I have a situation (USA) where there's no practical alternative except run some low voltage wiring in the same conduit as 120/240V power.
The good news is, my situation calls for using entirely mains-type cable (THWN-2, 12/3 NM, etc.) for the low voltage stuff, and all the hardware will be enclosed in junction boxes listed for mains electrical service.
It's for relay circuits; the relay coil is tapped for 24V or 240V (I'm using the 24V tap) and the 120-24V transformer is obviously insulated for 120V (though it is not made to have 120V across its secondary).
What do I need to do in order for this to be allowable and safe?