Here is a little tip I picked a few years ago and has saved me some work in the past....when you put a tubular conduit in any where, when you thread the wires through attach a piece of string to the end when pulled through leave about 6-8 inches of string either end so if you have something you want to add at a later date (sensors, lights etc) then you can use the string to pull any more wires through(dont forget to attach another piece of string)..... always keep it there in case you need it again
here I have done it for my rad fan feed and switch.
