Lights - Why is the my supply switch controlling my new one?

[kreatiff63]

I've taken the supply from a neighbouring light [power source = outdoor lights] and this now controls the old and new switch as follows:

• When I turn on the new lights the outdoor lights come on with a low glow
• When the new lights are turned on and I turn on the outdoor lights, this turns the new lights off, why?
  
  
• The brown cable from the power source goes to L2 = live,
• the blue cable from the power source goes links to the blue cable cable going to the lights.

This is the wiring diagram I used for the fitting of the intermediate switching

 

[UNG]

I've taken the supply from a neighbouring light [power source = outdoor lights] and this now controls the old and new switch as follows:

• When I turn on the new lights the outdoor lights come on with a low glow

This would suggest that you have the lights connected in series

• When the new lights are turned on and I turn on the outdoor lights, this turns the new lights off, why?

This suggests that turning on the outside lights is removing the live feed from the new light

• The brown cable from the power source goes to L2 = live,
• the blue cable from the power source goes links to the blue cable cable going to the lights.

How have you verified this

This is the wiring diagram I used for the fitting of the intermediate switching

View attachment 103170

What does the intermediate switching control, the diagram you have posted looks to show the blue cable at the light with a brown sleeve

Can you post a diagram of what you have actually done with some pictures of what you have connected where

 

[kreatiff63]

This would suggest that you have the lights connected in series

This suggests that turning on the outside lights is removing the live feed from the new light

How have you verified this

What does the intermediate switching control, the diagram you have posted looks to show the blue cable at the light with a brown sleeve

Can you post a diagram of what you have actually done with some pictures of what you have connected where

Thanks for your quick reply, I'll do my best to answer:

1. Yes, they're not meant to be, which leads me to think that the supply which comes from the neighbouring switch is taking part in the circuit somehow. I don't know how to prevent that given the drawings, which btw i think show how to take from the consumer unit. I'm not, but I am using a one way switch in the same 4gang switch.
2. Yes, I would agree, and goes the shared agreement that the source is somehow involved in the loop, though it's not meant to be...
3. Trying the different light switches, if that's what you meant?
4. The intermediate switch works correctly as do the other lights in the 3 way system. The brown sleeving is a hangover from the original diagram taken from here https://www.youtube.com/c/GSHElectrical and doesn't act as a switching line or at least that's not my intention
5. The pictures are difficult to intepret because its a 4 gang switch and its difficult to tell precisely whats doing what. However the diagrams I'm happy to supply. Though again I'm thinking that its easier if I just tell you. It's 2 way switch in a 4 gang plate which is wired to the com and L1 terminals. I've fed the live from the com and the 'neutral' from L1. The 'neutral' from source is connected to the 2 core lighting cable and doesn't connect to the new switch terminals. The live feeds into L2 in the new switch.
   
   OK I've worked on one image to get you a close up of the neighbouring switch and new 3 way switch.
   
   Things to note are:
6. the 'live' is a single wire because I've used a wago to split the live into two - 1 feeding the new switch and 1 feeding the existing one way light. This makes no impact on the outcome other than making it easier to connect up.
7. The blue cable connects to the lighting blue cable
   
   

 

[kreatiff63]

This would suggest that you have the lights connected in series

This suggests that turning on the outside lights is removing the live feed from the new light

How have you verified this

What does the intermediate switching control, the diagram you have posted looks to show the blue cable at the light with a brown sleeve

Can you post a diagram of what you have actually done with some pictures of what you have connected where

I'm thinking I have two options:

1. Bite the bullet and get a feed from the consumer unit.
   
   
2. Only use the 'live' feed from the neighbouring light, but I don't know if this is safe, nor if it would work, nor what to do with the 'neutral' that is meant to be feeding the light - i guess this would have to connect to the switch - no idea which terminal

 

[UNG]

I'm thinking I have two options:

1. Bite the bullet and get a feed from the consumer unit.
   
   
2. Only use the 'live' feed from the neighbouring light, but I don't know if this is safe, nor if it would work, nor what to do with the 'neutral' that is meant to be feeding the light - i guess this would have to connect to the switch - no idea which terminal

Actually you do have 4 options

The two you posted

Or do what I suggested in post #2

Or the response most DIYers don't like which is get a spark in to sort the problem out

 

[UNG]

Thanks for your quick reply, I'll do my best to answer:

