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Replacing a 3 Gang 2-way light switch with a new Smart Switch

Postby Bonkers » Fri Dec 04, 2020 3:41 pm

I all, would really appreciate some help on this. Non sparky with no clue.

I have a 3 gang light switch in the the downstairs hallway.
switch 1 controls the outside light
switch 2 is the downstairs light
switch 3 is the upstairs landing light, this can also be switched on/off with the switch upstairs.

bought a "3 gang 2-way Wifi integrated switch". different layout and labels. Can anyone help me with how to wire this up?

See pics for existing and new switch, with a pretty hand drawn wiring diagram :) hopefully that's enough info.

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Simply Build It

Postby Mr White » Fri Dec 04, 2020 7:53 pm

Sorry to tell you, but you have made the "classic mistake" of assuming you can change a light switch to a smart switch with no trouble.

Smart switches (most) need power to work, they get this from the lighting circuit supply, Live and Neutral.
You can clearly see your new switch has terminals marked L and N
sadly you have not got neutral at your switch, 90% of houses don't so you are not alone.

Sorry but you are going to have to send it back and get a refund, short of a rewire, there is nothing you can do.

There is a 2 gang smart switch that requires no neutral but you need 3 gang.
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Postby ericmark » Sat Dec 05, 2020 1:52 pm

As Mr White says, I have only seen two gang switches which don't need a neutral, and they are also expensive.

MIHO001 Gateway £40 approx
MIHO090 Switch pair £50 approx

And even then not perfect, any electronic light switch needs power to work, those without a neutral pass a small amount of power through the bulb even when off, this works fine with a tungsten bulb, but with LED or compact fluorescent the bulb has to be designed to dim even if not dimming the bulb, and there are two common problems.

1) flicker when on, only cure is try another make of bulb.
2) will not switch off fully or flashes when off, you can fit load capacitors to stop this.

Also you can get interference, we fitted one smart light switch great, used a remote control at bed side to switch on/off from bed, but then expanded to five, at which point started to get problems, switch locking and would not switch on or off, and switching on or off on it's own, we removed two smart switches and remaining three work OK.

Also using smart devices, we have Nest Mini which in theory should work the lights, and yes we will say "hay google turn off music" and it replies "turning off five switches" and turns off the lights, the command "hay google turn lights back on" gets "I don't know how to do that yet." just acts like a naughty boy.

My son says his Amazon Echo works OK, but he does not have many smart devices, and it seems to start with they are OK, but as you add devices then they play up.

In the main mine have settled down, but every so often we will find a socket, light, or TRV has done something daft. And when we got the TRV heads they were advertised as working with Nest, but since then google has taken over and Nest has withdrawn support.

I have tried doing the same as Nest, and have said to wife "There has been an error, try again latter" but she will accept it from Nest, but not from me, it a "get up and make me my coffee now your not google" and the mini says "did not get that, please try again" which does not help.
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Postby Bonkers » Sun Dec 06, 2020 12:57 pm

thanks guys, i had a feeling I'd got this totally wrong.
just a thought, could i swap out the 3 gang switch for a 2 gang smart switch, then wire the outside light to be permanently live? or is that a really bad idea?
i have a smart bulb in the outside light and the whole reason i was attempting this was to make the outside light smart and so the family didn't keep turning the outside light off at the switch, which would cause it to disconnect from the wifi.
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Postby Mr White » Sun Dec 06, 2020 9:05 pm

Why not leave the light on and put tape over the switch?
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