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We'll be laying out several new driveway slabs for our daughters to park on when commuting to college, and need a couple of NEMA 14-50 outlets near those slabs as they both want Nissan Leafs. We will be laying conduit under the 19' of driveway, and popping it up beside the new slabs (approximately 24' from the house). I was going to purchase a couple of weatherproof outdoor boxes from Amazon that look like this:

Outdoor NEMA 14-50 outlet

Obviously, I can't just connect the wires and lay this box on the ground. I assumed I could search Amazon or google for "outdoor electric box post" and find a bunch of affordable metal posts with standard mounting brackets for boxes like the one above, but I just keep seeing garden light posts. Amazon did show this, but it's designed for standard 120 outlets and I'm unclear how/if I could mount the box above:

enter image description here

I've searched for installation videos and articles for outdoor outlets, but gave up after over 20 in a row showed them being installed against the side of a house.

I could, of course, cement a 2x4 into the ground to attach the box to, but besides being ugly I feel like nailing a high voltage electrical device to a flammable stick may be a bad idea. I suspect code would agree with that.

What is the appropriate way to 'mount' a box like the one I show above so that it is held securely away from the ground? What, specifically is that type of post called? Or is the box above the wrong product for my application?

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    "I feel like nailing a high voltage electrical device to a flammable stick may be a bad idea" There's nothing inherently wrong with it. That description fits many US residential installations (boxes nailed to wooden studs or joists) and code is fine with that.
    – nobody
    Commented Jun 18, 2020 at 20:05
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    Mount it to anything strong and stable. More importantly, protect the wiring all the way into the box with appropriate, rated conduit.
    – isherwood
    Commented Jun 18, 2020 at 20:06
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    We use a telephone pole. It’s a much larger stick, pressure-treated in flammable creosote. What could possibly go wrong?
    – Harper - Reinstate Monica
    Commented Jun 19, 2020 at 0:09
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    Another thought is that you are putting an immovable thing near a moving thing, being the post and the car. There is potential for a bump (not picking on the driver's skills, but you know its possible) so consider what would happen if you used a thinner mounting post, it gets knocked over, and repair. Perhaps check out examples of mailbox mounting posts that are designed to break-away, with a thin 2x2" post at ground level and a more-solid post higher up. Also put the cable in flexible protection, not steel pipe. Comment cos not answering main question.
    – Criggie
    Commented Jun 19, 2020 at 21:19
  • A 2x4 is a little on the thin side. RV parks and campgrounds usually use a 4x4 instead.
    – Mark
    Commented Jun 19, 2020 at 21:20

2 Answers 2

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My 240v stuff is all nailed to a flammable box, which I live in. - A 4"x4" should be fine. Use any visually acceptable piece of painted wood, vinyl, or painted metal; you don't need a bespoke "240v box post". Use a large radius bend between the horizontal underground run and the vertical, attach the vertical conduit to the post, and pour concrete around both post and conduit. This will constitute a permanent installation.

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  • I was going tosay a 6" x 6" but I guess a 4" x4" would do it if the holes in the box are close enough together.+
    – JACK
    Commented Jun 18, 2020 at 20:12
  • A 4x4 will be fine. Paint it to match the box, or the house, or dark green if it's in front of shrubs. Consider making it a few inches taller than the box (code may specify a minimum height for the box, btw), and put an ornamental top on it.
    – TomG
    Commented Jun 19, 2020 at 0:31
  • Get the boxes before you set the posts, you might find a 4x6 or 6x6 is a lot easier for the mounting pattern on the back of the box.
    – NoSparksPlease
    Commented Jun 19, 2020 at 4:03
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    @TomG disguising it Ruth paint, while aesthetically pleasing, may make this post hard to see when reversing into a drive, especially at night. I’d suggest a light or some reflective material on the top.
    – Tim
    Commented Jun 19, 2020 at 8:39
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    Great suggestions. I think I'm going to do a 4x4 with a white sleeve to match our deck posts. Then place a post-cap-light on top so it's easy to plug in at night.
    – Nicholas
    Commented Jun 19, 2020 at 13:39
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They make a special box for RV stands. It has that NEMA 14-50, an optional TT30 for travel trailers/small RVs, and most importantly a normal GFCI outlet. That way if someone shows up with a camper or really anything, you’re all set.

Better yet, it's available in a standalone, sits-on-the-ground form factor (google "RV pedestal").

Also, be wary of electrical gear on Amazon. They tend to be overpriced compared to a local electrical supply house, especially third party sellers because Amazon bites them for the cost of Prime shipping... but there’s also a huge fake, junk and counterfeit problem on there. This one is relatively safe because it’s “sold by and ships from Amazon”, brand it’s not the kind of thing counterfeiters go for. Just watch out.

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    Note that the "sold by Amazon" is vastly more important, as Amazon ships for third party sellers as well, which also counts for Prime.
    – Machavity
    Commented Jun 19, 2020 at 13:01
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    This is exactly what I was thinking about. Unfortunately, it looks like even the cheapest RV pedestals cost 3x as much as going with A. I. Breveleri's suggestion (per Google Shopping), so I think I'm going to go with the 4x4.
    – Nicholas
    Commented Jun 19, 2020 at 13:40

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