Attempting to lock power cords in securely to prevent them from being accidentally pulled out of servers has been a source of great personal ingenuity. Wire brackets, nylon ties, Velcro and even epoxy! There have been more but I am a bit embarrassed to mention them.
I was excited when I found these locking cords because they do not require any “extra” anything to lock. The animation above shows you how they work and they can hold 30 lbs of pulled weight. You can see all the different sizes, gauges, types, specs and pricing at http://www.serverrackoptions.com/autolock.php