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48 volts dc is standard telephone voltage, 90 volts AC gets you a ring. Most muni's around the country require a licensed electrician for anything overy 50 volts. What does this mean? It is normally the point people start taking power into serious consideration. Still, lot's of people think they are experts at things they know nothing about.

Now this is where it gets scary, and you have to have to have gut instinct as to the proper selection of contractors to hire...where it's not about money but credibility. Most trained electrician's are competent and credible, unfortunately we have a few that make lawyer jokes look like jokes about saints.

My gut feeling tells me there is a lot more here going on than meets the eye, but to be fair, I'd have to be part of the investigating team. My bet is that either it was wired wrong from the "last improvement" or was never rigth in the first place. Second place I'd be considering is the grounding. Just some educated guesses without being there.

Just spotted this ping. I have heard of this (what happened in the church) many times, but there is no one possible cause, there are a few.

48vdc is enough with the proper loop to stop a heart. It requires somewhere in excess of 20ma (milliampere) of current flow. So mic power on the older systems can do it. The newer ones use less juice, or powered mics.

The tank or pool would have been grounded through the plumbing or any device.

There is a second and more probable cause, and that is the tank heater. They frequently warm the water with a submersible warmer that is usually 220VAC. If is was still in place and in the tank, he would have grounded himself though the Mic which is attached to the amp chassis ground if it had metal parts in the handle. If the heating element was shorted, or miswired, he would have received a 120VAC shock directly through his chest, and if the mic was in the left hand, his heart would have been directly in the path. The left hand would be worse than the right, but both could kill.

The second situation is more likely than the first, but I don't know how old the PA was, or what sort of mic was used,. (electret condenser, or cartoid) are but two types and the voltages vary widely.