1. Yes, they're not meant to be, which leads me to think that the supply which comes from the neighbouring switch is taking part in the circuit somehow. I don't know how to prevent that given the drawings, which btw i think show how to take from the consumer unit. I'm not, but I am using a one way switch in the same 4gang switch.
2. Yes, I would agree, and goes the shared agreement that the source is somehow involved in the loop, though it's not meant to be...
3. Trying the different light switches, if that's what you meant?
4. The intermediate switch works correctly as do the other lights in the 3 way system. The brown sleeving is a hangover from the original diagram taken from here https://www.youtube.com/c/GSHElectrical and doesn't act as a switching line or at least that's not my intention
5. The pictures are difficult to intepret because its a 4 gang switch and its difficult to tell precisely whats doing what. However the diagrams I'm happy to supply. Though again I'm thinking that its easier if I just tell you. It's 2 way switch in a 4 gang plate which is wired to the com and L1 terminals. I've fed the live from the com and the 'neutral' from L1. The 'neutral' from source is connected to the 2 core lighting cable and doesn't connect to the new switch terminals. The live feeds into L2 in the new switch.
   
   OK I've worked on one image to get you a close up of the neighbouring switch and new 3 way switch.
   
   Things to note are:
6. the 'live' is a single wire because I've used a wago to split the live into two - 1 feeding the new switch and 1 feeding the existing one way light. This makes no impact on the outcome other than making it easier to connect up.
7. The blue cable connects to the lighting blue cable
   View attachment 103172

If my understanding of what you have done is correct the blue wire needs to be connected to a neutral, where it is currently connected gets a neutral through the light that is fed by the red wire which is why they work dimly and when the switch is on your new lights have 2 lives feeding them and no neutral, quite a simple fix you just need a neutral to connect to you may be lucky and have a looped neutral feed in the switch back box

 

[kreatiff63]

If my understanding of what you have done is correct the blue wire needs to be connected to a neutral, where it is currently connected gets a neutral through the light that is fed by the red wire which is why they work dimly and when the switch is on your new lights have 2 lives feeding them and no neutral, quite a simple fix you just need a neutral to connect to you may be lucky and have a looped neutral feed in the switch back box

"...you may be lucky and have a looped neutral feed in the switch back box"

Sorry, but I don't undertand this... I'm guessing you could mean I might have another neutral I can take from another switch?

 

[kreatiff63]

Actually you do have 4 options

The two you posted

Or do what I suggested in post #2

Or the response most DIYers don't like which is get a spark in to sort the problem out

Reluctant to try my single cable com feed because the neutral bothers me, as in the original diagram clearly shows using the neutral. Although I have seen instances of where people use a single com feed from neighbouring light. The neutral from the light needs to go somewhere.

Post#2 - discuss more, I think I follow but want to be clear what you meant by that.

Pro's - I've tried to get a sparky in but I had quotes of £1000 for the works in three parts including hallway, kitchen, and conservatory. This was after I had one chap offer £250 for the day.

 

[Avo Mk8]

"...you may be lucky and have a looped neutral feed in the switch back box"

Sorry, but I don't undertand this... I'm guessing you could mean I might have another neutral I can take from another switch?

Apologies for jumping in - maybe a bit of context might help.
In older properties/ traditional wiring, you do not normally have neutral wires at light switches, all wires are live or swiched live one way or another. The neutral is taken directly to the light fitting only.

More recent installations may take neutral via the light switch position (ie looped through), because with the advent of smart switches, some require a neutral to work, so it's become more commonplace to make that provision for the future.

I suspect you may need to bring in a neutral connection - meaning from that lighting circuit - not any old neutral!

PS you say "The neutral from the light needs to go somewhere." That is the crux of the matter. I doubt you have a neutral at the switch. Just because there's a blue wire doesn't mean it's actually a neutral! If you have a test meter you can check.

 

[kreatiff63]

Thanks for your quick reply, I'll do my best to answer:

1. Yes, they're not meant to be, which leads me to think that the supply which comes from the neighbouring switch is taking part in the circuit somehow. I don't know how to prevent that given the drawings, which btw i think show how to take from the consumer unit. I'm not, but I am using a one way switch in the same 4gang switch.
2. Yes, I would agree, and goes the shared agreement that the source is somehow involved in the loop, though it's not meant to be...
3. Trying the different light switches, if that's what you meant?
4. The intermediate switch works correctly as do the other lights in the 3 way system. The brown sleeving is a hangover from the original diagram taken from here https://www.youtube.com/c/GSHElectrical and doesn't act as a switching line or at least that's not my intention
5. The pictures are difficult to intepret because its a 4 gang switch and its difficult to tell precisely whats doing what. However the diagrams I'm happy to supply. Though again I'm thinking that its easier if I just tell you. It's 2 way switch in a 4 gang plate which is wired to the com and L1 terminals. I've fed the live from the com and the 'neutral' from L1. The 'neutral' from source is connected to the 2 core lighting cable and doesn't connect to the new switch terminals. The live feeds into L2 in the new switch.
   
