I am replacing a dimmer with a smart one. Can I do some clean up in this back box?

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Are those wires contained in steel conduit, is there a brass bush at the back box.
 
If there is no cpc then you will need to use a plastic switch plate and use screw covers
 
Why DO people decorate through a house and THEN start wondering if the electrics are OK and wanting to change things ?
I knew someone who bought an old bungalow, decorated through and laid laminate floor and then decided to renew the central heating system and have some extra wiring done.
 
This backbox in my lounge has an old dimmer switch with a metal plate. Since it has no earth I was recommended to replace it, plus I want to use smart switches all around

Are you sure there is no earth? Looks like it could be a conduit install with the conduit as earth A pic looking up at where the cables enter the box would help.

If there really is no earth, then as well as a plastic switch plate, you should be using nylon plate screws (but lets see if you have an earth first, do you have a multimeter at all?)

Your red on its own is the switch wire to your light, all the other reds are feeds and need be connected together and to the feed terminal of the switch, whether they are all directly in there (likely difficult), blocked together and a flylead, or in the case of the existing, a mix of the two, as there is really no difference.

You could probably dress them all nicely into a 5way wago along with a flylead and keep it to the back against an edge and not loose too much room, don't mumify it in half a roll of tape though, it is neither necessary or desirable
 
A 5 way Wago may not be suitable as that is a double block connector that is taped up.
 
What colour coding would you expect?
This is just my preference and I don't know anyone else who does it BUT
I put a bit of brown( was red) sleeve on the feed, yeah I know it's already brown( red), deal with it!😉😂, likewise with the neutral. If possibly black felt pen marks on the switch feeds and write in back of box what each number is for.. YES I do use as deep a box as possible. Yes I need to get out more
 
Not an expert, but other lights I connected had blue and brown. Plus I'm colorblind. :D And sockets too.

Just not everything red. There's no way to know which cable comes from the bulb and which one doesn't.

Anyway, I managed to connect the smart switch and is working perfect. Now I just need to figure out what to do with the mess or get a chunky spacer in there.
the only 'wrong' colour in there is the yellow. it should be marked red
 
Are you sure there is no earth? Looks like it could be a conduit install with the conduit as earth A pic looking up at where the cables enter the box would help.

If there really is no earth, then as well as a plastic switch plate, you should be using nylon plate screws (but lets see if you have an earth first, do you have a multimeter at all?)

Your red on its own is the switch wire to your light, all the other reds are feeds and need be connected together and to the feed terminal of the switch, whether they are all directly in there (likely difficult), blocked together and a flylead, or in the case of the existing, a mix of the two, as there is really no difference.

You could probably dress them all nicely into a 5way wago along with a flylead and keep it to the back against an edge and not loose too much room, don't mumify it in half a roll of tape though, it is neither necessary or desirable
Here are some extra pics. I do have a multimeter.

I connected the new switch and works perfect. I'm just annoyed with how much it sticks out. I don't even have screws that long to fix it, so atm it's just hanging.

Honestly I would like to understand what are all the cables because it's confusing me a lot. 3 red cables in there, 2+yellow in one end of the block, and 1 red in the other.
 

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cable need joined somewhere, either in the switch or the light. you have them in the switch. your options are either fit a deeper box within the wall, fit a spacer / surrface box, or alter the wiring so the connections are elsewhere

this is a common issue when fitting smart switches & dimmers, there often isn't enough room in the box for anything larger than a basic switch. newer properties are often done with larger boxes for this reason but existing is pretty much what it was at the time
 
cable need joined somewhere, either in the switch or the light. you have them in the switch. your options are either fit a deeper box within the wall, fit a spacer / surrface box, or alter the wiring so the connections are elsewhere

this is a common issue when fitting smart switches & dimmers, there often isn't enough room in the box for anything larger than a basic switch. newer properties are often done with larger boxes for this reason but existing is pretty much what it was at the time
Well, I don't think I'd have a problem if that block wasn't there tbh. I still can't understand why 5 red cables would need to be together.
 
Here are some extra pics. I do have a multimeter.

I connected the new switch and works perfect. I'm just annoyed with how much it sticks out. I don't even have screws that long to fix it, so atm it's just hanging.

Honestly I would like to understand what are all the cables because it's confusing me a lot. 3 red cables in there, 2+yellow in one end of the block, and 1 red in the other.
A few comments on your photo's:-
1) The bottom red cable in the scew terminal doesnt connect to anything else in the box. It could be removed from the terminal, insulated by your preferred means an tucked away in the corner of the box.
2) The terminal above with the yellow and red can be disconnected and the yellow wire discarded, the red wire connected with the other red wire on the switch (yellow and red are joined together).
3) The blue wire in the switch needs re terminating there's way too much bare copper.
4) No sign of any earth conductors.
 
