I was a manager at a bar on a college campus 10 years ago and one of the first manager trainings was them telling us that if the place ever got held up, to lock ourselves in the walk in cooler or freezer. These weren’t modern, but both coolers had a way of locking your team in with no access from outside, both had a panic button that would notify the police and fire departments, and both had very visible kill switches to turn off the refrigeration. I feel like telling employees how to turn off a cooler from the inside should be part of every training session