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need advice for outdoor mounting of boxes

Posted by njitgrad (My Page) on
Fri, Jun 7, 13 at 14:12

I need to mount the outdoor box (pictured below) onto my vinyl siding (pictured below) for an electrical line.

I also need to mount the PVC pull elbow (pictured below sticking out of the mulch) for my sprinkler system wiring into my cinderblock wall which will connect in my basement.

I need to know from start to finish what I need to do for each of the two tasks. I can't find this information anywhere.

For the electrical box I will be drilling through my sill plate and right through the siding. Do I need to enlarge the hole from the outside? After running the wire through the hole in the wall and mounting the box, what do I use to seal the hole in the vinyl siding outside and how do I go about doing this?

For the PVC elbow, I need to rent a hammer drill to make a hole large enough (from the basement outwards) for the PVC to fit in. What should I use to weatherseal it from the outside and inside? I plan on putting an identical elbow inside the basement on the other side of the hole.

For the electrical box, I'm going to have a tough time finding a spot for the junction box in my basement near my sill plate. It doesn't have to be mounted right over the hole right? If not, what should I use to fill the hole in the sill plate after running the UF wire through to a suitable location for the indoor junction box?

Follow-Up Postings:

RE: need advice for outdoor mounting of boxes

I just bought a product called duct seal. Its a moldable putty for sealing conduits. How do I effectively apply it?

RE: need advice for outdoor mounting of boxes

No takers?

RE: need advice for outdoor mounting of boxes

Unless I'm missing something, I would make both holes through the sill, and the first cut I would make (after measuring about 5 times) would be with a knife through the siding from the outside, to make a round hole roughly the diameter of the pvc and to expose something firm and unshreddable in which to start a drill bit. (no need for a hammer drill here if the sill is wood.)

The box doesn't have to go right over the hole.

Work the duct seal in your hands to warm it up and make it softer, then apply it like modeling clay to seal the edges of the opening after the PVC is in place.

RE: need advice for outdoor mounting of boxes

Well, the thing is that I want to minimize the amount of PVC sticking out of and/or traversing the wall.

For the sprinkler wire, since it comes up from the ground, the shorter the height traveled up the wall, the better. Otherwise I have to run a conduit over the siding and that would be ugly. That is why I am considering drilling through the cinder block wall.

For the electrical outet, I really want to mount the box flush with the wall, right over the hole. I don't want any elbows or anything of the sort coming out of the hole and then eventually connecting to an outlet. I can't picture it any other way, unless someone can suggestion an alternative.

RE: need advice for outdoor mounting of boxes

Actually this example I found isn't too bad (the concept behind it, not the actually hardware used).

RE: need advice for outdoor mounting of boxes

I just came across a good set of instructions (see below), however the author did not seem concerned with filling the hole and only sealed the perimeter of the box with silicone. I would imagine that the hole should at least be filled from the inside, otherwise small insects could get in underneath the siding.

Here is a link that might be useful: Outdoor Electrical Outlet

RE: need advice for outdoor mounting of boxes


I make no comments about code. But in that link you supplied, that is very close to what I did. Only difference is I used a 2-gang box (same brand, same plastic cover box), and installed a timer in one side and then a GFCI plug on the other side (better safe than sorry). I also installed strain relief in the back of the box, incase someone in the crawlspace decides to yank on the wire for whatever reason. Just a simple romex clamp.

Great for Christmas lights.

I siliconed the heck out of the top and sides of the box as well as a smattering on the back of the box before putting in the screws during installation and was good to go.

My house is stucco though, so insect intrusion is not really a concern.

Good luck to you.

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