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Re: Installing Exterior Lighting

From: bobcatm@alamedanet.net
Category: Electrical/Lighting
Remote Name: 24.143.154.241
Date: 26 Feb 2006
Time: 04:23 PM

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Question:I am installing exterior lighting above a side entrance to my house (there is no existing light in this location). I consider it a wet location and the fixture I purchased is rated for wet locations. It will be powered and switched from inside the house (the switch is just inside the door and the wall is currently open so it's easy to run wiring from the inside directly to the the back of the fixture). My question is what is the best type of junction box to use? The light fixture mounting base is approx 6"x5" and 3/4 inches deep. The exterior mounted weather tight boxes won't work as the only ones I've seen are too deep for the fixture to cover. Cutting a 4" hole in the siding/trim for a flush-mounted regular fixture box doesn't seem to make sense due to the the large exposure to the elements and difficulty of framing etc. behind the siding/trim. What I thought would work best is a 4" pancake box (1/2 in deep) mounted on the exterior with a 3/4 or 1" hole drilled thru the siding to allow for the wiring (#12 Romex) to enter into the box directly through the wall. I would seal the penetration with caulk and also possibly use a weather tight Romex-to-box connector if possible. Any advice? Thanks Bob M.

Builders Websource® Answer: Bob, your instincts are good. However, the electrical code specifies that a 4" diameter (1/2" high) pancake box shall only be used at the "end of a run" with a maximum 14/2 Non-Metallic Sheathed cable (Romex or equivalent). For a single lighting fixture, 14/2 should be more than ample for your run to the fixture without excessive voltage drop. Prior to screwing the pancake box to the wall, run a bead of 50-year silicone caulking around the back circumference and wipe off the excess with a rag or a caulking tool, ensuring a good 360-degree weather seal. As you tie in the fixture, wrap the wire nuts with electrical tape to provide a water-tight seal around the electrical connections. Some fixtures come with foam gaskets, but these are not usually deep enough to compensate for large gaps imposed by your siding profile. Depending on your fixture, if you still have gaps between the siding and the fixture, caulk as needed to keep moisture out.

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