Dimmer switch confusion

EdTheNed · Feb 9, 2022

First off, I'm clearly not an electrician and I'm sure the answer is simple, but I didn't want to go messing with the wires without being sure.

I wanted to change to a dimmer switch, so I've got some dimmable LED bulbs and a Varilight V Pro dimmer switch.

When I took the old switch out of the wall, I saw that it's only the live wires attached to the switch itself.

[ElectriciansForums.net] Dimmer switch confusion

The dimmer switch has a metal faceplate, so I don't want to mess anything up with the earth wire (or anything else for that matter).

Instructions shown here...

The manual says to "copy the wiring configuration", so leave everything as-is, putting the three live wires (from the top of the old switch) in the L1 terminal and the other one (from the bottom of the old switch) in the C terminal.

One thing that confuses me is the earth not being attached to the dimmer's earth terminal on the back of the faceplate - surely this is needed for a metal switch. Also, do the neutral wires need to be moved, or can they stay where they are i.e. not connected to the actual switch?

And the diagram shows a wire called "N" (presumably neutral) going in to "L1" (which I would have thought was "live"). The "L" wire (live?) is going in to the "C" terminal. The "C" terminal is actually marked with a wavy line and a diagonal arrow (meaning, I think, variable AC power).

I'm not even sure how I'm going to stuff four wires into a single terminal, but if that's what I'm supposed to do, I'll give it a go.

Any help very much appreciated.

loz2754 · Feb 9, 2022

The N or neutral wire shown in the diagram is not connected to the switch at all, but to the load (which is your light).
You're correct the metal faceplate will need an extra link wire fitting from the the existing earth wires to the faceplate earth terminal.
The neutral wires in the connector block stay as they are with no connection to the switch.
As fitting 3 wires into a tiny dimmer terminal is going to be problematic, you should connect the 3 wires into a connector block and add a link wire from this to the common terminal of the dimmer.

EdTheNed · Feb 9, 2022

loz2754 said:
The N or neutral wire shown in the diagram is not connected to the switch at all, but to the load (which is your light).
You're correct the metal faceplate will need an extra link wire fitting from the the existing earth wires to the faceplate earth terminal.
The neutral wires in the connector block stay as they are with no connection to the switch.
As fitting 3 wires into a tiny dimmer terminal is going to be problematic, you should connect the 3 wires into a connector block and add a link wire from this to the common terminal of the dimmer.

Thanks so much - I managed to get the three live wires in the one terminal so happy days. Honestly, I thought nobody had replied so I just went ahead, didn't bother with the earth, works fine, but OBVIOUSLY THIS IS NOT RECOMMENDED I AM DICING WITH DEATH! The other live went into the wavy line/diagonal arrow terminal no bother and my new dimmer light works perfectly.

I will sort out the earth wire before it kills someone, promise.

Just wanted to say how much I appreciate someone who knows what they're talking about (loz2754) taking the time to stop idiots like me zapping themselves with lethal amperages. It's not the first time I've tried to save money by asking online on this excellent forum, and I'm still alive with working lights. I'm still an idiot, though.

Hats off to you loz2754 my friend. I am eternally in your debt!

LewisM · Feb 9, 2022

I'd recommend fitting a fly lead for the permanent to the switch and putting the three lives and fly lead into a wago as I don't think three wires into one of those terminals will make a secure connection long term

littlespark · Feb 10, 2022

Use a fly lead for the earth as well. Getting all those into the terminal will be easy enough, but the pressure of pressing against the switch can loosen it.