I am constructing a 5.44Kg Hobby-weight battle robot and one of the safety rules is that the robot must have a power switch that turns off power to the motors (and weapon).
The robot has three sub-systems; the drive motors (one battery), the weapon (another battery) and some lighting (a small 9 volt battery).
I have read that since all these will be connected to the same receiver it is important to have all the electronics sharing a common ground for everything to work properly.
Now I know that usually it is the "live" wire that is connected to the switch, but I was thinking of hitting two birds with one stone and connecting all the ground wires (rather than the live wires) to the switch. In this way I still turn off power and also have a common ground. In terms of safety (shorts) etc I am not too concerned because I am using XT 60 connectors and have been careful to use only female plugs for the power leads (so no prongs are visible).
It seems to me that it should work and still be safe enough especially since I am not dealing with mains voltage levels here, but on the other hand I don't want to look stupid.
Does this way of connecting to the switch make sense or am I violating some unwritten law? Is this normal practice? Would it effect the circuitry in any way to have the grounds connected together?
I was also thinking of using a switch from a PC power supply; as far as I know this is rated for reasonably high currents. In my case I will have 3 cordless motors, each of which might be drawing up to 5 amps when under load, so say 15 amps in all. Has anyone out there ever used such switches or did you buy high current ones? In that case what should I ask for?