2 gang 2way light switch old to new help please

[Scearsy]

how do I change the old to the new please

 

[pete01]

Old/new

L1/common

L2/ 1 way

L3/2 way

 

[pete01]

And the new switch needs to be earthed.

 

[CountryFan]

And the new switch needs to be earthed.

As would the back box?

 

[pete01]

As would the back box?

I presume the earth wires already go to the back box, I would leave them there and take a fly lead to the switch, others choose to move them to the switch and leave the back box unearthed.

 

[Jurassicspark]

As would the back box?

Lets say someone changed the switch to a metal plate version and before it was plastic then the metal plate must be earthed. The discussion is then how? What would you do?

Some will say that the CPC should be left in the box terminal and a flylead connected between this and the switch.

Others will say move the CPC to the switch plate. My issue with this issue is that the earth connection to the back box is now fortuitous, and will be lost when the accessory fixing screws are removed or loosened.

Some may disagree.

If there is a fixed lug then earthing the back box isn’t necessary providing the earth path is continuous from the screws but earthing the switch is of course vital.

Are backboxes classed as an exposed conductive part (does anyone know and can clarify why?) and must be earthed, the fixed lugs of a back box are an earth connection if the switch itself is earthed then continuous through the lugs/screw and so an earth tail is not however it is good practice. If there is no fixed lug then an earth connection is required.

 

[Jurassicspark]

, others choose to move them to the switch and leave the back box unearthed.

But have they acknowledged the fact that at least one lug is fixed considering if it’s a metal back box?

 

[pete01]

A back box isnt exposed so I'd say no.

 

[Jurassicspark]

A back box isnt exposed so I'd say no.

What about the faceplate screws?

And if you consider the screws to be exposed would you earth the back box considering it’s a plastic un earthed switch?

 

[pete01]

What about the faceplate screws?

They are screwed onto the earthed metal switch face?

And if you consider the screws to be exposed would you earth the back box considering it’s a plastic un earthed switch?

I would yes

 

[Jurassicspark]

I would yes

You can’t say you haven’t seen a plastic faceplate with a metal back box which hasn’t been earthed?

 

[pete01]

I wasn’t challenging you mate was just curious as some people say the opposite.

I know mate

 

[pete01]

You can’t say you haven’t seen a plastic faceplate with a metal back box which hasn’t been earthed?

I have but the older boxes had plastic lugs....didn't they?

 

[bernardgreen]

 

[morqthana]

Scearsy - pay attention to bernardgreen's image - in your old switch the right hand one (viewed from the back) is upside down

Your new one isn't - don't get the L1/L2/L3 from two switches mixed up...