Perhaps I didn't communicate clearly. I don't want to completely disable beacon power usage at all times, only disable it when they don't contain any modules.
Well now i get what you wanted but still, im not good with coding (i ususally learn how to code from other mods, modifying parts of their code), so i cant implement it without example, also i tryed to find something like this in existing mods by myself, but i found nothing like this. so sorry i cant implement this
Also as i said higher - there is Power switch to deal with this, just create separate electrecic pole connected through switch to your electricity and set there conditions to turn on, or even whole line of your asseblers to turn on only when there is something on conveyors, not only the beacons.
At least that how people deal with beacons eating too much power before.
So overall i cant implement your idea without exaples sorry, but there is ingame tech to deal with it, and you can try it.