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

[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.

 

[Avo Mk8]

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...
View attachment 103294

Sorry I'm not quite understanding the issue.
Yes you can put another L cable into the unoccupied slot of the non-wago Wago!
Similarly for a neutral into a further Wago, and earth etc.
But they will ultimately have to be put in an enclosure, which also encloses all single insulated bits of cable.
(Search "Wago box")
eg WAGOBOX Junction Box 108 x 39 x 44 mm | Toolstation - https://www.toolstation.com/wagobox-junction-box/p92231

 

[kreatiff63]

Sorry I'm not quite understanding the issue.
Yes you can put another L cable into the unoccupied slot of the non-wago Wago!
Similarly for a neutral into a further Wago, and earth etc.
But they will ultimately have to be put in an enclosure, which also encloses all single insulated bits of cable.
(Search "Wago box")
eg WAGOBOX Junction Box 108 x 39 x 44 mm | Toolstation - https://www.toolstation.com/wagobox-junction-box/p92231

I'm not sure whats causing the issue but I'm getting weird behaviour, it may be overloading. The lights stopped working altogether after switching on the kitchen lights and then the outdoor lights (all in the same 4g switch). The 32amp tripped when turning the power back on, but stayed up once i tried the switch again.

I take your point about working tidy as it were, while I'm in 'seeing what works' mode I'm taking shortcuts, cables pinned in place, sheeths etc. Once I know I've got the solution there will be a 'completion' phase.

Back to the issue at hand...

Q: Does the mere fact its a 32amp circuit I've linked into have the type of impact I'm seeing, and if not then is it simply a question of re-wiring the JB to include my new L/N to the switch. Does it mean that I already have an issue on that circuit which I'm simply exaserbating with the additional wiring. I'm using 1.5mm cable for the L/N to the switch.

 

[Avo Mk8]

I'm not sure whats causing the issue but I'm getting weird behaviour, it may be overloading. The lights stopped working altogether after switching on the kitchen lights and then the outdoor lights (all in the same 4g switch). The 32amp tripped when turning the power back on, but stayed up once i tried the switch again.

I take your point about working tidy as it were, while I'm in 'seeing what works' mode I'm taking shortcuts, cables pinned in place, sheeths etc. Once I know I've got the solution there will be a 'completion' phase.

Back to the issue at hand...

Q: Does the mere fact its a 32amp circuit I've linked into have the type of impact I'm seeing, and if not then is it simply a question of re-wiring the JB to include my new L/N to the switch. Does it mean that I already have an issue on that circuit which I'm simply exaserbating with the additional wiring. I'm using 1.5mm cable for the L/N to the switch.

You really should not be connecting lights to a 32A circuit. Apart from not to regs and not safe, the 32A breaker is too big to protect 1.5, even 2,5mm cable. Also if you end up mixing your 32A L with a neutral from a 6A lighting circuit on the other half of the CU, you will be tripping the RCD.
I didn't realise you were pursuing using that 32A circuit. Please don't.
You need to use power from the RCD protected 6A MCB circuit, and only that circuit. Sorry, but that is absolutely essential.

 

[DPG]

I hate to sound negative but I think it's time to accept your are out of depth and need an electrician in for this work. There's no shame in knowing your limits

 

[kreatiff63]

You really should not be connecting lights to a 32A circuit. Apart from not to regs and not safe, the 32A breaker is too big to protect 1.5, even 2,5mm cable. Also if you end up mixing your 32A L with a neutral from a 6A lighting circuit on the other half of the CU, you will be tripping the RCD.
I didn't realise you were pursuing using that 32A circuit. Please don't.
You need to use power from the RCD protected 6A MCB circuit, and only that circuit. Sorry, but that is absolutely essential.

Yes we're thinking alike...

Need to seperate out the facts I think:

• The electrics tripped when I cut the cable I was taking to the switch from the cable that feeds the JB. The 6 & 16s were all off at the CU.
• There was strange behaviour when I turned on other lights in the same switch (not connected), which then didn't work at all.
• The spot light and switch which are fed from the JB turn on and off with the 6amp fuse in the CU switched on/off.
• The lights worked when I connected them up to the wiring config I'm using from GSH Electrics (teacher/practitioner), seemed brighter.

So, unless someone's got some tests I can do to narrow down what the actual issue may be, given all of the above I guess I need to find another source for my supply and also take the single spot off that 32 end loop.

