Corrected entry: The electromagnet locking down the vault could not have simply deactivated if the power was cut. The steel used in the construction of the vault would have developed into a permanent magnet (remanence) thus preventing the vault from being opened. Removing this remanent magnetism is very difficult, one of the simpler ways is to heat the material to its curie point, which around 1500 degrees Fahrenheit (816 degrees Celsius) in 9.0% carbon steel, the terrorists did not do this or any other method to remove the remanent magnetism.
Rlvlk
8th Aug 2007
Die Hard (1988)
31st Jul 2005
Die Hard (1988)
Corrected entry: When Bruce Willis throws the C4 (stuck with a chair and a computer screen) down the elevator shaft, the C4 explodes. C4 is very manageable and won't explode through physical force; even a bullet won't make it detonate. You'd need the blaster caps or some other explosion to set the C4 off. For more info on C4, read this: http://science.howstuffworks.com/c-42.htm.
Correction: My understanding of the scene was the monitor was there to ad weight to the chair and keep the C4 in place. The detonators set off the C4, not the computer monitor.
The detonators won't randomly set off the C4. That's not how detonators work. The mistake is accurate.
Not "randomly". CRT screens / capacitors famously store a dangerous level of electricity for a long time after being turned off, and smashing the screen / damaging them will be enough to discharge it, which would in turn trigger the detonators and thus detonate the C4.
Correction: If the electromagnetic lock instantly turned the steel vault into a permanent magnet, then it would render the lock and the vault useless. No one could ever enter once the lock was activated. Electromagnetic locks are used in many high security areas and that is how they work: Turn off the power to the magnet and the door opens.
Rlvlk