It is an occupational hazard receiving and electric shock to a spark and you should plan for it. Hence the use of thick rubber soles, being dry before working on an installation, and using fibre glass ladders. All of which I explain to trainees. I am not being cavalier about this it is just a fact of life it is not if it is when it will happen. Observing the above i.e. increasing resistance so that we become the biggest 10 million ohm resistor possible, reducing the risk when it does happen to the difference between fatal and a "belt" When working on three phase boards, not holding the door with one hand and the casing with another, things like that. Strategies that make a big difference in the event of shock.