Replacing loop in at switch with WiFi switch

Edward Morris · Jan 27, 2019

good evening.

I have recently acquired a Sonoff T1 UK wifi light switch which requires a neutral wire for permanent power to the switch electronics. I would like to fit it to a 1-gang 1-way switch that I currently have in my bedroom, which is switching two light roses. The house is modern and was built in 2014 and conforms to the latest standards.

[ElectriciansForums.net] Replacing loop in at switch with WiFi switch

After removing the current light switch, I think I am right in determining (although I am not an electrician), that the switch has been installed with "loop in at the switch", as the diagram shows above. I have taken a few photos of the layout below, which I pretty sure is what is shown in the diagram. Coming into the light switch are three cables with brown lives, blue neutral and earths. Two of the brown lives are connected together into the COM terminal, and a single brown live into the L1 terminal. All three blue neutral wires are connected to a chocolate box with two terminals, with the other containing the three earths.

In order for the wifi light switch to work, it needs a continual power supply regardless of the state of the switching light circuit. Hence I need to get a neutral wire into the light somehow. Here's a diagram of the back of the unit.

So, this is how I interpret I can do this:

1. Put the COM connected dual live wires of the ring main into the permanent live terminal Lin.

2. Connect the L1 switched live of the lights into the switched live terminal Lout.

3. Ideally, get the 3 blue neutrals in the chocolate box into the Nin terminal. However, as the terminal is quite small and the wires are quite chunky, is it ok to put a small bridging wire from the chocolate box terminal connecting the 3 neutral wires, into the neutral terminal of the switch?

Nebu1a · Jan 27, 2019

You say the switch controls 2x ceiling roses. If the switch is at the end of the circuit the 2x browns in the common terminal maybe the switch lines to the roses. If the switch is mid circuit they may be permanent lives. You need to identify what is what with a voltage tester and then proceed. Perm lives to L in. Switch live to L out. and a neutral fly lead is ok.

littlespark · Jan 27, 2019

This is a fairly straight forward job, but I think you are a little confused with your terminology. (ie, lights are not wired in a ring formation)
Your 1,2,3 explanation is exactly right. The 2 browns currently in Com will be permanent feed to Lin of the new switch.... The single brown from L1 goes into Lout and the neutral is just a flying lead from the choc block.

However, @Nebu1a does have a point. It may be one feed and a switched live going to each rose. You'll have to check on that.

I also wonder why the choc block was used for the neutral when there was a N loop terminal on the switch itself?

Please make sure you isolate the circuit fully before working on it.

DPG · Jan 27, 2019

littlespark said:
I also wonder why the choc block was used for the neutral when there was a N loop terminal on the switch itself?

Please make sure you isolate the circuit fully before working on it.

Sparky not familiar with switches with a neutral loop connection point maybe?

Edward Morris · Jan 27, 2019

Nebu1a said:
You say the switch controls 2x ceiling roses. If the switch is at the end of the circuit the 2x browns in the common terminal maybe the switch lines to the roses. If the switch is mid circuit they may be permanent lives. You need to identify what is what with a voltage tester and then proceed. Perm lives to L in. Switch live to L out. and a neutral fly lead is ok.

Thanks so much for the advice.
The thought did cross my mind that the two ceiling roses could be complicating the issue a little bit.

Edward Morris · Jan 27, 2019

littlespark said:
This is a fairly straight forward job, but I think you are a little confused with your terminology. (ie, lights are not wired in a ring formation)
Your 1,2,3 explanation is exactly right. The 2 browns currently in Com will be permanent feed to Lin of the new switch.... The single brown from L1 goes into Lout and the neutral is just a flying lead from the choc block.

However, @Nebu1a does have a point. It may be one feed and a switched live going to each rose. You'll have to check on that.

I also wonder why the choc block was used for the neutral when there was a N loop terminal on the switch itself?

Please make sure you isolate the circuit fully before working on it.

Thanks for the advice, much appreciated, including the safety concern.

With regards to your point about the neutral wiring, I had the same question regarding why they weren’t in the loop terminal on the switch. I just assumed that it was easier to get into a choc box than the switch terminal, owing to the combined wire gauge.