   OK I've worked on one image to get you a close up of the neighbouring switch and new 3 way switch.
   
   Things to note are:
6. the 'live' is a single wire because I've used a wago to split the live into two - 1 feeding the new switch and 1 feeding the existing one way light. This makes no impact on the outcome other than making it easier to connect up.
7. The blue cable connects to the lighting blue cable
   
   View attachment 103172

To anyone reading this... Do not take the neutral from a switching line (as in the pic). In this example, what I'm trying to do is take the power from a neighbouring light switch and extend this to the light, this doesn't work and may be dangerous. The 'power' in this sense also includes a neutral to the light. This needs to come from either a lighting loop, or the consumer unit. Anything else would be for the pros only.

 

[kreatiff63]

Apologies for jumping in - maybe a bit of context might help.
In older properties/ traditional wiring, you do not normally have neutral wires at light switches, all wires are live or swiched live one way or another. The neutral is taken directly to the light fitting only.

More recent installations may take neutral via the light switch position (ie looped through), because with the advent of smart switches, some require a neutral to work, so it's become more commonplace to make that provision for the future.

I suspect you may need to bring in a neutral connection - meaning from that lighting circuit - not any old neutral!

PS you say "The neutral from the light needs to go somewhere." That is the crux of the matter. I doubt you have a neutral at the switch. Just because there's a blue wire doesn't mean it's actually a neutral! If you have a test meter you can check.

yes, the blue cable is my handy work I'm afraid. I'm trying to bring the power supply and neutral to the switch, passing the neutral straight up to the light. But with my lack of knowledge, as I've seen examples in my own house where there is looping from one com to another and works for switches (perm/switching lines), I assumed that the other cable (not com) would be neutral. My error, I now know this was wrong. I therefore need to find a different supply either from a loop circuit in the attic (single storey), or take my power supply from the consumer unit. Was previously unsuccessfull in the attic. So...

Starting to get my head around getting a supply from here... obvs a B6 - old school Red/Black wiring. Any ideas how to do this?

 

[UNG]

Do you have any black cables in a connector block in the switch back box

An overall picture of the switch and back box may help

 

[kreatiff63]

Do you have any black cables in a connector block in the switch back box

An overall picture of the switch and back box may help

This is what the 4gang looked like before the move. The 1st and 3rd from the left are in use in new 4G in position 1&2. The 2nd & 4th don't exist anymore.

Just looking at the previous picture (below) from the consumer unit, i can see there is a neutral in a plastic connector is something I could use if i found its partner there too? Actually it looks like it goes to the unprotected right hand side of the rcbs

 

[Avo Mk8]

can the live and neutral come from different sources? Just looking at the picture i see there is a neutral in a plastic connector which I could share using those plastic clip connectors?

They need to come from the same circuit, by which I mean if your lighting circuit is the B6 breaker in the middle of the board (RCD protected) then the neutral needs to come from the middle of the three neutral bars (preferably terminal 4!).

There's also a B6 on the right, for a circuit which is not RCD protected, which I imagine you are not using for the lighting?

The neutral and live need to come from through the same RCD, otherwise you will have tripping problems!

 

[Avo Mk8]

Is there not an existing light fitting in the vicinity of where you want to put your new light, from which you could take the neutral. Or is the consumer unit nearer - it's unusual to resort to running singles from the CU!
If you do, once out of an enclosure, the cable needs to be of the sheathed type, like T&E covered in grey insulation, not just blue single insulated . I'm sure you know this.

 

[kreatiff63]

Is there not an existing light fitting in the vicinity of where you want to put your new light, from which you could take the neutral. Or is the consumer unit nearer - it's unusual to resort to running singles from the CU!
If you do, once out of an enclosure, the cable needs to be of the sheathed type, like T&E covered in grey insulation, not just blue single insulated . I'm sure you know this.

the CU is just behind the partition wall - the building is brick clad timber frame, so pretty easy to work with. The CU is about 1m away, but at 90 degrees to the current wall. It's an external wall as described. Hopefully the drawing makes sense...

