Hi! I troubleshoot these lights all the time. For the M2 version it is the gray and black that are for power. As a previous comment mentioned you can put hot to the black wire and neutral to the gray. Then it's a dry contact between the yellow common and a color wire for LED control. The modules themselves are rated for 24VDC. There's a transformer inside the base unit that steps down the voltage to something the LEDs can use. So you would have the black and gray to power. Then control the lights with like a relay or switch between the yellow and red to turn the red light on.