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Have just replaced an old single plastic light switch with stainless steel version (also added an earth wie to connect switch to metal back box). Original had Red wire into Com, Yellow in L1 and Red in L2 - all single wires. New switch was identical setup and I marked cables before removing original, so 100% same setup, BUT the light comes on when switch set to off & vice-versa.

I could spin the whole switch round which I presume is safe (or is it feasible to swap the L1 & L2 cables?), but just like to understand why this has happened when nothing is different apart from the addition of an Earth wire. I understand the com/L1 connections, but not sure what purpose the yellow in L2 has on this switch - I did 2 other rooms & they had 2 and 3 reds respectively in Com and just a single red which I put in L1.

Thanks
 

littlespark

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Arms
Esteemed
A 2 way switch simply switches the C common between L1 and L2.
It just depends on the manufacturer if L1 is switch in “on” position and L2 is “off” or vice versa.

Swap L1 and L2 over or turn the switch upside down.
 
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  • #4
Thanks to all for quick reply. Makes sense when you point out that different manufacturers may vary the on/off positions (especially when old switch is 20+ years). I guess it only became an issue with this switch as it used both 'L' ports. Will probably switch L1/L2 now that I know it's safe rather than turn switch which may stretch the wires. Cheers..!!
 
Have just replaced an old single plastic light switch with stainless steel version (also added an earth wie to connect switch to metal back box). Original had Red wire into Com, Yellow in L1 and Red in L2 - all single wires. New switch was identical setup and I marked cables before removing original, so 100% same setup, BUT the light comes on when switch set to off & vice-versa.

I could spin the whole switch round which I presume is safe (or is it feasible to swap the L1 & L2 cables?), but just like to understand why this has happened when nothing is different apart from the addition of an Earth wire. I understand the com/L1 connections, but not sure what purpose the yellow in L2 has on this switch - I did 2 other rooms & they had 2 and 3 reds respectively in Com and just a single red which I put in L1.

Thanks
May have had a redundant pull switch in the past which is hidden or on connector blocks hidden...maybe.

Reverse L1/L2 would be my shout.
 
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  • #8
May have had a redundant pull switch in the past which is hidden or on connector blocks hidden...maybe.

Reverse L1/L2 would be my shout.
That's the bit I don't understand - this is a small bedroom with the light switch just inside the door. Apart from sockets, there were no other switches, controls etc in this room when we moved into the house, so not sure what it would have switched to when light was turned off. It hasn't caused any problems in the 20yrs we've lived here, so guess it has been terminated correctly...!
 
It is possible there was a pull switch at one time to control the light from the bed.
 

Strima

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Arms
Esteemed
As others have mentioned there was probably a switch near the bed which has since been removed. Either swap L1 & L2 or just flip it over.
 
That's the bit I don't understand - this is a small bedroom with the light switch just inside the door. Apart from sockets, there were no other switches, controls etc in this room when we moved into the house, so not sure what it would have switched to when light was turned off. It hasn't caused any problems in the 20yrs we've lived here, so guess it has been terminated correctly...!
A lot of older houses used to have a pull switch that hung at the centre of the bed headboard. May have been removed connector blocked and plastered into the ceiling.
 

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