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The wall plates in my kitchen suddenly bowed outward like this: Warped outlet cover on wall

Additionally, there seems to be condensation present on the back of each plate, suggesting that this was a thermal event of some kind. Considering that:

  • This occurred overnight
  • It happened to all four receptacles on that circuit and no other plates in the house
  • Nothing was plugged into them at the time
  • The breaker did not trip
  • The circuit still functions normally
  • My house did not burn down

What might have caused this?

Potentially relevant background info:

  • My home is new construction
  • The house immediately adjacent to this wall is undergoing construction presently
  • The wall is tiled (as visible in the photo)

Edit: photo with plate removed, as requested in comments Receptacle without cover plate

  • Is the wall hot? Are the receptacles hot? – Lee Sam Jul 25 '18 at 20:28
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    The install looks perfect. Just a bad batch of cover plates? Use metal ones. I don't see any reason to add an extension if it's a plastic box. – Mazura Jul 26 '18 at 2:51
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    Were the receptacles screwed in so tightly that the "ears" broke the glazing on the riles? – DJohnM Jul 26 '18 at 4:21
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    Is this a common wall with the "adjacent" house that's under construction? – DJohnM Jul 26 '18 at 4:23
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    @Mazura potentially, yes. I think that’s what I’m going to do. – jerj Jul 26 '18 at 9:37
5

You typically don't use domed head screws to mount the receptacle to the box (they stick out too far). You can get away with it if the back of the wallplate has a big indentation for those screw heads, but they usually don't.

Those screw heads hold the wallplate away from the surface of the receptacle, so there is a gap between the wallplate and the center of the receptacle. If you then tighten the wallplate attachment screw to pull the center tight, the wallplate will warp like that.

Options:

  • Replace the receptacle mounting screws with flathead screws.
  • Snug the attachment screw just enough to hold the wallplate on. Don't tighten it until the wallplate bottoms out against the receptacle.

Additional thoughts:

  • The wallplates were fine for a long time and suddenly bent.

    The wallplates in the picture look like plastic. If they were strong enough not to immediately crack, they could have distorted locally, like a dimple under the attachment screw and some stretching around the receptacle mounting screws, and been under stress. The plastic could gradually degrade and weaken over time through stretching, micro-cracks, etc., adjusting itself for the distortion, until the highest stress area across the middle suddenly failed.

    It is the same product installed in the same way at the same time, so failure would be expected to happen in all of them at roughly the same time. There could have been some other factor (sunlight, heat, temperature change, whatever), that pushed them all past the final failure point at the same time. That's all speculation, but materials do behave that way, so sudden bending long after installation wouldn't require magic.

    Also, consider that the wall plates wouldn't bend that way unless there was some kind of force acting on them in the same way as what I've described here.

  • The bend looks much greater than the screw head height.

    That's partially an optical illusion. In the picture, the distance between the wall and the wallplate at the middle and at the ends looks like it's in the ballpark of the screw head height, but the difference would be expected to be greater.

    In the first picture, look at one of the receptacles, say the top one, and compare where the wallplate comes on the top edge vs. the bottom edge. The difference is only millimeters. That's in the screw head thickness range.

    The bend looks exaggerated because you're seeing the effect of the bend on the entire length of the wallplate, which is longer than the screw distances, and possibly even additional warping because of the distortion of the wallplate.

Whether or not the problem is the screws is easy to determine, though. The fixes are trivial. Do either one. If the problem repeats, you will know it was something else.

  • That's it! It's the domehead screws. The condensation on the back was from a cold wall and low air circulation. – Jim Stewart Jul 25 '18 at 21:33
  • @JimStewart I doubt the domed shaped screws are the cause, because the back of the cover plate is concave, isn’t it? – Lee Sam Jul 25 '18 at 21:40
  • @JimStewart Hmmm...I had to take one of my plate covers off and I don’t think a domed head screw could affect the plate...especially like that. – Lee Sam Jul 25 '18 at 21:47
  • I’d blame the cat. – Lee Sam Jul 25 '18 at 21:48
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    @fixer1234 But the op said it happened “suddenly” and it happened “overnight”. I’m telling you...the cat did it... – Lee Sam Jul 25 '18 at 22:01
1

I have not seen anyone advise a box extender is needed here. This would allow the use of the screws provided with the outlet.

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    Can you clarify how adding a box extender would solve wall plates curling? It's not clear how this relates to the question. – Machavity Jul 26 '18 at 1:11
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    I should have resisted the urge to mention box extenders. I was not addressing the OP's question. – Jim Stewart Jul 26 '18 at 7:18
0

When a box extender is called for I find this type most convenient because it slips inside the existing box and the flange fits against the finished wall. The back part can be trimmed with tin snips or perhaps a utility knife if it is not needed or interferes with wires or connectors in the box. But sometimes the hole in the finished wall is too large for the outer flange of the soft plastic extender and the hard plastic extender is needed.
Softer plastic box extender

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    Can you clarify how adding a box extender would solve wall plates curling? It's not clear how this relates to the question. – Machavity Jul 26 '18 at 1:09
  • I wasn't suggesting that the lack of box extenders had anything to do with the bowing of the wall plates, but merely observing that technically they might be required if the box is recessed as far as these are from the finished wall. These used to be metal and called "tile extenders". – Jim Stewart Jul 26 '18 at 7:14

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