Those clips break easily. If something yanks on the power cord enough to pull it out, it will break that clip. If you have a wall mount the best thing to do is wrap it once around one of the plastic cable management arms and leave enough slack so the power cable reaches the connector on the BCM. This way if anything pulls the power supply, it will have to break the plastic piece before it disconnects the power.
In my experience, the only time I have seen power yanked out of a BCM50 it was the line cord coming from the power supply to the outlet. That was me drilling and rocking the ladder and instinctively grabbing at the first thing I could to keep from falling, lol.
15 years in Nortel phone systems; *nix and MS System Administration; and 3com and Cisco networking. Jack-of-all-trades in IT/Telcom, master of none.