I was a mining electrician, trained in the UK worked in several mines there, coal, gypsum and potash, then tin and coal in Australia. It was rare to hear of shocks as it was illegal to expose live conductors to the air, more so in hazardous mines like coal.
I was a district electrician at a potash mine in north Yorks, UK, it was a "gassy" min so everything was either flameproof, (explosion proof) or Intrinsically safe. I got a call from an under cutting machine driver, who said he'd had a shock. Any reports like that are ALWAYS treated seriously. The machine was fed with 1100 volts via a trailing cable from what we called gate end boxes, switchgear, either a section switch or a contactor box, both with extensive safety circuits like monitoring of the earth continuity to the machine, earth fault protection, overload etc.
My first thoughts said impossible, but I still had to investigate. I found nothing wrong, everything was working correctly, nothing loose or shorting, all tests proved OK. I called my Foreman, and we went through everything together, nothing found.
So I asked the operator, a good friend of mine to show me exactly he was doing when he got the "shock"... Once he showed me the penny dropped. we used extension trailing cables joined with restrained flameproof couplers, the plugs were tightened in place by screw clevis pins, he lifted the coupler with both cable plugs, and dropped it. I reached down and tightened by clevis pins tight...What had happened was a 25 volt shock, hot conditions and very salty, combined with his sweat, made a good contact. The cutters were fed from a section switch, the earth continuity, (pilot circuit) was powered by 25 volts DC in what is called an intrinsically safe circuit, not enough energy to ignite methane. In ideal conditions he'd never have felt it. After tightening the plugs, he couldn't feel anything.
At the same mine I was called to the shaft bottom, the gate safety interlocks had failed locking the winding engine brakes on. One of the snap lock switches had failed from salt water corrosion. So I signed a new switch out from the stores. These too operated at 25 volts DC, take it from me it hurts when your hands are wet from dripping salt water!!