Hello friends, I have been presented with the case of having to automate the lighting of lights in a large underground floor illuminated by about 100 Led tube artifacts with three entrances (two doors and a vehicle ramp). My proposal is to place three motion detectors in each one, associated with a 63 A contactor that cuts the general power supply of luminaires from the main board since currently, by design, these luminaires remain on 24 hours a day. the issue is that the motion detectors would be located about 40 mt. of said board and I have doubts about the possible voltage drop that could affect these sensors if I install the contactor on the board, and what would be the appropriate section of the conductors to use in said circuit. From already thank you very much

You can connect the motion sensors with a three-wire conductor, so that you feed it with the phase and neutral and the third conductor uses it for the return to the general contactor. Having only the load of the contactor, it can be of little caliber, but that supports the tension of feeding, by several tens of meters. You can parallel all the sensor conductors in a box, so that you only get a three-pole conductor to the panel where the contactor is.