Building a mollyguard to protect a power strip.

If you've been to anyone's house in the last 20 years you've undoubtedly seen a bunch of stuff plugged into a power strip. Once found in office most of the time they've become as essential to everyday life as mobile phones. However, everybody has also encountered the most common failure mode of power strips - accidentally hitting the power strip and accidentally turning everything off.

This is far from a strange problem; if it's got a power switch chances are somebody's hit it by mistake. The obvious thing to do is put a cover of some kind over it. It's even got a name, a mollyguard, after the mythical daughter of an IBM programmer who accidentally crashed a mainframe by playing with the buttons. While they're fairly common on industrial machinery they are not on consumer power strips. But for the most part they're fairly easy to build and add.

The last time I re-did my rack I bought a couple of industrial power strips with solid steel bodies that have the power outlets placed in a way that mostly works for me (wall warts notwithstanding). I knew from a little experimentation that the power strips' bodies are magnetic so a small handful of magnets would are for holding a cover in place. I knew from visiting friends with little kids during the Before Times that after-market power switch covers are a thing. After taking some measurements and doing a little math I figured out that these wall switch covers are a good fit for the power strips I have. Additionally, those switch covers have a narrow slot running over where the switch goes so that you can reach in with a pen or something and flip the switch without having to pull the cover off. I don't turn everything off at the power switch very often (only when I do a teardown of my stuff, which is at most once a year) so that's not a big deal.

The only other thing? A hot glue gun. That's it.

To make things a little bit easier I used my bench vise to hold the switch cover upside down. It didn't need to be clamped down though the curve on the top ensured that it wouldn't lay flat on my work bench. The rest of the build is about as simple as it gets: A dot of hot glue, drop a magnet into the glue, press down. Rinse, repeat. Be careful when placing the magnets; you don't want them to jump up and stick to each other because, well, they're magnets. If you're careful you can let the glue cool off a little, then flip the guard over on a non-magnetic surface so that they'll reach a more or less even placement.

The magnets might attract each other and flip off of the plastic. In that case, just peel the hot glue off and try again. It happens. Also, wait for all of the glue to cool and set before you clean up the little doodles of glue that get everywhere. It doesn't hurt to press a magnet into the blob of glue and let it set up for a minute or so. There's no rush. If you have to start over, start over. This is easy but can be a bit frustrating. When taking the pictures for this article I had to try a few times to get everything right. Also, one of the magnets (the one in the bottom-right corner) isn't oriented properly (the magnetic pole facing up isn't the same as the other three), which might be a problem later.

Then, it's just a matter of exposing the power strip (you probably won't have to unplug it, or anything plugged into it), dropping the cover over the switch, and putting it back.