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In the U.S., our plugs have always had these little 1/8 inch or three-millimeter holes in them. But if you ask people why we have them, most people have no idea.
What we do know is that for many of us, these little bald-looking plugs, as I like to call them, just look wrong. The truth is, for the last 75 years, these holes haven’t served the purpose at all until now. I’d like to introduce you to an ingenious method that a bunch of manufacturers are using these holes for that most people in the US have typically never heard of. And ironically, it all ties back to why the holes were added in the first place, but with a twist. Let’s start by addressing the three most common myths about what these holes might be used for.
Myth 1 – Locking The Outlet
Myth number one: putting locks or zip ties in the plugs to prevent the device from being used. Nope, that’s just something people started doing because the holes were already there. The internet is full of tales of vengeful fathers placing tiny padlocks on the plugs of Nintendos and Xboxes and PlayStations, thus forcing kids to play outside and expand their minds and study the wonders of mathematics, or realistically, head down the street to Jake’s house to play on his PlayStation.
Myth 2 – Save Money by Using Less Metal
Myth number two: it’s to save money by using less metal. This just doesn’t make a lot of sense. It’s such a small amount of metal, and if it were for cost savings, they’d likely design a version that focuses on cost savings, like this one here. Speaking of which, they’re also not intended to make it easier to do shady electrical work like this, though I may or may not have been guilty of doing that once or twice as a quick test.
Myth 3 – It’s for Lining up the Blades in the Manufacturing Process
Myth number three: it’s for lining up the blades during the manufacturing process. While I have seen evidence of that being done, like in this video here, this is more of the exception than the rule. In most cases, holes aren’t used at all for alignment, and when they are, that’s yet another way to take advantage of something that already existed.
To understand what these holes were originally for, and to see how this ties into the clever way they’re being used now, we have to travel back over 100 years to look at the original designs for plugs. It’s weird to think about now, but when electricity was first being run to homes and buildings in the US, in the late 1800s and early 1900s the only electrical standard at that time was Thomas Edison’s bulb. That bulb came with a certain fixture, also known as the E 26 fixture. It’s what we still call it today. As a result, homes were wired up with this new thing, with electricity, but only with Edison sockets, like you see in the picture here, receptacles or outlets hadn’t yet been invented.
These light sockets were the same fixtures we still use today, with a hot wire that connects the button on the top and then a neutral that takes care of the threads all around the bottom, which were, as it turns out, 26 millimeters in diameter. Hence the name e 26 or Edison 26 millimeter. That’s how it got its name.
In subsequent years, as inventors came up with fans and irons and vacuums that needed to be plugged in, they actually used light bulb socket plugs like these to power them. You can imagine how inconvenient that must have been.
I made my own version of this for a fan, and you can see that it’s going to be pretty inconvenient to use this with all the twisting and everything.
That’s when we started seeing early versions of this device. A way to convert Edison socket into a plug that can be used for multiple devices. Just thread it into the socket and put a plug on your appliance, and voila, no more tangled wires, right? Well, not exactly. The thing is, there was a format war, so multiple inventors came up with multiple different types of plugs like this, some were tandem, like this, and some were parallel. Early receptacles often accommodated both, since a standard hadn’t yet been agreed upon.
Eventually, manufacturers got together and they all agreed on the designs of my boy, Harvey Hubble from Bridgeport, Connecticut. Now, on a side note, I was raised in Connecticut, but never heard of the man who invented not only the plug, the modern plug, but also the pole string socket, like this one here. Hubble’s patents included what he called detents, or indentations in the prongs of the plug that were used to help secure the plug in place thanks to a mating set of grippers in the receptacles. His original plug designs were actually pretty similar to a headphone jack, where they sort of snap into place.
But here’s the rub, everybody wanted to be the one to come up with the exact design that our nation would end up agreeing upon. So we started to see patents for partial indents, detents, slots and eventually holes, which were very easy to manufacture. Our man Harvey Hubble ended up patenting most of the designs we’re now familiar with, including several variations like this one, the plug as we know it today, was born and became the standard in the United States, and holes became standard to help hold the plug in place by the 1950s.
Even though most US plugs still had holes in the blades, receptacles that provided a matching latch mechanism of any sort were all but gone. This may be due to the fact that there were safety issues with making a receptacle in the wall that holds too securely onto the plugs. Think of what happens when you trip over a cord connected to a traditional barrel adapter like this for a laptop, as opposed to a MagSafe. Typically, you prefer it to break free cleanly and not bend or destroy the plug on the device, right? It’s the same thing with plugs in the wall. Too firm a connection to the wall can actually be a bad thing.
