dimmer switch wiring

[Frederic]

Hi all,

This is my first post here and I am looking for some electrical diy help.

I would like to replace some existing light switches with dimmer switches. I could call an electrician but I feel like it should be a fairly small task that I could handle myself. We already have a dimmer switch in one of the room so I looked at it to see how it's all wired (first image below).

I then went to see what's behind the one I want to change, and the number of wires is different.
Wiring the earth should be straightforward, but what about the neutral and live? Should the neutral be wired together as per the second picture? How do I know which red wire to connect to what?

The third image shows another set up in a different room, with 3 red wires connected together. I would also like to replace that switch. Any advice? Should I just wire them the same way but on the new switch?

Sorry if it sounds like a newbie question, I never really had to deal with any electrical diy before.

Any help would be greatly appreciated.

Thanks

 

[ericmark]

Picture 1) no neutral and switch needs a load of at least 60 watt so would need changing to use LED bulbs, to work without a neutral there is always a little current flowing, most BA22d or E27 bulbs will have a by-pass within the bulb, so should work OK, but G9 bulbs may need a load capacitor adding.
Pictures 2) and 3) both seem to have neutrals, so can use a dimming switch that requires a neutral which in the main stops the problem of lights flashing or staying on dim when using an electronic switch and LED bulbs. Both are simple on/off not two way.

 

[terryplumb]

A picture of the new dimmers terminals would be useful.
However ,none of the black conductors that are connected to your existing switches are neutrals ,they are switched lives.
In pic one ( blue coloured switch) the red conductor is the permanent live ( in terminal marked wavy line)
And the black wire is the switched live.
In the last pic ( yellow switch) the red conductors bunched together in the com terminal are the permanent lives make sure you mark all of them. The other red wire is the switched live.
I can't make out the terminal identifications on the middle pic ,it may be an intermediate ,post a clearer picture please.
In a nutshell conductors that are in "com" terminals or the " wavy " line terminals would go into the same terminal markings on your new switch ( most likely new switch will have "wavy "line terminal marking)
The switched live conductor would go to L1 on new switch .
Metal switch plates must have earth conductors placed into the switch plates earth terminal.
Hope that's clear !!

 

[Frederic]

Thanks for the replies.

I haven't bought the dimmer switch yet but it is highly likely that it would be the same as the blue one on the picture above, so metal plate.
You say that the switched live would go to L1 on the new switch, but it is connected to L2 on the blue switch. Is that right?

The black switch (middle pic above) is an intermediate, with two red wires in L1 and one in L3.
In which terminals marking should they go into if the new switch has only wavy line, L1, L2.

Also just to mention that all the lights are LED.

 

[ericmark]

The blue switch shown is not suitable for LED lights. It needs a 40 watt load.

 

[terryplumb]

Permanent lives go to wavy line terminal on new switches.
So the middle switches permanent lives are the two reds ( currently in L1) .
Mark all carefully at existing switches so you don't mix them up !!
Switched lives go to new switches L1 ( irrelevant what they are in on existing switches)
Careful selection of the dimmers will be required so the wattage range they operate in will be satisfied by the load of the LEDs .

 

[Frederic]

The blue switch was already there when we moved in and it has been working fine so far although I can hear a little buzz when dimmed down and there are few occasional drops.
Thanks for the clear explanations.