Identifying wires

[skykit]

Hi all,
I am in the process of installing home automation modules - the light switch ones being modules that fit to the existing switch. Having done all the bedrooms which used dimmer modules, these were simple enough and obvious enough but relay modules are a little challenging because I'm either not seeing what wire does what or ...well I have no idea.

The house is a 2015 build so modern day wiring codes
In this case, I'm joining the module to a two-way switch where neutral exists in a block. Here is what I have found looking at both upstairs and downstairs switch:

Upstairs:
L1: Black with brown sleeve
L2: Grey with brown sleeve AND Light brown wire
L3: 2x Brown wires

Downstairs:
L1: Black with brown sleeve
L2: Grey with brown sleeve
L3: 1x brown wire

I'll leave out earth (screwed to the backbox) and neutrals (in the block) as these are obvious enough

Is this easy enough to identify what wire does what (ie: switched/perm live etc)
I do have a volt meter coming in but thought given the module is partly connected up, I could make this safe and finish it rather than wires sticking out (fuse switch is off though for upstairs lighting)

Annoyingly, I did have a qualified electrician put one of the relay modules in and it's a one-way switch so it does not quite match up - with that, I also did one other but again single switch so it was easy enough.
In attempt of doing the 2-way, he gave up after 2 hours of trying but this has led me more into questioning whether he knew what he was doing

Appreciate the help on this

 

[EFLImpudence]

Upstairs:..............................................................Downstairs:
L1: Black with brown sleeve.....................................L1: Black with brown sleeve
L2: Grey with brown sleeve......................................L2: Grey with brown sleeve
......(Light ?) brown wire...............
L3: Brown wire.......................................................L3: 1x brown wire
......Brown wire...........................

The wires from downstairs will be in the same sheath (same cable) and

the other two browns (one you call light brown) in another sheath - these will be the Permanent Live and Switched Live. Can't tell which.

 

[skykit]

Perfect thank you for the quick reply
I am due home a bit late tonight being bogged down with man-flu but this should solve the issues I have been having with the module
Will update either way and the volt meter should identify which of the two brown wires is live and which one is switched live along with checking which sheath has what coming out

 

[ban-all-sheds]

Using a volt meter to identify conductors by looking at the voltage on them is a foolishly and unnecessarily dangerous way to to it.

Check for continuity with the power off.

 

[skykit]

EFLImpudence Just wanted to say thanks again for confirmation. Everything went in fine and all the lights in the house are now automated be it via mobile, laptop, motion sensor or all 3.

thanks again!

ban-all-sheds - Thanks for your input too