Lightswitch with just 2 red wires?

[Jonathandelorean]

I'm looking to swap my single lightswitch over to a dimmer, but after opening it up I see there's just 2 red wires. There is an earth which is connected to a screw in the back box but that's it.

One of the red wires is connected to a terminal labelled "Top" and the other is connected to an unlabelled terminal.

I was expecting to see a neutral wire as the other switches I've changed all have neutrals. The new dimmer has 3 terminals (L1, L2 and Com).

Just wondering which way to wire this up?

 

[AndyPRK]

Use com

And one of the L terminals.

 

[flameport]

I was expecting to see a neutral wire as the other switches I've changed all have neutrals.

Unlikely, switches do not generally have neutral terminals.
Black wires are not necessarily neutral either.

 

[Jonathandelorean]

Unlikely, switches do not generally have neutral terminals.
Black wires are not necessarily neutral either.

Aah ok I had assumed the black wires in the other switches were neutral

 

[Jonathandelorean]

Use com

And one of the L terminals.

That's great, thank you - does it matter which of the red wires I use in which terminal? There's no visual way of differentiating between them.

 

[EFLImpudence]

I shall use my new graphic.

 

[AndyPRK]

No.

You could put Top into Com though.

If the switch works backwards you need to use the other L terminal

 

[EFLImpudence]

That's great, thank you - does it matter which of the red wires I use in which terminal? There's no visual way of differentiating between them.

No, it doesn't matter.

 

[Jonathandelorean]

Thanks for the responses folks!

 

[Sureitsoff?]

No.

You could put Top into Com though.

If the switch works backwards you need to use the other L terminal

or turn the switch upside down!

 

[AndyPRK]

It's a dimmer

 

[securespark]

Aah ok I had assumed the black wires in the other switches were neutral

When you think about that statement, if it were true, the switch would be connecting the live wire directly to the neutral wire every time you closed it.

What would happen then?

 

[Jonathandelorean]

When you think about that statement, if it were true, the switch would be connecting the live wire directly to the neutral wire every time you closed it.

What would happen then?

Ah.. actually that's a good point...

I've always just changed switches on autopilot and never really paused to think much about it. I feel a bit silly now!!!

 

[securespark]

No need. It's a common misunderstanding.