Post
by ericmark »
Sat Apr 23, 2016 9:57 pm
To retain the fuse and have a two way switch means using a grid switch. You need a deep back box but that way you can put any switch you like with the fuse.
However for an outside light we like to be able to switch the neutral as well as line. The idea is should water get in you can simply switch off the light and every thing else in the house will still work.
So better to have a separate switch for the two way system and leave the FCU always switched on except if there is a fault. To the new switch you only need two wires and earth.
So remove the load line wire and put it in a chock block. Then two core and earth brown to load line on FCU and blue to chock block plus earth.
Take this wire to first two way switch and brown and blue go to L1 and L2 (assuming there is a com, if no com then L2 and L3) now used some three core and earth and wire switches like for like so if grey is com with one switch it is also com with second switch.
Note without second switch first switch will do nothing.
Without the two pole switching of the FCU water can cause the neutral to connect to earth, and this can cause the RCD to trip, this is why we give the option to switch both live wires (neutral is considered as live and well as the line wire) but in doors it is unlikely to ever have a neutral earth problem so we only switch the line wire.
I still some times call the line live in error. 40 odd years ago when I started it was called live. If you do not have RCD protection then swapping the FCU to a RCD FCU is easy.