Tests I imagine would be measuring the voltage or amps at each connection in the attic. There are enough cables up there, and we do have lighting in this corner of the bungalow.

I don't thinks its a question anymore of re-wiring that JB.

 

[kreatiff63]

I hate to sound negative but I think it's time to accept your are out of depth and need an electrician in for this work. There's no shame in knowing your limits

I take your point, and agree. Also, I know assumptions are dangerous, I work in Testing software. I thought that as this was feeding spot lights previously and now just the one, that this would be a good one to use. I should have checked it for 'live' after the RCBs were turned off.

But anyway, I take your point and I'm very close to solving this. I'm learning a lot in the process. I wear 'marigolds' .

 

[kreatiff63]

Yes we're thinking alike...

Need to seperate out the facts I think:

• The electrics tripped when I cut the cable I was taking to the switch from the cable that feeds the JB. The 6 & 16s were all off at the CU.
• There was strange behaviour when I turned on other lights in the same switch (not connected), which then didn't work at all.
• The spot light and switch which are fed from the JB turn on and off with the 6amp fuse in the CU switched on/off.
• The lights worked when I connected them up to the wiring config I'm using from GSH Electrics (teacher/practitioner), seemed brighter.

So, unless someone's got some tests I can do to narrow down what the actual issue may be, given all of the above I guess I need to find another source for my supply and also take the single spot off that 32 end loop.

Tests I imagine would be measuring the voltage or amps at each connection in the attic. There are enough cables up there, and we do have lighting in this corner of the bungalow.

I don't thinks its a question anymore of re-wiring that JB.

Here's the layout again of the bungalow.

As you can see the CU is very close to the 4G switch. It will be a more messy job, but once all the powers off in the CU I know I'm connecting to either 16 or 6, probably 6. I would double up in the top with the live wire, and then would I have to connect to the same neutral and earth bars 'number' as the existing cable in the RCB or just ensure I use the same for the new wires? I know that I would have to use the same bar that corresponds to the same section of RCBs.

Diagram below: The faded cream area in the middle represents the boradrd crawl way in the attic. It's spider man after that to get to the lights and down holes for the cables I've used so far. There are spots on that side of the house too, there's a pendant in the master bedroom but thats a long way from where I'm working. Closest are the spots, I guess if I were to go there looking for my L/N then there would have to be something feeding these spots. But thats all under boards... and difficult to get to. I'm liking the CU more now as an option. BUT it would be good to understand exactly what was going on with the JB.

 

[kreatiff63]

You really should not be connecting lights to a 32A circuit. Apart from not to regs and not safe, the 32A breaker is too big to protect 1.5, even 2,5mm cable. Also if you end up mixing your 32A L with a neutral from a 6A lighting circuit on the other half of the CU, you will be tripping the RCD.
I didn't realise you were pursuing using that 32A circuit. Please don't.
You need to use power from the RCD protected 6A MCB circuit, and only that circuit. Sorry, but that is absolutely essential.

I've got what looks like 2.5 and 1.5mm cables running around the edge of the attic. Would it be safe to assume before I cut into the lower one is lighting loop and the top one is for a mains loop? Bungalow was built in the eighties...




And then I have this set up, not my work, close by... the white round thing looks like a junction box. And the white cable goes off to what I think is the conservatory lights.

 

[Avo Mk8]

I've got what looks like 2.5 and 1.5mm cables running around the edge of the attic. Would it be safe to assume before I cut into the lower one is lighting loop and the top one is for a mains loop?

Don't cut into anything before understanding EXACTLY what it is. Preferably don't cut into anything full stop!
Please deal with this in an analytical manner, which you should be capable of if testing s/w professionally.

You need to understand what cable does what and goes where in your existing wiring, map out what needs to be done, and test the validity of your assumptions (eg using a meter) before actually connecting anything.
Don't just try things out to see if they work. Electrics should be done with test equipment and logic.

I'm leaving this, hoping you either get someone in to help/do it, or you spend a lot more time reading up, investigating, testing, using logic and gaining certainty about your existing wiring before trying to connect anything up.

 

[westward10]

I have been following this thread on and off and whilst the forum is happy to help with DIY questions this is getting well beyond what is acceptable and we must consider your safety being a non-electrical person. @Avo Mk8 has given much advice but now quite rightly has drawn a line under it, you need professional help.