Lightswitch - No COM?

[anahavana]

Hi there,

I'm changing my first light switch plate. Momentous occasion.

I'm changing a 1 gang plastic plate to a metal plate.

I removed the plastic plate and only two wires and holes in the back of the plate:
- black going into the top hole marked as TOP
- red into bottom hole which has no marking.

Am I right in thinking the hole marked TOP is essentially the COM hole which is on my new plate? And should I go ahead and put the black wire in there and the red wire in the L1 hole as shown on the new plate?

Also, the earth wire is screwed in to the actual box. I know I need to earth the switch plate too now as it's metal. Do I unscrew and strip back the current earth wire and add some more copper wire to this, screw back in and screw the remaining wire into the switch plate?

Thanks in advance.

 

[PrenticeBoyofDerry]

There are no hard set rules to which colours do which on the light switch.

Firstly you require an earth on metallic fittings, best practice is to connect both to switch plate and backbox, so short length of earth cable will be required.

Generally red to com and black to L1

Some switches are marked differently though you may have L (treat this as com)
and L1 (the same)

It is also advisable to prove there is a path to earth, a visual of the cable is not enough, you require to test using a suitable continuity meter

 

[333rocky333]

"Top" refers to the way the switch goes up rather than the hole

It is very rare to have no markings near the terminals, but as above if there is only 2 holes then its not a problem.
The earth is however important to your new metal switch.