I'm about to try and create a light bar tomorrow using one of Halfords finest commercial vehicle roofbars cut off to a dead length across the roof and then drilled to provide a mounting point for 6 lights - 4 pencil beam spots and 2 fog floods.
I'm trying to decide where to mount things - I'm already planning twin power feeds for the lights themselves with 3 lamps driven off each feed simply to avoid having to run ludicrously thick cable around the car, but I'm trying to decide where to run the power through the body.
The 2 options that occur is to drill straight through the centerline of the roof and use the space above the cabin light to house the relays for each circuit or to mount the relays on the bar itself and run the power lines through one side of the roof, probably the drivers side.
I suspect that the centerline option will make for a nicer fix when I come to get rid of the car, but suggestions are sought as they say.
The lamps are a bunch of 4" Cibie H1 units and 2 Ring square spots - total of 310W of lighting up there.
P.