Smart Switch Installation: Convert existing 2-way switch into 1-way switch?

[joeu25]

Sorry for the long first post, I wanted to be as thorough as possible.

On my landing I have a 2-way switch setup, one of which is 3-gang, one of which is 1-gang, and I’m looking to replace them with smart switches. I’ve purchased a few BroadLink LC-1 switches based off the recommendations of various online sources.

The 3-gang controls bathroom downlights, bathroom extractor fan, (which has a separate isolator switch) and landing lights.

The 1-gang controls the landing lights. (So only the landing lights are 2-way). The smart switches I have purchased do not require neutral wires - but neutral wires are present behind the 3-gang switch, they’re just all terminated together in a terminal block.

I took the 3-gang off the wall, and realised it was a bit more complex than I expected it to be. So I started with a 3-gang 1-way smart switch in my kitchen, a bit simpler, which went smoothly and gave me the confidence to now re-visit the switches on the landing.

My research has led me to believe that in order for this to work, (due to the nature of how smart switches are designed), the original circuit needs to become 1-way, keeping the 3-gang switch controlling everything, and removing the 1-gang switch from the circuit entirely. I then need to purchase what is effectively a ‘remote’ smart switch, to install in-place of the existing 1-gang. Through ‘smart scenes’, this ‘remote’ switch will effectively send a signal to the 3-gang switch telling it to turn on the lights. The 1-gang wouldn’t actually be connected to the circuit, as such.

What I can’t quite figure out, is whether I must terminate the existing cabling running to the 1-gang, and install a battery-powered ‘remote’ smart switch (not ideal), OR, whether I can somehow power a 1-gang smart switch there using the existing cabling that runs between the switches. (Preferred, if at all possible).

The smart switch has L, (mains live) then L1, L2, L3 for the lights/extractor/lights.

I’ve included a photo of the existing 3-gang switch along with my assumptions of what everything is. If anyone can advise on whether I’m on the right track, it’d be much appreciated.


From left to right on the back of the switch:

Landing lights (2-way), extractor fan, Bathroom lights
Starting with bathroom lights: L1 comes in from the left of the backbox, only 2 other wires connect to the switch from here: the brown wire going into COM of bathroom lights, and the black wire going into L1 of extractor fan.

I’m therefore assuming that the wire from left of backbox into COM of bathroom lights (far right gang) is the main live wire, and the wire in L1 is switch-live for bathroom light ring. Is this correct? But then why does a wire also come into this COM from the opposite site of the backbox?

I’m also assuming the black wire in L1 extractor fan (centre gang) is the switch-live to the extractor, and the feed into centre COM provides mains live.

This leaves the left gang, for the landing, which is blowing my mind. My assumption is that 3 of these wires connect to the other switch.

Im assuming grey wire in L2 needs terminated, and the link coming in from centre COM should swap from L2 to COM, terminating the brown wire in COM currently. This leaves a black and a brown in L1 - which of these should be terminated to complete the shut-off of the other switch? And why are there 8 ‘incoming’ wires connected to this switch? It seems like 1 more than it should be.



Any and all insight or advice much appreciated.

 

[littlespark]

Very difficult to describe in text what needs to happen here.

Draw it all out on paper so you know which cable is which.

Can you post up a picture of the back of the smart switch, and the wiring diagram on the instructions that came with it.

The brown/black/grey on the 2 way should run directly between this switch and the other 2 way position. (This is how you can get power to the slave switch)


Do you think you can connect it up as 3 one ways at the moment? Disconnect and ignore the 3 core I’ve mentioned for the time being.

Once we see the instruction diagram… we can tell you where to stick them.



From experience… any signal being sent from slave to master will only be 6 volts or something small.
I had a customer connect up his own smart switch, left the original other switch in place…. Sent 230v along the signal line a fried the rather expensive master switch.

Not all are like that, but something to be wary of.

 

[joeu25]

Thanks for the quick reply on this, I've attached here diagrams of both switches.

The 2-way circuit has 2x light fixtures on it, so I am assuming this is why there are 2x 4-core cables at the other switch?

The smart-switch, I've discovered, cannot be used as 2-way. This is fine, I'm happy to convert the 3-gang into a 1-way switch, effectively making the other switch (the 1-gang) completely disconnected from the circuit.

I've also attached an image of the smart switch and the instructions that came with it. (Blu-tack is just there to hide the pairing QR code).

 

[telectrix]

First Ì,ď disconnect both 1 way switch wires and make ènds safe with terminal bloocks

I would have been inclined to put a charge on her house- you will get the money back eventually but it will cost her wellmore than £300 for a lawyer to remove the inhibition and it will hold up the house sale.
The £300 will alsoi8 grow at 8% (statutory interest)

Yes, I am petty.

safe

 

[joeu25]

First Ì,ď disconnect both 1 way switch wires and make ènds safe with terminal bloocks


safe

Do you mean all 4 of the wires coming into the 1-gang switch that I want to disable for now?

What happens with the 2x brown ones which are connected together?

 

[joeu25]

Darn - I’ve just remembered that this switch is actually THREE way. There is another 3-gang controlling these lights at the bottom of the stairs. It’s hidden by a storage unit, so it is literally never used. No wonder I forgot it was even there.

So, looking at the photos I have already shared, keeping in mind there is another switch on this circuit at the bottom of the stairs; what is the best course of action?