What is this white, pasty stuff growing in my outside electrical outlet? It has shorted our the circuitThis stuff is soft, not sticky. No bugs or moving things are present???

  • 1
    If you haven't scraped the mold off, could you add a picture of the faceplate you've removed showing the growth on it?
    – Ecnerwal
    Commented Dec 6, 2022 at 22:20

3 Answers 3


It's mold, or fungus, or slime-mold. Exactly what doesn't matter.

It's an indication that the outlet is getting wet. You need to solve that.

An "In-use" cover is one way to help that along, but this also eyeballs as a half-donkey-ed "outside outlet" with a non-weatherproof box in the wall, and who-knows what as a cover plate. Can't imagine it sealed too well against raw stucco, but that's how it appears to have been done, just as if it was an inside outlet.

A 3/4-donkey-ed approach would be to put on an in-use cover with a donkey-load of sealant to attempt to seal it against the stucco.

For the entire donkey, you'd want to replace that box with a weatherproof box and an in-use cover.

  • 4
    Isn't 3/4-donkeyed 50% worse than 1/2-donkeyed?
    – gnicko
    Commented Dec 2, 2022 at 1:52
  • 5
    When you need a donkey, but you only bother to get half of one, the job fails. When you get the whole donkey, the job gets done.
    – Ecnerwal
    Commented Dec 2, 2022 at 1:56
  • 6
    I took it as a polite form of "half-assed"....which kind of skews things about 180 degrees....
    – gnicko
    Commented Dec 2, 2022 at 2:04
  • 5
    does it not look like caulking? Commented Dec 2, 2022 at 5:58
  • 1
    @FreshCodemonger at first glance, yes. On a closer look, no. The left edge where it had grown past the outlet area and therefore was not ripped by having the outlet removed is the most obvious.
    – Ecnerwal
    Commented Dec 2, 2022 at 13:04

I'm pretty sure that's some sort of caulk or other glop that's been spread on the outlet. The coloring is far too uniform to be some sort of mold, and the way it's spread over that top outlet would not result from mold growth.

Of course, this doesn't change what is needed to fix things. The outlet needs to be replaced, and a decent cover installed. If wind-blown rain is apt to be a factor the box should be replaced with one that's weatherproof.

  • 4
    If you zoom in on the left side of the image then you'll notice a thin veil of webbing which is how fungus and mold typically grow. I hesitate to believe caulk was able to achieve these finer details.
    – MonkeyZeus
    Commented Dec 2, 2022 at 18:38
  • @MonkeyZeus To me, it looks like white glop with a bit of fungus growth on top and in the crevices. But yeah it needs to be weatherproofed: given the rust mark, glop-or-growth doesn't change anything.
    – user132372
    Commented Dec 4, 2022 at 7:53

I suspect that the installers might have used some sort of interior product to seal the outlet to whatever cover it had previously. Usually caulk or drywall. Exterior products are waterproof and will not promote mold.

I agree with Ecnerwal about water intrusion, and I suspect the source was whatever they put on for a face plate. See the dribble of rust in the lower left corner of the box? That screams that rain is hitting your stucco, running down it, and then getting into the box itself. I have a couple of suggestions here

  1. Upgrade to a GFCI. Be sure to buy an outdoor model (with the doors on the front).
  2. Buy an exterior extension ring and exterior caulk it up good (top and sides only to allow the box to breathe). Yes, your box will protrude more, but the new setup will better resist the water intrusion.

If you do that, any exterior cover should suffice.

  • 2
    Upgrade to GFCI only if this circuit is not already GFCI protected. And yes, regardless of whether you get GFCI or not, get an outdoor outlet, as the one in the picture appears to be an indoor outlet. An outdoor outlet will have the letters 'WR' for Weather Resistant stamped on it.
    – Glen Yates
    Commented Dec 2, 2022 at 15:45

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