Unexpected coloured wires and two going into L1 on dimmer switch

[Benjic]

I’m trying to replace my first dimmer light switch and have popped open the old one to see how it’s wired. The strange thing is the colours don’t seem to match what any UK wiring colour guides I can find state they should be.

It looks to me like I have a light brown wire going into the squiggly line with the arrow connector and a darker brown wire and black wire going into L1.

Is this colouring normal (brown, brown and black)? Seems like a bad idea to have two similarly coloured wires in anything involving electricity but that’s just my layman opinion.

Assuming this is expected, is it correct to have two wires going to L1? If this is wrong I’d like to correct it when installing the new switch.

(Attached photos for clarity)

 

[flameport]

If the existing one works, it's correct.
New one connects in the same way.

If it has a metal plate, an earth wire is required to the terminal on the metal plate. Existing switch is missing that.

 

[Benjic]

Great, thanks!

Good point about the metal plate. The new switch has a metal outer cover but, most importantly, I notice it has an earth connector so I guess I got the wrong kind of dimmer?

 

[terryplumb]

Great, thanks!

Good point about the metal plate. The new switch has a metal outer cover but, most importantly, I notice it has an earth connector so I guess I got the wrong kind of dimmer?

Eh ?? If it has an earth terminal it must be earthed. Are there no earth conductors present in the mounting box ?

 

[Benjic]

No, there’s no earth conductors I can see. The currently installed switch has no need for one it seems.

 

[terryplumb]

Show us pics of wiring within the mounting box.
Your old switch has an earth terminal,and as stated by flameport does require earthing.
If there really aren't any earth conductors present ,you would need to fit a plastic switch ,and the rest of the accessories ,light fittings,switches etc need to be inspected . You may have some potentially very dangerous items.

 

[Benjic]

I’m really confused now. I don’t see an earth terminal on my old switch and there’s only those three wires (light brown, dark brown and black).

I’ll just give up and call an electrician I guess

 

[markyd1]

Yes

 

[JohnW2]

I’m really confused now. I don’t see an earth terminal on my old switch and there’s only those three wires (light brown, dark brown and black).

Are both your photos of the old switch. If so, they do show an earth terminal ...

Kind Regards, John

 

[CBW]

Tbf existing switch appears to be plastic and backbox is plastic plasterboard type. I thought Earthing arrangements were still needed for the cable?

 

[JohnW2]

Tbf existing switch appears to be plastic ...

What we can see certainly looks like plastic, but that earth terminal makes me wonder what's on the other side. It could be there simply as a 'parking place for 'un-needed' earth wires )on an 'all plastic' switch), but that's not something I've commonly seen in switches.

and backbox is plastic plasterboard type.

That is certainly true

I thought Earthing arrangements were still needed for the cable?

I'm not sure what you mean by "for the cable" but the regs certainly so require that a CPC ('earth') be run to 'every point and accessory' in a circuit, even if 'it is not needed' (I guess in case it is 'needed' in the future)), and the pics we've seen so far show no evidence that such is the case.

Kind Regards, John

 

[Jon c]

Judging by the first pic it looks like a mess of wiring has been shoved in behind the box, obviously the wrong way to do it. That is probably where the CPCs will be. Needs an electrician to sort it out really, dealing with busy light switch wiring can be difficult without experience.

 

[terryplumb]

That switch is a low profile ,clip on metal front. The switch plate is metal with a plastic edging,and clearly has an earth terminal as shown by Johnw2 above.
It 100% must be earthed.

 

[Benjic]

Okay, so that earth connector (bottom left on attached photo) seems to go nowhere (or is the fact the clip on metal front touches the switch plate enough to do the earthing?).

Does this mean the existing switch is wired dangerously then?

 

[CBW]

I'm not sure what you mean by "for the cable" but the regs certainly so require that a CPC ('earth') be run to 'every point and accessory' in a circuit, even if 'it is not needed' (I guess in case it is 'needed' in the future)), and the pics we've seen so far show no evidence that such is the case.

I was told, that even though class 2 products don’t require and Earth/cpc, that it needs to be there should anyone accidentally cut through the live and or neutral wires.