Part of my normal work duties include ac dielectric testing up to 80kv. The procedures used determine how safe you are. I have an old Biddle with the hand crank & a modern fluke megaohm meter for home use. The instruction manuals for these include procedures for their safe use. Most important is not to come into contact with the specimen under test & to lower the voltage back to zero. Danger exists if test is interrupted, by failure or the operator, as cables, bus bars, arrestors, capacitors, can store energy.