Dimmer switch replacement

[kas3]

Bet no-one can help me on a Sunday!!
Just bought a new dimmer switch for the bedroom- a chrome one: Inside old dimmer switch unit are two red leads twisted together into one terminal and 1 other red wire sheathed in grey flex into other terminal. There are two green earth wires from the red( combined wires) to an earth in the box. Questons:
The new unit has arrow with squigly line, L2 and L1. Which one do I use for the two reds combined?
Where do I put the other red?
Can I unscrew green leads from inside the box and attach them inside the new plate?
Really want to do thi stoday- if possible.Anyone out there who can help KA

 

[RF Lighting]

The two reds twisted together both go into the squiggly line & arrow (common) terminal.

The single red wire goes into L1.

Nothing goes into the L2 terminal (this is only used in a two way setup)

Leave the earths where they are in the backbox, and fit an additional piece of earthwire to link from the earth terminal on the backbox to the earth terminal on the dimmer switch plate.

 

[Steve]

ok. the arrow with squiggly line is the COM - put the 2 wires twisted together here. Put the other wire into L1.

Pull the 2 earth wires out and put them both into the metal plate's earth terminal.

You will need an offcut of earth core, sleeved, to loop this back to the box terminal. Though if the box has one screw lug fixed, i dont believe this is nessecary.

 

[Steve]

@RF

 

[RF Lighting]

@RF

 

[kas3]

Thanks people that is a great help- when you talk about extra piece of earth wire can I get this from existing earth wire i.e cut off a piece and then attach it to back box earth and switch plate earth?
sorry to soung thick where otherwise would I get earth wire -from an old flex?
KA

 

[Steve]

yes, any scrap of old wire will do. A bit of old flex is ideal, since it is already sheathed, and you dont have to buy a 100m roll of sheath for a 2 inch bit!

 

[kas3]

Thanks Crafty
Lost the light now- so rather than attempt this with a torch will wait till next available moment prob Weds morning. I am very impatient but with electrics wanted to get it right. many thanks-KA

 

[mo2]

The two reds twisted together both go into the squiggly line & arrow (common) terminal.

The single red wire goes into L1.

Nothing goes into the L2 terminal (this is only used in a two way setup)

Leave the earths where they are in the backbox, and fit an additional piece of earthwire to link from the earth terminal on the backbox to the earth terminal on the dimmer switch plate.

RF re: the earths does it matter the diameter of the flex becuase I had done exactly what you said, read something from this site(a long time ago which basically said not to) and then removed the earths from the back box and connected them to the switch, then I sheathed some earth core from 2.5mm TandE (I know 1.5 would have sufficed) and sleeved it. I used the sleeved core to connect the switch earth terminal to the backbox terminal. I did this because I thought what I had originally did was wrong - was it?


sorry i'm not hijacking - am i?

 

[Spark123]

The earth core in 2.5mm² twin and earth is nominally 1.5mm². The only reason I prefer to earth to the switch first and then to the back box is the switch earth terminals are generally better quality. I wouldn't advise to use anything less than 1mm² to earth a lighting circuit back box, I prefer the solid copper wire, flex can sometimes have a tendancy not to get a good grip when mixed with a solid copper conductor in the wrong type of terminal.