Advice needed electric circuit not working

Hi

We've finally got round to installing LED plinth lights in our kitchen, the electrician had wired it all up bar needing to do the final connection in the light switches, leaving us to install the LED strips.

There are two areas of the kitchen that he wired up and one section works the other doesn't and we can't work out why, I'm hoping someone can help as the electrician doesn't answer his phone or get back to us (tried couple of times months before lockdown started).

The switches for the lights are number three and four


Both had the live wire at the top needing to be connected which we have done. The lights the third switch controls work the lights for the fourth don't. We have tested the cables for the fourth lights and there is no power going to them but the switch wiring in the box does have power.

I have a vague recollection of maybe needing to connect the two switches together but it was so long ago I can't remember and don't want to try unless sure it's correct.

Here are some close ups if it helps, I can take more photos if needed

Switch 3

Switch 4

Thanks in advance

Your first job is to find the other end of the cable supplying the leds. You'll need a multimeter, a long bit of single core flex (or a friend) and a torch cos you do this with the power off (not just the lightswitch).

Or you could just assume that the dimmer in the middle of switch 4 (is it meant to dim the plinth lights) is FUBAR so bypass it & see what happens- again isolate power first.

Sorry that maybe wasn't very clear it's the 3rd and 4th switch in the first photo, the other 4 switches are for lights which all work perfectly well. In the second photo it's the third switch along and in the third photo it's the first switch ( 4th out of the six).

Hope that makes sense

Bit more investigating and info

The LED lights have several different cables for them as it's not one continuous run


There is one cable under the island, two cables (one for each side) for the floor cabinets either side of the cooker and then two cables for each set of wall cabinets either side of the cooker, 7 cables in total for this part.

We have found one of the cables for the wall units on the left hand side of the cooker has power, none of the other cables do, pic below.


It feels like something somewhere in the circuit is not connected up but the electrician had only talked about the connecting up in the switch when we ready not anywhere else.

All of the lights, island plinth, floor cabinet plinth and wall cupboards should be switched on by one light switch.

First thing (this is important) if you're using a neon screwdriver to determine power/no power then please stop- they can occasionally be useful as a guide but are not reliable enough to trust with your life.
Get a multimeter
Isolate that circuit and check for dead.
Using that meter, verify that the non-live cable of that pair by the wall units is going to some more of your led stuff. When you've done that, connect the 2 cables together (brown to brown, blue to blue, cpc to cpc with sleeving) either in a junction box or more likely in the led driver thats going on top of that cupboard

Is there a single grommet in those back boxes?

Why aren't the earths dressed neatly round the perimeter of the boxes?

The supply lives of all the switches probably need to be linked together, but that shouldn't be done until all the wiring is tested and your electrician should be doing that as part of the certification process.

Is it mains LED strip or feeding a driver unit, just a thought he may have got a reel and cut it needing a further driver for a second run if you have more than one.