Wrong way to coil an extension cord #1: Wrap it around your elbow
I’ve seen assistants practically chewed out for making this mistake. One day as a 12-year-old, you were helping your dad in the garage and he taught you to coil up extension cords by holding one end in your left hand and then with your right hand to wrap the cord the length of your forearm, tightly around your left elbow and then back through your left hand. This results in a tightly coiled cable that may store neatly, but which functions terribly and wears out sooner. How does it function terribly? No matter how you beg and plead, a cable coiled like this will not lay flat on the ground. The number-one job of cables is to deliver electricity from A to B. The number two job is to not trip anybody. And any coil that won’t lay perfectly flat on the ground presents a tremendous trip hazard. Not only that, it shortens the effective length of the cable, which can be problematic, and potentially worst of all, wrapping a cable with tight bends like this can kink and ultimately break the wires inside. The only thing worse than a kinky cable is a broken one. Coil cables around your elbow, and you’ve got a recipe for both. Cease this practice immediately.
Wrong way to coil an extension cord #2: Coiled too tight
For practically all of the reasons mentioned above—minus the sharp bends that lead to breakage—don’t coil a cable too tightly, in too small of a circle. You may think a big, looping coil seems messy, and you want things to be nice and orderly, right? So you coil the cable in a nice, tight, round little bundle. Yay. Now leave it that way for a day or two and then try to unspool it neatly on the ground. Good luck with that. Your cable will be twisted up like the wire on your kitchen telephone in the 1980s. It won’t lay anywhere close to flat and it will present multiple and serious trip hazards. Do not coil cables too tight in an effort to store them in an orderly fashion; you’ll only make things more difficult when you go to use the cable.
The right way to coil an extension cord: Loosely and naturally, using the over-under method
I know it sounds like I’m saying extension cords are sentient beings. Not quite. But they do have a way they like to be wrapped. (Garden hoses, coincidentally, work in much the same way. Now I’m helping you in the yard, too!) With one end of the cable in your left hand, hold the end of the cable pointing to your left and with your thumb pointing to the left as well, as pictured below.
Now use your right hand to grab the cable a few feet away (as little as, say, 24 inches and a max of probably four feet, depending on the cable) and hold it with your right hand and your thumb pointing to the left, in the same direction as your left thumb. Now bring the cable from that point up to your left hand and deposit it there, releasing with your right. You’ve created one loop. Now repeat the process, but with each new grasp of the cable you should alternate the direction your right thumb points. When it points to the right, swing the cable a full 180 degrees to the left as you bring it to your left hand. This will create the over-under alternating pattern that gives this approach its name (the over-under method) and keeps cables memory-free. Better still, this method makes cables incredibly easy to unspool without tangles. Just hold one end of the cable and throw the bundle in the direction you want to go. Watch as it unspools perfectly and without tangles. This is a huge time-saver if you work with cables on a regular basis.
For cables that already have memory that you’re trying to train to lay flat, I start with the same over-under approach, but vary it based on how the loop of cable wants to lay. Is it twisting in one direction? If so, untwist it by turning either hand in the opposite direction. The goal is to create a loose coil of cable that has no tension on it anywhere. It’s tension that creates memory and prevents a cable from laying flat and coiling properly in the future. Once it has been coiled and uncoiled this way a few times it should lose its memory, allowing you to resume the standard over-under approach going forward.
Once coiled correctly, the cable can be kept in place with a small length of string tied to one end of the cable, or use hook-and-loop cable ties to keep everything orderly for storage and travel. These cable ties are almost as important as the proper coiling technique in the first place.