if you want to power the camera and monitor in reverse only, you would take power from the back-up light, splicing into the wire that supplies the light. you would also need to send this power to the monitor. with a wire going thru the pipe to turn on the monitor at the same time. there is also a cable going from the camera to the monitor to supply the signal. so, there are two different wires in the pvc pipe, one for 12 vdc power, the other for signal. I chose to be able to manually turn on the camera anytime. then I took power from the cab fuse block, mounted the switch shown in the picture. you would still have the same number of wires in the pipe. except now the power goes to camera from the cab instead of from the back up light....there are fused leads available today that make picking up power from the fuse block just a matter of sliding a clip onto the fuse block