I work for a company that designs back-up power systems for data centers and hospitals. As my boss says, "Our job is to make sure that when the lights go out, the lights don't go out."
In every data center (or server room, or whatever the client calls it, it's just a pile of power load to us) there is something called an EPO, and is required by the National Fire Protection Code. EPO stands for Emergency Power Off. It is the real Big Red Button. When it is pressed, all power is cut on the power system level; that is, it is the equivalent of pulling the cords out of the machines. No more power available, everything is off. All you hear is the hum of fans spinning down.
Needless to say, most IT people for these clients protest the inclusion of an EPO in the first place. Their job is to make sure that these machines never turn off, so why should they allow a big button to turn them off? Basically, it's so that if there is a fire, and a firefighter comes in spraying water, he won't have 600 Amps at 208 Volts coursing through his heroic body. The EPO is there for a reason. It cannot be omitted.
So, the next best thing to eliminating a big power-off button is making it hard to operate. This makes sure that you don't have somebody accidentally leaning against the button that makes your company stop working.
There are plenty of methods for this. Some have an In Case of Fire, Break Glass enclosure over the button. Others have a series of keys that must be turned before a button can be activated. Usually, there is an auxiliary alarm that goes off whenever one of these preventative systems is activated, so you can stop them from dumping all the company's data in the nick of time.
It seems there was an ambitious security guard. A fire alarm had gone off in the server room. He went in, investigated, and found no fire. No problem there, check out everywhere else. No fire. Oh well, somebody overcooked a pizza in the microwave, no big deal.
But that damn alarm just kept going off. He had to find a way to shut it off. Back to the server room. How do you shut off that alarm? Any switches or dials? Well, there's the light switches... no good. Hey wait, here's a little box on the wall with no label (it was supposed to be installed the next day; the new EPO had just been installed two days previous). Hmmm, it has two key switches in it. Well, when all else fails, start flipping switches. He turned both keys.
The fire alarm did not stop.
He returned to his desk.
An example was later made of him.
This is a true story that was passed around the office in my first month of work. Apparently, the client tried to say that our system was faulty, and that the security guard hadn't hit the EPO. Then they all watched the surveillance tape, and saw him casually walk up to the box, turn both keys, and walk out. You could hear a pin drop in that room.