Copy of PM I sent to TheGreenThing
G'day mate
To seal my light bar I ran clear silicon around the edge of the glass.
I drilled 3 holes in the bottom of the light bar body, lined up with the space behind the reflector. Sorry I don't have any pictures of this, but the easiest way is to line it up with the end cap off. The holes are about 2 inches from each end and 1 in the middle.
I used a 3/16 drill bit.
I still get a little moister inside the bar when driving in heavy rain, but it dries out quickly when the sun comes out.
Hope this helps, if you have any more questions just ask
Andy,