That may be the theory, but believe me, in practice it's not always true. I ended up with a reprimand on my service record when a technician working for me in

That may be the theory, but believe me, in practice it's not always true. I ended up with a reprimand on my service record when a technician working for me in the Air Force did precisely this, cutting the ac cord, with a pair of uninsulate scissors, which then went flying across the room. The reprimand was because I hadn't put measures in place to stop technicians using uninsulated scissors for technical work - fair enough. I'm guessing that the ground wire in the cable hadn't been correctly hooked up to the ground pin in the plug, a not uncommon flaw in cables...