Ah yes. I have one too! This is from the mid 1960s.
I was studying Electrical Engineering and during one vacation was working at what was called the "Postmaster General's Department" in Australia (they had provided me with a scholarship). In other words, Posts and Telegraphs encompassing communications such as TV, phones and even the ordinary mail.
Anyway, my boss, the Chief Engineer decided to give me some field experience. So I went to a facility high in the mountains. It was a sort of relay station for microwave links between Sydney and Melbourne. Very important as it (as well as TV) carried all telex, phone calls etc between capital cities.
The local engineer showed me the various workings, including the triple redundancy with lots of stuff. He proudly opened one rack with multiple power supplies and various transmitters & receivers.
I said "So, if any one of these rack units fails, another one will automatically take its place?" "Yes" he replied.
"Can I try it?"
So I did. I pulled out one of the rack units and all was good.
Then I tried to put it back in and somehow got things crooked and pushed way too hard (I was a strong guy).
There was a huge "bang". A huge flash. Sparks flew everywhere.
Then- dead silence. All dead. Everything dead (except the humans)! It was pitch black (no windows in there).
After one minute's silence (during which I was seriously considering if I had any future), a couple of dim light bulbs came on. Then all seven bright red phones started ringing. Then a huge (about 100kW) generator started up. Then various lights came on.
I had wiped out everything. But they got telephones, telex and stuff going in about 10mins. But Television took until next day.
That was the end of my work experience in the field. The rest of the time, I was confined to HQ with a drawing board updating diagrams!
Like the molten steel-never forgotten.
Also, I learned something about systems which allegedly can never fail......