Safety of Villard cascade
Getting shocked is good. Dropping solder on clothing and skin is good. Nicking the fingers on sharp metal edges is good. Humans survive by exploring. Humans learn from pain. Otherwise we'll be cowering in the swamps.

As a kid, I felt 117 VAC tingles through the toes, from old power transformers. I learned to sit on wooden chairs and not touch the toes to the concrete floor.

Later while "calibrating" an oscilloscope, I pushed the bared-back of the scope against the metal lab bench, touching the EICO scope tube socket to the bench, and then leaned forward with tummy against the front part of bench through my shirt, and touched my chest again through the shirt to the scope chassis as I reached far around to adjust a "focus" potentiometer. 3,000 volts across the chest. I sat, stunned, for a couple minutes.

But I had a few more lesson about high voltage still to learn.

Let your son see some high-voltage-death videos. 

Teach him the "keep one hand in pocket" trick around high voltage.

EDIT: Then there is high current; college prof told of buddy who lost the left ring finger, because the wedding ring ended up in a high current path, making the ring glow red, killing the skin, the muscle, tendons, and the bone.

I've also had MOSFET gate driver ICs blow off the top of the package, during the "bipolar snapback" event when the 1,000 μF storage capacitors inside a huge HP lab supply had the need to unload their energy into the 2 mm × 4 mm silicon of the gate driver. None of us three, hovering quite close, were hit. But after that, I always placed a sheet of paper atop the circuit, to intercept any more IC energy dumps. Energy? 1/2 * C * V^2 = 0.5 * 1,000uf assumed (did not open the HP supply) * 20v * 20v = 200 milliJoules which explains why the DIP plastic top was blown off. And missed our 6 eyes (tho I wore glasses).

EDIT: The gate driver blow-top-off was serendipity, because I took the lesson to heart and realized the danger of stored-energy in 1,000 μF caps. I learned how to tease-the-dragon in evaluating bipolar-snapback, allowing only 1,000 pF right across the Gate Driver, with 220 Ω resistor to the (experimentally variable) Vdd. Using a long-leaded 1,000 pF (3″ leads, 6″ total, or 100 nanohenry) along with the external 1,000 pF and the on-chip well-substrate of ~1,000 pF, during switching events the silicon VDD_GND would collapse and then rebound 5 or 10 or 15 volts above the rated 18 volts. At some level, the slewrate of the ringing (100 nH and 500 pF rings at 22 MHz) induced enough transient charge into the silicon that bipolar-snapback occurred, and the VDD (supplied by 1,000 pF) would be sucked down to 16 or 17 volts whereupon the snapback would self-extinguish.
I ran these devices, in/out of snapback at 100 kHz, with no damage, as I diagnosed the transient charge path and realized the layout rules needed change.
Serendipity. Energy? 0.5 * C * V^2 = 0.5 * {total protoboard + silicon Cap = 2,000pF} * 31.6volts^2 = 1,000pF * 1,000 (volts^2) = 1microJoule.

Decades back, returning from lunch, was told to go to lab and examine "the debris" on XXXX's bench. There was 6panel wirewrap board (30*6=180 ICs), many ICs with their tops blown off. Turns out a hanging one-end-loose wire had curled over and around and under the front bench edge and **INTO* the hot contact of 117VAC power. Thus management wanted all engineers and techs and rework folk to understand the danger of springy-curly wirewrap wires left hanging.

Ahhhh Assigned to 400-watt Tritek switching supply for couple weeks, for some reason. Just to give me experience in switchers; I was not the designer. Repeatedly, the sacrificial 5-watt 5 ohm wirewound protection resistors --- were exploded, their ceramic cores blasted out of the heatsinkable case and across the walkway between benches, the resistive wire trailing behind like guidance wire for a TOW missile. We learned to not stand in the way.

For safety, and no hum in highgain amplifiers (100dB and 120dB), I learned to use the 9volt "B" 3" by 3" by 4" batteries. The high Rout caused oscillations, almost all the time, until I learned to implement "local batteries" with RC LPF in the VDD to LNA stages. Quite a collection of 5,000uF caps I had.