One of my internships in college was working for a company that made robotic equipment for manufacturing, and one of their customers was Silicon Power Corp, who made these crazy huge 5000 amp diodes used in mag lev trains and some classified military applications. My job as the FNG was being in the customer's factory overnight (usually alone), working on our automated test and manufacturing equipment, while the factory was closed in order to not interrupt their normal production.
They'd leave these diodes running on their automated test and burn-in systems overnight while I was working, and the test systems consisted of these room-sized racks built out of 2x4 framing, holding hundreds or thousands of coffee can-sized electrolytic capacitors, big Farad-sized jobs. The capacitors would charge for maybe ten minutes, and then all discharge in a single impulse through these diodes meant to handle 5000 amps continuous current and impulses probably several hundred thousand amps (classified, I don't really know). Each time one would fire off, it sounded like someone had fired a Howitzer right there in the room with you. It was recipe for a heart attack, or at least crapping your pants.
The trouble was, there were dozens of these systems in this big dark factory, all charging and discharging on seemingly-random schedule. The huge wooden racks holding these banks of capacitors would groan and creak as the caps were charging up, to the point where you could start to get a sense when one would be ready to fire off... but that only made the anticipation worse!
One thing I remember vividly, was that the "wire" through which these capacitors discharged into the diode under test, was about 1-1/4" to 1-1/2" diameter stranded wire, and as stiff as any 1/2" rebar you ever tried to bend. I remember trying to bend a length of it over my knee with limited success, when cold, but the stuff would whip like a piece of yarn each time those capacitors discharged through it.
I was so glad when that contract was completed, and I could stop working nights in that creepy factory. But I have to admit, no loud noise startles me, anymore.