According to PaPaPeng :

Doesn't sound right. The juice to drive a microphone is in the low DC
voltage value and runs on milliamps. Its even weaker than the current
that drives the big speakers. Water or no water I have never come
across anyone being zapped by a frayed microphone wire let alone
suffer injury by one.

As others have mentioned, PA systems are different than consumer-grade
stuff. 70 volt audio lines etc.

In order for this to happen, tho, it probably required both a frayed
cord and a defect inside the amplifier.

While it isn't very common, over the years I've heard of about
half a dozen people getting killed by microphones. Usually in
the UK, with their higher mains voltages means that you have less
chance of survival (with some sort of line-microphone cord short).

If I recall correctly, some fairly famous rock vocalist was killed
on stage this way.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.