 

[kreatiff63]

Is there not an existing light fitting in the vicinity of where you want to put your new light, from which you could take the neutral. Or is the consumer unit nearer - it's unusual to resort to running singles from the CU!
If you do, once out of an enclosure, the cable needs to be of the sheathed type, like T&E covered in grey insulation, not just blue single insulated . I'm sure you know this.

I've got this above the kitchen next to the hallway where I'm working. Looks like a bunch of live and neutrals... and what I need for my lights for both the hallway and kitchen. It looks like a lighting ring juction box with a switch cable coming from it?

Could I take my power source to my switch and neutral to the light (via the switch) as per my diagram from the spare slot on the right. And then could I also use this feed with wagos to provide L/N in the same way to my hallway switch? The switches are all in the same 4G light switch array.

Hmmm... I've just spotted that there are 2 cables coming in from the top, so there are four cables here... and there are brown and blue wires mixing. Any ideas which is which????

My guess...

• Bottom Right Terminal = Live
• Top Right Terminal = Earth
• Bottom Left Terminal = Neutral
• Top Left Terminal = Switched Live

 

[Avo Mk8]

I would hazard a guess that top left terminal is permanent live, because there's a through cable from top left to bottom, and thus the blue in the top left terminal is the L feed to the lightswitch (underneath cable at the top that returns the brown switched live to the bottom right terminal) and then the front top cable (neutral and switched live) goes to the light.

So I believe your list has top left and bottom right the wrong way round!

You need to be careful adding additional cables to those terminals, as it's easy to cross thread the grub screws when the terminal gets full, and also easy to break the head of the screw by tightening it too hard in an attempt to force too many wires in! (Not that I've ever done that) However I feel, given you're doing this anyway, it is a better place to take a feed from than the CU.

You should really get a 2-pole tester to use doing this stuff, to ensure you know what is what, not 'guess'!
Eg:

https://www.tester.co.uk/martindale-vt12-voltage-and-continuity-tester?

 

[kreatiff63]

I would hazard a guess that top left terminal is permanent live, because there's a through cable from top left to bottom, and thus the blue in the top left terminal is the L feed to the lightswitch (underneath cable at the top that returns the brown switched live to the bottom right terminal) and then the front top cable (neutral and switched live) goes to the light.

So I believe your list has top left and bottom right the wrong way round!

You need to be careful adding additional cables to those terminals, as it's easy to cross thread the grub screws when the terminal gets full, and also easy to break the head of the screw by tightening it too hard in an attempt to force too many wires in! (Not that I've ever done that) However I feel, given you're doing this anyway, it is a better place to take a feed from than the CU.

You should really get a 2-pole tester to use doing this stuff, to ensure you know what is what, not 'guess'!
Eg:

https://www.tester.co.uk/martindale-vt12-voltage-and-continuity-tester?

I've got this, is this one?

 

[kreatiff63]

I would hazard a guess that top left terminal is permanent live, because there's a through cable from top left to bottom, and thus the blue in the top left terminal is the L feed to the lightswitch (underneath cable at the top that returns the brown switched live to the bottom right terminal) and then the front top cable (neutral and switched live) goes to the light.

So I believe your list has top left and bottom right the wrong way round!

You need to be careful adding additional cables to those terminals, as it's easy to cross thread the grub screws when the terminal gets full, and also easy to break the head of the screw by tightening it too hard in an attempt to force too many wires in! (Not that I've ever done that) However I feel, given you're doing this anyway, it is a better place to take a feed from than the CU.

You should really get a 2-pole tester to use doing this stuff, to ensure you know what is what, not 'guess'!
Eg:

https://www.tester.co.uk/martindale-vt12-voltage-and-continuity-tester?

I mocked up this picture as I thought it was, but if you're right where would i be connecting up to for my supply/neutral to the switch?

 

[Avo Mk8]

Excuse the rubbish edited version below, which is my best guess at what you have.
Using the modified labelling(!) below - I'm thinking cable 3 is the supply from the lighting circuit (eg CU or another room), and cable 4 continues the supply to the next room/ item on the circuit. (or vice versa)
You could (carefully!) check with your meter that between the SW terminal and N is 240V with the relevant light switch on, and 0V with it off (though with your high impedance meter it may show some random ghost voltage rather than 0V) and that there is 240V permanently between L and N, irrespective of any or all light switch positions.

