I have a ranch house built in 1985 in Pennsylvania. The foundation is poured concrete. I want to replace one of the electrical boxes in the basement with a 2-gang.

What is the white plastic fastener seen in the photo (there are two). There is a shallow slot across the top of the metal pin in the center, but it doesn't appear to be deep enough to be a screw.

Should I try to unscrew it? Or just pry the box loose?


  • If you have a hammer-drill to drill in concrete you’re better off using tap-cons. Much more stout fastener. – Scottie May 25 at 14:28

I call them "pin anchors" but I think they have a longer actual name like "mushroom head drive anchors". The anchor is set by driving with a hammer, but can be "un-set" by unscrewing the pin because it has a twist thread on it. Just unscrew then pry out.

**enter image description here**

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  • p.s. they are not terribly strong in my experience, but maybe they worked ok here because the conduit is also strapped. If you are installing frequently used receptacles you might consider a more robust anchoring strategy. – Jimmy Fix-it May 23 at 22:49
  • yes, I would use 4 for anchoring a electrical outlet, but our australian plugs are about twice the size of american ones, so the two in the picture are probably enough. – Jasen May 24 at 2:02
  • I was able to unscrew the pin. It only came about halfway out because the threads only go halfway down the pin. The inserts pulled out of the wall easily. – Steve Fallows May 24 at 22:08
  • Perfect! As designed, with the pin pulled back, no more outward pressure on the plastic ans it can be removed. I have had them get stuck and had to use a cat's paw to pull them... – Jimmy Fix-it May 24 at 22:21

It's just a plastic wall plug, sometimes called an expansion anchor or by various brands names. https://www.confast.com/product-1-4-x-2-nylon-nail-it-round-head/

Sometimes you can successfully rotate and remove the pin, but a flat claw hammer will normally take them out pretty quickly.

If installing a new box in the old holes you can use a more permanent replacement version that are often called "lead anchors", even though they aren't made from lead any longer. https://www.homedepot.com/p/Red-Head-1-4-in-x-1-in-Hammer-Set-Nail-Drive-Concrete-Anchors-25-Pack-35200/100129334

When installing these anchors often times the hole in the electrical boxes is a bit to small for the anchor to slide through, you can usually slide a good quality nut driver or deep socket over the pin and gently persuade the anchor through the hole with a hammer.

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  • you won't get claw hammer into that electrical box. but if you chisel the flanges off then locking pliers might do the trick. – Jasen May 24 at 2:04
  • You just claw the whole box off the wall. – NoSparksPlease May 24 at 13:14
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    The anchors in second link are made of zinc, not lead. – jpa May 24 at 17:59

They are called nylon nail-its. Drill 3/16" or 1/4" hole, push them in then hammer them down till snug. Just take a narrow-tipped flat screw driver and back them out. No big deal.

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