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Replacing switch with a dimmer in a 3 way installation

Discussion in 'Electrics UK' started by Greggerly, 20 Sep 2021.

  1. Greggerly

    Greggerly

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    Hi guys.

    Trying to instal a dimmer switch but the arrangement I have is quite tricky so though I will ask for some advice.
    So the lights in my house can be controlled via multiple switches.
    I have 2gang 3-way switch in the kitchen to control kitchen and living room lights.

    I have 2x 1gang 3-way switches in the living room - one controls the living room light and one controls lights on the stairs.

    and there is another 2gang 3-way switch on the stairs to control lights in the living room and on the stairs.
    I know that I can't have more than 1 dimmer in the setup or it will flicker.
    Since the living room dimmer is most crucial I would like to replace one of the 1gang 3-way switches in the living room.
    - Can I also replace another 1gang 3-way switch in the living room (the one which controls the stairs light) or will it flicker?
    - The 1gang 3-way switch in the living room have 2x L1 and 2x L2 connectors while the dimmer has only a single L1 and single L2 plus ground. How should I wire it?
    - Anything else I should be aware of?

    thanks for all the help
     
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  3. RandomGrinch

    RandomGrinch

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    Hi,
    Personally I would avoid touching the switches and use something like a remote controlled dimmer module, connected directly to the light:
    https://www.amazon.co.uk/MoesGo-Dimmer-Universal-Compatible-Control/dp/B087T9B213/
    Or:
    https://www.amazon.co.uk/Sonoff-D1/dp/B082V7QR19
    Others are available with a physical rf remote control.
    It definitely makes connecting simpler! :)
    (Although having the module at least semi-accesible might be necessary for pairing issues etc.)
    EDIT:
    Or simpler still, depending on your light fitting, get a smart bulb!
     
    Last edited: 20 Sep 2021
  4. 333rocky333

    333rocky333

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    Sounds like a 1 way dimmer and not suitable


    Sounds like an intermediate switch
     
  5. ericmark

    ericmark

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    Today you need to follow manufacturers instructions. Years ago we used two x two way switches and intermediate switches, but today we have master/slaves, other a "S" terminal links master to slaves. This means any switch can be used to adjust light level. Often the "S" terminal is extra low voltage, so you can't mix and match.
     
  6. winston1

    winston1

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    There are no three way switches. They are mostly two way switches except the living room one which is an intermediate switch. You can get two way dimmers but with those you can only dim from one position. Don’t think you can get intermediate dimmers though.
    As Eric says you can get master slave dimmers. To use those you would have to change all switches.
     
  7. ericmark

    ericmark

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    The ways of a switch are the positions it moves to not counting off, so a flick switch with centre off is not considered as three way only two way, you can get three way switches, but not seen any flick switches three way, mostly they are rotatory switches, I have one on my oven to select which elements are used, I think 12 way from memory.

    So standard two way switching named after the switches it uses is two-way-real.jpg but in school we were taught two-way-school-boy.jpg both work, but the former means no connectors in the switch. This can be extended two-way-plus-inter.jpg to include a change over switch, also called reversing switch or intermediate switch. Some dimmers have the switch and dimmer with independent contacts so in the first diagram the right hand switch could be a dimmer.

    However you should not dim halogen lamps as it causes them to go black and reduces their life, and compact fluorescent is rare to find one which can be dimmed, so the dimmer switch went out of popularity and we started splitting the lighting, either wall and central, or central split 1/3 and 2/3 which gives three levels of lighting with two switches.

    With the LED bulb dimming is possible again, and the EU law said the package needed to say if the bulb was not dim-able, but it did not say the manufacturer had to stipulate how it could be dimmed. There are two things included with most LED packages, one is a leak resistor, AC can pass with capacitor and inductive linking so it is possible the wire to switch can act as a capacitor and send some power to light even when switches off, the resistor is bulb leaks this away, but dimming switches with no neutral add to this small current and if can build up and cause some bulbs to flash when switches off. The second is the bulbs when switches on can shimmer this is stopped by using a capacitor inside the bulb, but no information is given to size of leak off resistor or capacitor size, so some times it can result in flashing or a shimmer.

    Also all this results in LED bulbs not being as efficient as they could be, some are only 75 lumen per watt, but some smart bulbs can be up to 100 lumen per watt, so in general there has been a move away from dimming switches and using smart bulbs instead, specially since you can also set the colour temperature or even the colour.

    But the smart bulbs are also a mine field, some of mine are Zigbee and need a hub, some connect direct to wifi, and with mine all use same app on phone called smartlife. With zigbee they can be linked to a remote control and I have a set of bulbs in wife's bedroom worked by a zigbee remote one a wall light the other a table lamp. Her ceiling lights are G9 and not found smart G9 bulbs so that still uses an energenie smart wall switch, I had 5 of those switches, now down to 2 as they failed. And when they failed it was a pain finding a standard switch and turning off all lighting power to change the switch, far easier if a bulb goes wrong, I can swap without turning off all the lights, same with smart sockets.

    As yet cross fingers no smart bulb has failed, but a year ago would have said that for smart switches as well.

    The Lidi remote control comes with a back so can be screwed to the wall if required just like a standard switch, but held with a magnet so can be also removed when you want, I prefer remote controls to using phone, the Lidi remote was simple, Lidi-remote.jpg but only sold with GU10 lamp unit and three GU10 lamps, you can get a more complex remote Lampandremote.jpg but gets more costly, I have these Remote control.jpg remotes with energenie 4 independent controls and I tried to get one for rest of zigbee Remote1.jpg but simply can't get it to work, and this is my problem I don't walk around at home with mobile phone in my pocket, when I get home it goes on charge, so prefer a remote control as side of bed or on coffee table to turn lights on/off.

    The main light in living room has 8 bulbs, so that would be rather expensive to use smart bulbs in, I have a new fitting for top of stairs with a smart relay in it, once fitted I will say how it works, but as yet still in the box, theory is two way switches converted to extra low voltage and the 5 GU10 bulbs split to centre and 4 around outside with centre being colour changing so we can have 1, 4 or 5 bulbs lit, and can switch with phone or wall switch. But not fitted yet. Need a ladder to do the job.
     
  8. Greggerly

    Greggerly

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    @ericmark i have exactly same problem. use few smart bulbs but they are mostly for a pre-prgrammed mood settings. for the living room (where i have spotlifght bar) i want to be able to control them without alexa or my phone (it always take me a while to find it at home so not the best way to control light). i will look into the master slave dimmer switches. will give it a go to check if my spotlight will work or not. if not i might just drop the idea and focus on few small lamps around.
     
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