Two-way switches and strange wiring question

SeanRhodes · Jul 31, 2022

Hey all,

I'm trying to restore some switches in a house that's only nine years old in place of some terrible motion sensors.

History is quite unknown, but considering the placement of some switches, it seems the developer is somewhat to blame for the peculiarity!

All the wires behind where the switches used to be were mostly merged. So far, I've managed to unstitch these, get power to every device (light, smoke alarms, doorbell etc.) apart from two problems.

1. Bedroom - there are two single switches in this room (photos labelled S1 and S2). S1 works at controlling the light, but S2 does nothing. I've double-checked which wireless these are but can't deduce what position they should be in.

Notably, two brown wires in the com port of S1 seem to provide power to the en-suite.

2. Hallway - there a two double switches; the double located by the door (S1) controls the outside light and the hallway light. The second switch (S2) should control the landing light - but that's currently stuck on.

Notably, the power for the downstairs toilet, smoke alarm and doorbell run from here.

I've done a fair bit of reading on wiring standards, but it seems that what I'm dealing with isn't consistent - like the two-way switch in the bedroom, surely, both sides have intermittent lives...

I'm kinda hoping that someone would be able to give me a pointer as to what to try - as I'm so close, it would really bug me not to finish it all myself

Many thanks!

davesparks · Jul 31, 2022

You have a lot of exposed copper there and what looks like some damage to the insulation on one of the brown cores in the first picture which is also exposing the live conductor.

As a result what you have there could be quite dangerous and I suggest you consider getting an electrician to sort it out rather than continuing as you are.

At first glance it appears that all of the necessary cables are present and it should be quite a quick job to reterminate them and get it all working as it should.

Dustydazzler · Jul 31, 2022

Looks like someone stripped those cores with an axe

timhoward · Jul 31, 2022

Some general points first:
-try and terminate the wires so no copper is showing
-one of the wires in the pic S1 is damaged and the extent of the damage needs checking. It could be anything from just needing sleeving to a complete break (and possibly part of your problem)

[ElectriciansForums.net] Two-way switches and strange wiring question

S2 is wired fine (other than too much copper on show) and S1 just needs to match.
S1 - the cable that has the three wires coloured brown, black and grey needs to match S2.
There are three remaining wires: permanent live in, permanent live out (to next light) and switched live which turns the light on. Are you able to safely identify all of these and assess the damaged cable? If not then I'm afraid you need some help.

The Hallway one is too complicated to comment on without seeing how the cables are grouped.

littlespark · Jul 31, 2022

Any forum member down your way (Surrey?) that could pop in and sort it?

davesparks · Jul 31, 2022

littlespark said:
Any forum member down your way (Surrey?) that could pop in and sort it?

I hadn't even thought to look at their location, I'm just up the road in Woking.

brianmoooore · Jul 31, 2022

Lovely bit of workmanship from the original electrician. 25mm boxes in positions that would easily take 35mm, plus the unused tabs not bent flat. It's one of those that's probably responsible for the damaged wire.