Chas3, I agree. If you are getting power from the reverse light to power up your camera, that power is not adequate for the job. Power should be drawn from a constant source (I used the power to the adjustable rear seat which was a thicker gage wire). The power from the reverse light is good enough to switch a relay, and it should be strong enough to switch your 30 amp relay. What does matter is that the ground to pin 86 is a good one. I ran a separate ground instead of using the reverse ground.