I have plenty of home electrical wiring experience with romex and BX cable, as well as with the cable clamp connectors used with indoor metal electrical boxes (both NM clamp/connectors and connectors for BX).

What I don't have experience with is using conduit.

I'm planning to install a GFCI outlet (and another plain duplex outlet) in a surface-mount electrical box with a weatherproof cover, on the wall of a partially-open shed adjacent to my house. The area is subject to dampness, but not generally to direct water (although condensation could occur, and it's possible that high winds during a rainstorm could wet the box.

I'd like to power it from an NM cable directly run through the exterior basement wall to the box (on the other side of that wall). I haven't chosen the actual mounting location, so I guess that it is possible that I might need a short run of outdoor-rated UF-B cable.

Here is the weatherproof box that I'm planning to use:



It has three holes in it, but they're not knockouts, rather they're 1/2" threaded holes designed for use with some kind of conduit fitting. I will cap off two of them, and use the third to bring power into the box.

But, never having worked with such fittings, I'm unsure of what the proper fitting to use with the UF-B (or plan NM cable, if I end up going directly through the wall and into the box through the hole at the back of the box).

I have seen 'waterproof' connectors at Home Depot, but the package descriptions seem to indicate that they're intended for use with rigid conduit.

What is the recommended way to bring NM cable into such a box? Specific part number from Home Depot would be a big help.

Thanks...

Get one of those whips pre wired at home depot that have the water proof connectors. Run it inside then switch to nm

I believe it will thread into that box. The use npt.

Whip

You can also do it with the PVC conduit. They have coupling fitting with a thread

That looks like it would do the job.

Can I just run it through the exterior sheathing and into the basement?

If that's the case use a nipple to connect that box to a junction box on the Inside of the house, you can run the nm into there.there are nuts and plastic protector bushings

The whip is more for something like an ac to a outdoor power switch

hmm I have always just stuck a male connector in the back, used a holesaw to punch through the sheething and screwed the box on, then caulked around the male connector and inside it once the wire is in.

OK, thanks for the info, much appreciated...

This right here.
ETA, the plugs that screw into the other hubs to seal them need a shot of silicone on the threads or they won't seal properly.

You can use NM to feed the box since the connector is inside.

No reason to make it more complicated.

Call the AHJ and make sure they will accept it.

They might want a section of UF to feed the box since the exposed box is a wet location.

What kind of connector, though?

An NM connector? Or some kind of conduit connector?

The conduit nipple idea sounds straightforward and cheap enough but a connector might be even cheaper - it's just that I don't have the experience to know what kinds of connectors might do the trick.

1/2 pvc male conduit

is what I have used.


EDIT: HMMM the new arfcom messes up granger links...
further edit... link work is Mozilla... get a messed up ad redirect in IE
https://www.grainger.com/product/CANTEX-Male-Adapter-4FYC3

Ah, that looks like it would be just right, thanks...

Both of these are good advice.

Be sure to drill a drain hole in the bottom of the box, "provision for draining." 1/4" hole is plenty.
No need for UF wire if the NM doesn't leave the box.

An exterior box is a wet location in most cases.

The paper filler in the NM rots and wicks moisture.

The cable is going to leave the box by definition.

The OP didn't mention the wall material but if it's block I like using rigid pipe. The advantage is you do not use a male adapter (connector) so the hole doesn't need to be larger than the pipe itself, for 1/2" pipe that's roughly 7/8" and it is easy to seal.
For 8" block you can use a 12" nipple which will thread directly into the back KO on the box then inside of the basement use a rigid coupling with a flex connector and flex over to a box mounted somewhere easy to access.

1/2" UF connector @ Home Depot, Lowes etc.

Run romex and use a typical romex connector.  You will have to drill/chip out a bit more of the hole to accommodate the connector coming out of the back of the box, but the holes itself only needs to be 1/2".  Seal it with some silicone and you are good to go.

I have done (literally) hundreds of these.  I've never failed an inspection.  Yes, some people can argue that the inside of the box is a wet location, but it will never fail.  Some people are just being paranoid.

OP I just did this.

I used the single gang grey plastic outdoor box with the single 3/4" grey PVC female fitting molded into it.

Drilled a 1/2" hole in the back as well as through my house at a stud in the attic that was on the outside wall.

Ran romex through

Screwed single gang box into the wall and sealed with caulk

Installed weatherproof 'in use' clear cover and GFCI outlet in box.

Done.

It is one of those AHJ arguments that is not worth having.

Asking a polite question of the AHJ will usually get an answer.

A simple "What do you see for feeding an exterior box from inside a house?" will likely produce at least some comment.

Over the years I did enough of the PE sealed drawing thing if it was worth the trouble.
A license and a seal goes a long way if you really need to push.

Are you using Weather Resistant GFCI's?

Even before I started using those, I have GFCI's at customers houses for 20 years and rarely an issue.