My understanding is that 50-60VDC is approximately the voltage at which electricity will arc through a person's chest (i.e. pass through their heart) if they ho

My understanding is that 50-60VDC is approximately the voltage at which electricity will arc through a person's chest (i.e. pass through their heart) if they hold a wire in each hand. That makes it unsafe to handle without special insulating equipment. That doesn't mean that 48V is safe necessarily though. If your hand is wet or even just a little sweaty, you can arc from pinky to thumb at ~48V.