Replacing switch with a dimmer in a 3 way installation

Greggerly · Post by **Greggerly** » Mon Sep 20, 2021 7:24 pm

Hi guys.

Trying to install 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 stair.

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

ericmark · Post by **ericmark** » Mon Sep 20, 2021 8:29 pm

The dimmer switches can come as master slave, and there is a limit on how many, but quite a large limit. The wiring is completely different to a using two way and intermediate switches.

However there seems to be a problem with LED lights, not all LED lights are the same, some use a capacitor to limit current and some use pulse width modulated chips, the size of the leak resistor, and size of smoothing capacitors vary, so there is a problem with lights flashing when switched off and a shimmer when on, better to use smart light bulbs if you can.

Neelix · Post by **Neelix** » Mon Sep 20, 2021 8:35 pm

Sounds like the switch you want to change is an intermediate. Is there another pair of cables connected together in the back box?

Someone-Else · Post by **Someone-Else** » Mon Sep 20, 2021 9:41 pm

The new switch must have the same terminal markings (Or very similar) to the existing switch

Greggerly wrote: ↑Mon Sep 20, 2021 7:24 pmThe 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.

So you can not change the switch with the dimmer that you do have.

Sometimes it is possible to change one of the "end switches" (The living room switch has been wired up so that it is in the middle of 3 switches) BUT the dimmer you have is 1gang 1-way so it is of no use in this situation.

Also, if you have LED lamps, you should check are they dimable, as not all are.

Another point to note with 3 way switching and one dimmer, if you do change an end switch, obvious that it is, if you dim the lights down, and switch the lights off from another switch as you go to bed (That bit is not a problem) when you next turn the lights on you will find they are too dim (They are still dimmed from last time) you have to go to the dimmer and turn the lights up, in theory it is not a problem, but after a few days of doing this it soon becomes annoying, so you change it back.

There is actually a wireless dimmer switch available, it would have to sit adjacent each of your existing switches, you would need access to above the light (Take it down for a short while, while you connect the receiver) and it can only dim 100watts, it is called Quinetic

ericmark · Post by **ericmark** » Wed Sep 22, 2021 2:08 am

I note with some of my smart bulbs, if turned off on the app, turning off lights and turning them on again switches bulbs back on.

The big problem I find with LED lighting is the adverts don't tell you what you need to know.

Greggerly · Post by **Greggerly** » Wed Sep 22, 2021 6:30 pm

thank you guys. i do know now that i will need to focus on master / slave dimmers. there are few on the market that potentially can work.
but as mentioned i will need to check on the LED's if they will work with this perticular dimmer switch.
i use smart bulbs on few lamps but in this case i have a LED bar with spotlights so dont think there are any alternatives for GU10 bulbs. so i either go for the master / slave arrangement or quite the idea altogether

ericmark · Post by **ericmark** » Sat Oct 02, 2021 3:15 pm

I have a light bar from Lidi which uses GU10 smart bulbs and it even came with a remote control to switch on/off or dim bulbs, however it was zigbee so needs a hub to work the bulbs.

The remote has a holder which is magnetic so can be wall mounted, the rub is they don't sell the remote on its own.

ericmark · Post by **ericmark** » Tue Oct 05, 2021 2:55 pm

I have a chandelier wife wants above the stairs, we want the ability to turn on/off with wall switch, but also with our phone, so I bought a zigbee relay

: DSC_6060.jpg (168.66 KiB) Viewed 1447 times

I was not sure how it would work, it has both low voltage and extra low voltage connections

: DSC_6061.jpg (195.07 KiB) Viewed 1447 times

the extra low voltage goes to the switch,

: DSC_6062.jpg (194.18 KiB) Viewed 1447 times

I split the wiring so centre bulb independent from outers

: DSC_6059.jpg (170.69 KiB) Viewed 1447 times

: DSC_6058.jpg (171.3 KiB) Viewed 1447 times

so I can either have one light four lights or five lights, the wall switch switched lights on/off with a change of state, it does not matter if on or off, flicking the switch changes it as does the phone app, so the phone is like another intermediate switch.

I did a test as was not sure with instructions if it needed a momentary switch or simple on/off, and it does use a simple on/off.

Note it does need a zigbee hub.