bathroom extractor fan

[scotteng]

I am intending to install a timed extractor fan in a bathroom, coming off the switched lighting circuit. The lighting circuit has no rcd protection. So i am intending to install a rcd spur along with a 3 pole isolaor switch on the outside of the room.
my question.
coming from the light fitting ill have:
Permanent live
Switched live
Neutral
cpc
now how do i wire these to the rcd? when there are two lives?
the extractor is class II, so no earth required, so i take it ill run the earth to the unit and use a connector block to isolate it (for future use).

your help would be greatfull, thankyou

 

[wingcoax]

Can you fit the rcd before the light fitting? If not move the feed to the switch from the light fitting and connect to the output from the rcd and fit a link from light fitting to rcd, and take the perm live from the output of rcd.

 

[ban-all-sheds]

1) Put an RCD FCU onto the lighting loop.

2) Replace the existing light switch with a DP one, switch the live through one pole.

3) From the load side of the FCU take N & permanent live to the fan and the latter to the other pole of the DP switch to give you your switched live.

This will sort out your RCD protection for the new cable and mean that you won't need the 3-pole fan isolator, as turning the FCU off will disconnect all the fan cores.