bathroom, leaving the wires for the 2 way circuit unconnected. I thought this would operate the bathroom lights but they did not come on. This suggested to me that the 2 way circuit terminals and the one wayterminals were perhaps internally bridged as there was no visible bridging wire on the original switch. Would that mean that the live feed , whichever wire that,is feeds both circuits? Sorry if none of this makes sense, I'm just trying to use logic as I have no knowledge of electrics. Thanks.

 

[breezer]

here's a very very vague thought

suppose one switch is old and the other not, it maybe (but unlikely) one is upside down.

put both switches down and compare markings are they in the same place?

 

[Marko62]

Thanks breezer. Not quite sure what you are getting at here! What do you mean by 'compare markings?' Do you mean that when I put the original fitting back on connecting up only the one way circuit that bathroom lights did not come on because the switch was off and should have been on? Is it possible to tell when the fitting is upside down other than by the position of the switch? Please enlighten-- much appreciated!

 

[Steve]

i think breezer means that some switches are arranged so the 2 switches are opposing each other, so the terminals at the top read L1 L2 COM and the terminals at the bottom read COM L1 L2, and this often causes confusion amongst DIYers who assume the top row is for one switch and the bottom row is for the other switch, when in fact, the terminals are arranged in triangles.

Dimmers, though, thankfully are usually divided into 2 modules which makes identification easier!!

 

[breezer]

i think breezer means that some switches are arranged so the 2 switches are opposing each other, so the terminals at the top read L1 L2 COM and the terminals at the bottom read COM L1 L2,

yep

 

[Marko62]

I see now!! 2 modules in the dimmer switch but one is opposite way round from the other and terminals clearly marked L1, L2, C. Crafty, if the wire in Com for bathroom light is perm live then as you suggested the bathroom lights should have worked.. Do I need a meter to test this? If so I will get one tomorrow. Any more suggestions as yet, guys! I appreciate your help so far.

 

[Marko62]

So the top row of terminals are not for one switch and the bottom row for the other? I assumed that this was the case and so when I wired up the dimmer ,I connected the wires from the top row of the original fitting into the corresponding terminals according to the L1 L2 Com markings of the dimmer module. Not sure what crafty means by the terminals being arranged in triangles.

 

[breezer]

. Not sure what crafty means by the terminals being arranged in triangles.

draw a triangle, put c at the top, L1 bottom left, L2 bottom right = triangle.

now do the same again, cut it out turn it upside down and place it next to first one= 2 triangles.

sorry i cant draw it in this forum

 

[Adam_151]

 

[breezer]

"voice over"

Adam151 arrives in the nick of time to save the day with a drawing

 

[Jodo]

[/img]

 

[Jodo]

sorry Adam_151, didn't refresh before I posted.

 

[Steve]

Marko, can you take a picture of the back of the switch?