A few comments on your photo's:-
1) The bottom red cable in the scew terminal doesnt connect to anything else in the box. It could be removed from the terminal, insulated by your preferred means an tucked away in the corner of the box.
2) The terminal above with the yellow and red can be disconnected and the yellow wire discarded, the red wire connected with the other red wire on the switch (yellow and red are joined together).
3) The blue wire in the switch needs re terminating there's way too much bare copper.
4) No sign of any earth conductors.
The yellow cables is currently connected with 2 red cables in the block, not just one. I thought of doing what you said, but then I'm left with 2 loose red cables not connected anywhere which I have no clue where they go. And also, the dimmer switch has 2 more red cables. One must be the bulb, but what about the other one (since the yellow is the one acting as live)?
 
The yellow cables is currently connected with 2 red cables in the block, not just one. I thought of doing what you said, but then I'm left with 2 loose red cables not connected anywhere which I have no clue where they go. And also, the dimmer switch has 2 more red cables. One must be the bulb, but what about the other one (since the yellow is the one acting as live)?
So it does after a careful second look. How much room is there in the connectors on the switch? Yellow one out and two reds in? It looks like the blue link wire goes to the same terminal, one the reds could go to the other end?
 
So it does after a careful second look. How much room is there in the connectors on the switch? Yellow one out and two reds in? It looks like the blue link wire goes to the same terminal, one the reds could go to the other end?
Forget the blue. This was just needed for this specific smart switch and I added that one myself.

The old dimmer had yellow+red in one terminal, and another single red (I assume this is the load) in another terminal. I did the same for the smart switch and it works.

Then there is the connector block. 1 terminal has 2 reds+yellow, the other terminal has 1 single red wire.
 
Just because it works doesn't make it safe, looks to be quite a bit of copper showing which could make contact with the un earthed back box. I and many members on here don't mind helping but doesn't seem like you want to listen to the proper way it should be done. If the box was deeper you could make a proper job of it with wagos and fit the smart switch properly. Chasing in might make a bit of damage but if you was to stitch drill first it would make it neater in my experience, may need a bit if filler painting after but would look much better than a spacer that's been made and the switch sticking out much further than needed.
 
We called it slip conduit found it was often broken and not continuous so basically no cpc on circuit
Not worth doing anything to much without getting it tested as you can’t install certain lights and switches without a cpc
Rewire now decorate later not the other way round
It’s not a case of it works so it’s fine
 
We called it slip conduit found it was often broken and not continuous so basically no cpc on circuit
Not worth doing anything to much without getting it tested as you can’t install certain lights and switches without a cpc
Rewire now decorate later not the other way round
It’s not a case of it works so it’s fine

To enhance further on Peterspurs comments....

basic ESSENTIAL rules are......

If in any doubt DON'T change anything!!!
until you have proved which bits are live/neutral/earth and where they are supplied from.

whilst remembering... Dead tests ALWAYS precede live tests!

Testing if something works is the Idjuts method..

The correct and safe way is verifying if something will fail-safe, and disconnect any hazardous voltages quick enough to remove danger to people / property / and livestock!!!
 
Forget the blue. This was just needed for this specific smart switch and I added that one myself.
If this is the case you really do need to hone your electrical skills, way too much exposed copper, close to mounting screws too. You maybe should consider getting a professional in to sort this mess out for you. No consolation if you’ve kept it looking near if you’re 6’ under in a wooden box, you can’t see it. Be under no illusions, this stuff is a killer when it escapes.
 
All folks here have given you excellent advice , and yes I understand you would like to learn how to do it yourself ! ,however if you invest a few quid in a understanding spark who will check earthing, cpc on this circuit and test it all through for you .Then will probably be able to pull a cpc into your backbox via slip conduit and connect this to rest of circuit at a suitable point and fit you a backbox that suits the switch and connections you have .
All who reside in your home have a right to operate that switch SAFELY!.

Spend a little and sleep soundly at night
Regards..
 
I'm sorry chaoscontrol. I'm no expert on electrics though being a property developer I've been working around electricians for 20 plus years and IMO this is way above your ability.
Your colourblind,. You don't have the tools. You don't know if theirs an earth. You don't know where the wires go to.
You should be leaving the switch well alone and calling an expert.
Horses for course's and this is a perfect example
 
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