Outlets today use a tight fitting receiving end for the plug blades, and they tend to hold in really well and last for decades, despite being very inexpensive to produce, except in hotel lamps like this one, these things are pretty much guaranteed to be sloppy, loose, a total shock hazard and extremely frustrating. They seem to have a built in feature that makes them barely work when you go to bed and then loosen to the point of not working six minutes after you fall asleep. But hey, it’s not like you need your phone to be charged while you’re traveling, right? In any case, this all means that for the better part of the last 75 years, the holes in our plugs have been largely useless. They haven’t been used to secure the plug in place for decades.
Here are some of the coolest products I’ve seen in this space in ages, all of which work thanks to the previously useless holes in your plug blades. These are locking extension cords. This is the perfect application for creating a secure plug connection. You can still unplug the extension cord from the wall or receptacle easily, but when you’re dragging a tool around that’s connected to an extension cord for yard work or construction cleaning or other tasks, there’s nothing more frustrating than this, and it happens all the time. The common solution for this is to take your whole plugged in assembly and tie it in a knot. Yes, you can do this, and believe me, I have, but then you’ve got a huge knot dragging around your job site or your yard that catches on everything and can still come undone. These locking plugs are easily unplugged, either by sliding a lever or pulling back on a collar, and they’re generally rated to withstand up to 80 pounds or 36 kilograms of force.
I took a look inside these to see exactly how they work, and sure enough, they take advantage of the holes inside the blades, just like our boy Harvey did 120 years ago. So these are essentially using the exact same technology and principle that the plugs were originally intended for only now with modern conveniences and on extension cords.
This $12 plug locker replacement extension cord end uses spring loaded ball bearings that pop into the holes of the blades automatically, and you can then slide the lever on the outside to release them, which allows you to release the plug.
This lighted powersmith extension cord works the same way and costs just 27 US dollars for a 25 foot cord with the locking mechanism. I think that’s a pretty decent deal.
My favorite application, however, is this DeWalt extension cord. It costs more than the Power Smith coming in at $40 but it lights up at both ends and has a terrific locking mechanism, a collar slide that easily locks when you plug something in, and then won’t release unless you slide the collar back. This thing is seriously heavy duty and carries a 4.9 out of five star rating on Amazon. People love it.
I took it apart as much as I could to see how it works. And rather than ball bearings, this one uses a small spring loaded metal hook, which is actually more reminiscent of Harvey’s original design. There are several other extension cords out there that feature the locking plug, like these. And this video is not intended to be a comparison video, but these seem to be a great value based on price, reviews and durability.
One of the big questions I had when buying these was whether or not they are compatible with all plugs. Now, remember these funny looking no hole plugs that we looked at earlier? Well, as you might have guessed, they don’t work with these types of plugs, since they rely on the holes in the plug, but they work fine as traditional extension cords with them as well.
That said, nema, or the National Electrical Manufacturers Association, which creates the standards for our electrical devices, clearly states that plugs are not required to have a hole in them, but if they do, they have to follow a strict set of guidelines as far as the placement and positioning of where those holes are on the plugs. This means that virtually any plug that has holes should have the holes in the same place, and will therefore work well with these extension cords locking mechanisms. And honestly, that tracks with my testing as well.
Every plug I tested worked totally fine on each of these locking mechanisms. It’s worth noting here that there are other ways to keep your plugs from coming free of your extension cord. There’s the aforementioned knot which is probably the most common method.
There are plug locks like these, but they cost almost as much as the plug locker. They do come with the added benefit of providing some protection against the elements.
There’s also the good old velcro or hook and loop. If you’re working outdoors or in a messy environment these can collect debris and dust. But if you’re just inside the house, then this could be a good option and potentially free option if you already have some velcro straps kicking around the house.
So to my fellow Connecticun – Harvey Hubble, thanks for your manly mustache and for giving us the modern plug, even though it’s still inferior to the brilliant type G plug used over in Britain. More on that right over here, I’m Nils with learn to DIY. Thanks for watching in the US.
Don’t throw out the idea of purchasing an older home. I have a post on Common Fixable Problems with Older Homes. Click HERE to learn more.
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