Discuss Lights - Why is the my supply switch controlling my new one? in the DIY Electrical Advice area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

Status
Not open for further replies.
Reaction score
8
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

Lights - Why is the my supply switch controlling my new one? 1667137610864 - EletriciansForums.net
 
TL;DR
lights, supply, switch
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
 
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

    Lights - Why is the my supply switch controlling my new one? 1667145223891 - EletriciansForums.net
 
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
 
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
 
Last edited:
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
 
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?
 
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.
 
"...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.
 
  • Like
Reactions: 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
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.
 
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?

Lights - Why is the my supply switch controlling my new one? 1667215545417 - EletriciansForums.net
 
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
 
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.
Lights - Why is the my supply switch controlling my new one? {filename} | ElectriciansForums.net


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
Lights - Why is the my supply switch controlling my new one? 1667233669647 - EletriciansForums.net
 
Last edited:
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!
 
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.
 
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...

Lights - Why is the my supply switch controlling my new one? 1667235893491 - EletriciansForums.net
 
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
Lights - Why is the my supply switch controlling my new one? 1667310967395 - EletriciansForums.net
 
Last edited:
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:
 
Last edited:
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:

I've got this, is this one?

Lights - Why is the my supply switch controlling my new one? 1667315994659 - EletriciansForums.net
 
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:
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?

Lights - Why is the my supply switch controlling my new one? 1667321743109 - EletriciansForums.net
 
Status
Not open for further replies.

Reply to Lights - Why is the my supply switch controlling my new one? in the DIY Electrical Advice area at ElectriciansForums.net

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc
This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock