Should an exterior surface-mounted outlet box on wood lap siding be flashed?

Question

I'm adding an outlet box to the wall over my deck by drilling a penetration through the wall just to feed the cable through. Will air seal with expanding foam and caulk and feed into a surface mounted exterior weather proof box and outlet cover through the backside of the box.

In addition to caulking the perimeter of the box before screwing it into the siding was thinking of installing a small section of L flashing tucked up into the lap of siding above the box to help minimize water dripping directly onto the top of the box and relying solely on the caulk to seal, but almost every video or how to I see of these retrofit installs has the box just mounted directly to the exterior. (I was thinking of it like the flashing detail on top of a window install around the siding)

Am I being overly cautious or would this somehow affect the rest of the water barrier system of the siding?

Answer 1

I don't think using a flashing will hurt anything; but I also don't think it is necessary if you properly install a weatherproof box.

You should consider potential cut/scrape hazard scenario as people (e.g.you) will be plugging things in and out, placing body parts near sharp sheet metal flashing. Also, make sure it will not interfere with the weatherproof box cover doors/flaps and/or any in-use covers you might use.

Also, I think that technically you need to feed the wire into the back of the box through a short conduit with a bushing (bushing to protect wire from damage where it enters the conduit), because of the wood siding...