Just a note on there. I had one whose battery had failed, and I tested what happens if you twist the cable. I latched it around another padlock, and twisted until it broke. Getting the twist started takes a bit of oomph, but once you have the cable twisting around itself, more twists don't require a huge amount of effort - the lock body gives you all the leverage you need to put a fearsome amount of force on the latch and cable mounting.
I wasn't sure what would break first - the latch, the crimps on the cable, or the plastic anchoring the fixed end of the cable. In my case, the cable came out of the crimp at the fixed end, and the latch let go, pretty much simultaneously, separating the cable from the lock body completely. So I'm reasonably happy that
in extremis, the lock can be destroyed if it fails. Here's what the wreckage looked like:
Note that the latch actually seemed OK afterwards - apart from some strain marks on the inner side of the housing, nothing appeared to have broken and it seemed to operate normally. The marks are hard to see, but note that under strain the twisted cable was pulling basically at right angles to the latch and attachment holes on each side.
There are some caveats to this as an emergency escape method:
- You do need to be able to get a good grip on the lock to and be able to twist it, which could be difficult if only one hand can reach it, or it's only just in reach.
- The lock needs to be attached to something that will hold the other end of the twist.
- Doing this puts quite a bit of force on whatever is holding the other end of the twist - if it's a buckle with a locking tang, there's a good chance that you'll twist off the tang or otherwise damage the buckle - this will probably still get you out. But if it's locking a flexible strap, it's going to twist the strap, and depending on the width, stiffness et c you could twist the strap quite tight before you can get enough force to part the lock.
So YMMV; I'd definitely consider this a "Plan C". Plan B for me is usually to arrange things with two locks such that only one need release to escape - that may be using two "in series" to some kind of tether or two keys to the "primary" lock secured separately by timer locks, or one release allowing access to tools cut oneself out. That approach doesn't solve the question of early release in emergency.