If the above test holds true then to feed your new light with a permanent supply: L, N and E as marked up below.

If the L to N voltage goes to zero when a light switch is tuned off - see edit below


View attachment 103257
OK - so a point of clarification - does this junction box feed two lights in two different directions?
Your original scheme makes sense if your cable 2 brings power in, cable 1 goes to the switch, and cables 3 and 4 go to lights.

 

[loz2754]

OK - so a point of clarification - does this junction box feed two lights in two different directions?
Your original scheme makes sense if your cable 2 brings power in, cable 1 goes to the switch, and cables 3 and 4 go to lights.

Exactly how I saw it

 

[Avo Mk8]

I mocked up this picture as I thought it was, but if you're right where would i be connecting up to for my supply/neutral to the switch?

View attachment 103247

So reassured by Loz's comment
If we've got the assumption correct, the supply terminals you need for your new light scheme are those marked N, L, and E in your diagram
The cable list at the bottom of the drawing would be:
#1 light switch
#2 incoming power
#3 to light (a)
#4 to light (b)
If you can confirm the above seems where the wires go, there is a good chance your illustration is correct.
Your multimeter (carefully) connected across your labelled L & N should still show about 240V when all light switches are off!

 

[kreatiff63]

Excuse the rubbish edited version below, which is my best guess at what you have.
Using the modified labelling(!) below - I'm thinking cable 3 is the supply from the lighting circuit (eg CU or another room), and cable 4 continues the supply to the next room/ item on the circuit. (or vice versa)
You could (carefully!) check with your meter that between the SW terminal and N is 240V with the relevant light switch on, and 0V with it off (though with your high impedance meter it may show some random ghost voltage rather than 0V) and that there is 240V permanently between L and N, irrespective of any or all light switch positions.

If the above test holds true then to feed your new light with a permanent supply: L, N and E as marked up below.

If the L to N voltage goes to zero when a light switch is tuned off - see edit below


View attachment 103257
OK - so a point of clarification - does this junction box feed two lights in two different directions?
Your original scheme makes sense if your cable 2 brings power in, cable 1 goes to the switch, and cables 3 and 4 go to lights.

FIRSTLY - MASSIVE THANKS FOR THE RESPONSES

Been upstairs and found THE junction box. It has to be the same one but the configuration is now different (Uhgg!!). However, there is I think good news, this ones easier to read... I can be more sure of whats what. AND I think I have found a power supply!

However, I think I need to wire up a new junction box feeding from this one. I need two neutrals (1 Kitchen / 1 Hallway), unless I can share this in a wago in the back of the 4G switch?

 

[Avo Mk8]

FIRSTLY - MASSIVE THANKS FOR THE RESPONSES

Been upstairs and found THE junction box. It has to be the same one but the configuration is now different (Uhgg!!). However, there is I think good news, this ones easier to read... I can be more sure of whats what. AND I think I have found a power supply!

However, I think I need to wire up a new junction box feeding from this one. I need two neutrals (1 Kitchen / 1 Hallway), unless I can share this in a wago in the back of the 4G switch?

View attachment 103291

Looks promising. Well done!
Normally the switch is in the live wire, so the light fitting is not live when you turn it off ! In which case cable 1 ought to be the switch and cable 2 the light - does that make sense?
It seems cable 3 is the permanent supply you need. You mention cable 3 comes from a Wago joint - could you put a Wago box or junction box there to take a feed from, or alternatively take a T&E to feed your new circuit out of the box you show here.

Note the long stripped bare copper on the black hanging out of the SW terminal - looks like it's falling out. I would try re-making that terminal (power off of course!) The idea is not to have any bare copper on display, so insulation should run up close to the terminals, and the E wires should have sleeving. Similarly cable 3 has some single insulated cable outside the junction box, which is poor practice. Appreciate this is not your fault, and you may know all this, but I just thought it worth pointing out if not!

You could normally accommodate a Wago for N's in the back of a deepish box, but with your 4 gang switch it might be tight? Can you not distribute the neutral to the lights above the ceiling (as per your very first diagram) - why take it to the switch box?

 

[kreatiff63]

Looks promising. Well done!
Normally the switch is in the live wire, so the light fitting is not live when you turn it off ! In which case cable 1 ought to be the switch and cable 2 the light - does that make sense?
It seems cable 3 is the permanent supply you need. You mention cable 3 comes from a Wago joint - could you put a Wago box or junction box there to take a feed from, or alternatively take a T&E to feed your new circuit out of the box you show here.

