I think the worst "shock" I ever got was when I got ahold of a subcycle generator output for the telephone system for a large office building.
It provided the ringing voltage for the phones.
It is 90V @20hz.
It was not so much the voltage-but the freq. I could feel my bones banging against each other.
The second anode of an tube TV will "wake you up" also.
I have never got on an office side ring generator in a step office. That would have to bite.
What Ivan is talking about is regular phone line uses office battery -48v to provide a current loop for the microphone and earpiece. AC of 90Hz is sent to fire off the ringer. Even after a few miles of cable it still bites. It's much worse in the office.
In electro-mechanical offices there was a single ring generator. It was an AC generator and a ring bus was run between the frames. In the newer electronic offices this was replaced by a single switcher type power supply of standard frame height and no moving parts. Lot less current too.