Sealing conduit penetrations

[PhilIA]

What is the best way to seal conduit penetrations between the wall and a wire trough or electrical box, to prevent moisture getting inside the wall/behind siding? The trough will be installed over board and batten siding, meaning a 3/4" gap between the trough and wall and no easy access for putty.

 

[glandpuck]

All weather exterior caulking and before that try to fill up the spaces from the inside view with insulating expanding foam you squirt into the area. Your biggest goal is to prevent rodents and mice, insects and then water intrusion. If possible, angle the conduit penetration slightly sloping down to drain to the exterior.

 

[timselectric]

Add a piece of batten behind the trough (horizontal) . Caulk the top of the batten before you install the trough. If you line up the top of the batten with the trough. You can also Caulk between them.

 

[Warpspeed]

All of the above ^^^
Plus place a sloping cover over the whole thing so water can never get down there in the first place.

 

[schmism]

expanding foam the bulk of the gap, exterior caulking ontop of the foam as the foam doesn't do well exposed long term.

 

[PhilIA]

Add a piece of batten behind the trough (horizontal) . Caulk the top of the batten before you install the trough. If you line up the top of the batten with the trough. You can also Caulk between them.

That should work great, thanks for the idea.

 

[Warpspeed]

The batten is a good idea, but I would worry about water pooling on top of that batten.
Still think a narrow sloping roof over the whole thing to keep everything reasonably dry might be a more permanent solution.

 

[MarkSolar]

Depending on your local codes, whatever you do may need to be rated for fire. I'd make a piece of flashing to cover the trough and use something fire rated for the penetration. I also use plenum putty inside the conduit to block warm house air from hitting that cold enclosure and condensing moisture.

 

[740GLE]

Was called Nepseal when I worked for the navy, but can be found as Ductseal, it’s like plumbers putty in that it will always stay flexible and keep water out. Can be sourced in 1lbs bricks.