Note the long stripped bare copper on the black hanging out of the SW terminal - looks like it's falling out. I would try re-making that terminal (power off of course!) The idea is not to have any bare copper on display, so insulation should run up close to the terminals, and the E wires should have sleeving. Similarly cable 3 has some single insulated cable outside the junction box, which is poor practice. Appreciate this is not your fault, and you may know all this, but I just thought it worth pointing out if not!

You could normally accommodate a Wago for N's in the back of a deepish box, but with your 4 gang switch it might be tight? Can you not distribute the neutral to the lights above the ceiling (as per your very first diagram) - why take it to the switch box?

Well I now have kitchen lights, but a weird thing happened. I turned off all the lights and 16amp breakers too at the CU, and after connecting to the wago upstairs and feeding it back to the 4G downstairs I was trimming off the end for connecting and it cut off all the power, so it must have been 'live'.

But the strange thing is i know that the single light in the kitchen goes off when turn the light 6/16's off. Going to test it again now... the single spot went off. I tried the lights (kitchen pendants) and they were off. Going to try with the multireader. Getting power with the power on and not when off. Hmmmm maybe I didn't turn off all of the 6&16s at the CU, but I'm pretty sure I turned at least the one I needed to off.

Anything like that ever happen to you?

Going to tidy up and connect the hallway lights using a wago at the switch for the hallway lights too. BTW its a partition wall and there's plenty of room back their after nibbling at the insultation we used.

Another thing just occuring to me is that the L/N I've gone into is brown/blue. The cables at the CU are all red/black. However I still think we made the right call at JB. I guess its coming off another JB, and possibly a 32amp ring circuit (not my work)

 

[kreatiff63]

Looks promising. Well done!
Normally the switch is in the live wire, so the light fitting is not live when you turn it off ! In which case cable 1 ought to be the switch and cable 2 the light - does that make sense?
It seems cable 3 is the permanent supply you need. You mention cable 3 comes from a Wago joint - could you put a Wago box or junction box there to take a feed from, or alternatively take a T&E to feed your new circuit out of the box you show here.

Note the long stripped bare copper on the black hanging out of the SW terminal - looks like it's falling out. I would try re-making that terminal (power off of course!) The idea is not to have any bare copper on display, so insulation should run up close to the terminals, and the E wires should have sleeving. Similarly cable 3 has some single insulated cable outside the junction box, which is poor practice. Appreciate this is not your fault, and you may know all this, but I just thought it worth pointing out if not!

You could normally accommodate a Wago for N's in the back of a deepish box, but with your 4 gang switch it might be tight? Can you not distribute the neutral to the lights above the ceiling (as per your very first diagram) - why take it to the switch box?

So I have the live and neutral to the quick fit connectors keeping it to a single cable to the terminal in the switch. How would I go about connecting the live and neutral to the hallway lights using the single cable i have running to the 4G switch. Does it matter if they share the same 'connector' fitting. To be clear this is the type I'm using...

 

[Avo Mk8]

I was trimming off the end for connecting and it cut off all the power, so it must have been 'live'.

If you inadvertently shorted neutral to earth that can trip the RCD, even with that circuit's MCB off,
That is 'normal behaviour'

 

[kreatiff63]

So reassured by Loz's comment
If we've got the assumption correct, the supply terminals you need for your new light scheme are those marked N, L, and E in your diagram
The cable list at the bottom of the drawing would be:
#1 light switch
#2 incoming power
#3 to light (a)
#4 to light (b)
If you can confirm the above seems where the wires go, there is a good chance your illustration is correct.
Your multimeter (carefully) connected across your labelled L & N should still show about 240V when all light switches are off!

Urgg not so fast... there's a gremlin in the connection somewhere.

The test of the light switches saw it fail. And it was the 32amp fuse that tripped everytime. I checked the JB for that loose cable and found that the earth was loose from the switch/light cable. I refitted the one you spotted at the bottom terminal, although wasn't clear if it was loose. However the fact that the 32amp fuse tripped I'm going to change the single spot in the ktichen too when I find a lighting loop, or I might just bite the bullet and go for the CU.

So I either need to find another

 

[kreatiff63]

If you inadvertently shorted neutral to earth that can trip the RCD, even with that circuit's MCB off,
That is 'normal behaviour'

when cutting through the cable i probably did that... check my latest post.