(this is the Electrical lead): By running the pwm signal wires next to large motor wires that could potentially have upwards of 40 amps through them, you risk electromagnetic interference across the pwm. For this reason we like to run our pwm cables as far away from our power cables as possible, and where they have to come near each other, we cross them at a 90 degree angle. This prevents the magnetic fields on the power cables from interfering with pwm communication.
