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This junction box cover is labeled "under side" on the side that is supposed to go inside the box. Why? What is different about this side?

enter image description here

Here, for comparison, is the other side. enter image description here

EDIT: In light of the accepted answer, here are close ups of the respective edges. It's really very subtle, but perhaps there are random instances where there is more to it.

enter image description here

enter image description here

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  • Barcode stickers are unsightly, I guess?
    – MonkeyZeus
    Jan 20, 2021 at 13:47
  • Is there any noticeable difference such as sharper edges or smoother surface?
    – MonkeyZeus
    Jan 20, 2021 at 13:48
  • that is a typo.
    – ojait
    Jan 20, 2021 at 13:59
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    @ojait Agreed, should be one word. As it stands it translates to "You have to install it under the side."
    – MonkeyZeus
    Jan 20, 2021 at 14:18
  • 1
    If you're at the store again, check their stock of covers and see if some are less perfect than yours. I would imagine that towards the stamp's end-of-life it produces a less perfect result.
    – MonkeyZeus
    Jan 20, 2021 at 18:02

4 Answers 4

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All, the stamp "Under Side" actually has to do with the galvanized coating that is placed on the steel when it is created. The UL requirement for coating is different for the outer facing surface than the inner facing surface. The coil that this product is created from could have two different thicknesses should the end user, RACO in this example, decide they wanted to manufacture their products in that manner. At the moment, RACO actually does not utilize different coating thicknesses on this product, but the stamp remains.

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  • That's very interesting info! Do you have something you could point to in terms of a source for this info? That would move this from a "good" answer to a "great" answer
    – FreeMan
    Oct 12, 2021 at 14:06
  • Another plausible answer! The UL does not make it easy to obtain their standards documentation. Web searches for them inevitably lead to UL marketing material sucking you in to talking to their sales people. Here is such a reference for metallic surface coatings. It says nothing about the two sides of an electrical box cover, but it wouldn't. It would be great if @DTU had first-hand knowledge of specific standards for the inside and outside of a metal box! But unfortunately, we should not expect links to such.
    – jay613
    Oct 12, 2021 at 14:38
  • OMG I wonder if the UL stamp on my cover only applies to that side of the cover? 8-O
    – jay613
    Oct 12, 2021 at 14:40
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    The UL stamp applies to the entire product. As mentioned, the UL has standards for coating thickness on both sides. For a component to pass UL it must meet the requirements of the entire standard. As far as a source, I am in product management at Hubbell.
    – DTU
    Oct 12, 2021 at 15:26
  • Thanks for an authoritative answer to a long-standing mystery!
    – jay613
    Oct 17, 2021 at 3:24
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You will notice the cover is stamped and this keeps the rough. Sharper edge on the correct side. This is what I was told by a factory rep even though the rough/sharp side is down (he said it actually helps hold the cover in place)

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  • 3
    I don't buy this but you get an upvote for having spoken to a factory rep. At least that's a data point. He was probably making it up. If the (non existent) rough edges are helping to keep the cover on, you should probably just tighten the screws a bit! :)
    – jay613
    Jan 20, 2021 at 17:13
  • @jay613, I would fully agree as to me the sharp edge should be away from the wires. I was talking to a Hubble rep as you can feel the edge on the bottom and he responded with the answer right away so I figured he had been asked before. You can feel the difference from top and bottom and raco/ Hubble is the brand I primarily use on both commercial and residential.
    – Ed Beal
    Jan 20, 2021 at 17:39
  • Ok Ed and @monkeyzeus I have to hand it to you. I have two of these covers spare so I fetched them and I'm sitting here rubbing the edges gently like some kind of galvanized metal pervo, One of them, there is no perceptible difference, but the other one you can definitely tell the "underside" has a bit of a, well, not sharpness but a kind of a rasp, shall we say, along the edges of the cut whereas the top side feels a little rounded at the edges. As monkeyzeus suggested, maybe as the dies get dull this happens. Amazing to have testimony from the very manufacturer .. thank you.
    – jay613
    Jan 20, 2021 at 21:31
  • The smooth side is the "underside" so either the rep was wrong on that specific point or we all interpret "underside" incorrectly. I'm pretty sure "underside" means inside the box and the idea is to protect wires from sharp edge, not to assist with keeping the cover secure ... which is the job of the screws.
    – jay613
    Jan 20, 2021 at 21:36
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    @jay613, possibly they meant that the screw heads pressing against a rough surface will help keep them from backing themselves out over time, in the same way that the rough edges of a lock washer do. In that case, the smooth side would indeed be towards the wires.
    – Nate S.
    Jan 20, 2021 at 22:04
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It’s so you can see ul stamp if it gets painted

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    Now THAT at least passes the sniff test! It's plausible, logical, and the intent is reliably achieved by following it. May I ask how you know this?
    – jay613
    Oct 5, 2021 at 20:51
  • I agree this makes a lot of sense! I, too, would like some sort of supporting evidence.
    – FreeMan
    Oct 6, 2021 at 11:49
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    I just wrote to Raco Technical Support, and got an answer! And it's close to this one. But it isn't this one. See my answer.
    – jay613
    Oct 11, 2021 at 14:00
  • The reason I'm not marking this correct is two: 1) Manufacturer provided a different, although less plausible, answer, and 2) it leaves open the question, instead of stamping Under Side, why don't they just stamp UL on both sides???
    – jay613
    Oct 11, 2021 at 16:35
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I wrote to Hubbell Raco Technical Support and got an answer! I'm not sure it's the right answer, I like @jeffrey-s-anderson's one better. But FWIW, the answer from the manufacturer is that it is "intended to have the RACO name exposed after installation".

That's right, if you believe it, it would seem to employ an ambiguous compliance-related fear reflex in electricians to obtain free marketing.

You might ask, why don't they just stamp "Raco" on both sides? Or why, for that matter, don't they stamp Raco and UL on both sides?

The answer to my query included a nod to that question, but not an answer. There may in fact be no good reason for this!

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  • Thanks for taking the initiative to actually ask the mfgr! I'd guess that it's cheaper to stamp the UL & mfgr name on one side only, even with the added expense of stamping in the Under side admonition. How or why, only the bean counters can know...
    – FreeMan
    Oct 11, 2021 at 14:10
  • I believe now that this is a correct answer, but a side effect of the correct answer. Not a marketing ploy, but if there is truly an under side because of potentially unlike galvanization on each side (see Correct Answer) it would make sense to put the name on the outside.
    – jay613
    Oct 17, 2021 at 3:23

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