Wire through roof

hikingff77

Adventurer
Can someone tell me their experience with the best way to run a wire through the roof for a beacon/emergency light?

Right now I have my volunteer firefighter blue light running through the door and all it does is make a point for the water to come through when it rains.

I want to drill a hole under the light position, plan on using a wire grommet and then silicone/puddy the hole up.

Thanks.
 

seanz0rz

Adventurer
ive done several antenna mounts on cars.

as im not familar with the specifics of your light (whether it has a flat bottom, or just a rim that contacts the roof, etc) ill explain both.

for just a rim'd bottom light: drill the smallest possible hole for the wire. use a rubber grommit to protect the wire from the metal edge. using black silicone (or clear, either works fine, i find black looks better if it manages to squeeze out) put a very generious amount around the grommit and wire, then apply a small, smooth bead around the rim of the light, pull the wire tight and seat the light. if you have any screws, make sure you apply a liberal amount of silicone around the holes as well.

for one with a flat bottom, same as above, though you probably will not have clearance for the rubber grommet. just make sure to apply plenty of silicone, if it squeezes out, try to clean it up as best as possible, and you can trim the rest later with a razor knife.

if the light is not mounted to the roof, just use the grommet and plenty of silicone around the wire. use the smallest possible grommet you can! if you need to, you can build up the wire with electrical tape (following proper application of electrical tape - tight wraps until the last 1-1.5 inch)
 

spencyg

This Space For Rent
I learned a long time ago that gluing a wire in will eventually lead to problems, either with water intrusion, corrosion, or just the extreme inconvenience of not being able to remove it for maintenance. I'd recommend one of two solutions. The best solution is IP67 connectors. They are waterproof and can be disconnected as required.

www.binder-usa.com makes some nice stuff.

The other option which doesn't involve glue or sealant directly on the wire but is also a bit more permanent is a gland-type wire bulkhead connector. Typically they are referred to as a liquidtight strain relief.

http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1941623&PMT4NO=62522979

They can be purchased for many different cable types. MSC has tons of different styles.

Both the IP67 connector and the Liquidtight strain relief require sealing into the hole you make in the roof to accomodate the connector, but the wire itself can either be unplugged (IP67) or pulled out (strain relief).

Good Luck.

Spence
 

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