“Don’t try this at home”
These kids need a mentor or classes to apply their enthusiasm more safely. Note the more safely part, as working on high voltage DC or AC requires a buddy system just as in professional diving.
A Jacob’s Ladder needs enough voltage to carry an arc with several inches of separation before re-striking lower upon the “V” formed by the conductors. It will happily jump through a person to reach grounding through concrete.
All true, I used a neon sign transformer that put out 9000 volts but only a few ma. But I also had a ham radio license and knew what I was doing.