I theorize the student was plugging into a hot
stage pin connector, judging by where the arc damage is, and maybe doing so with all the crooked, straining, wiggling, slipping, huffing and puffing that high schoolers often bring to that task, and that commonly enough results in an arc that could
nip whatever flesh is adjacent (because the straining and huffing and puffing) at the time.
So I’d replace the damaged pins and re-wire that
connector like Steve said, with correct strip length and ferrules. The fuzzy stuff n1ist notes just looks like standard issue
ETC stuff to me, which can get a little hairy looking. It’d be pretty unusual to find
asbestos inside a fiberglass
jacket on a S4jr, but I suppose one never knows…
And I’d do a mandatory, non-blamey (re)training for everyone doing this work, to include how best to mate every type of
connector in your facility (including
hand position and what motions work best), what a correct and incorrect connection looks like, how to get help if they need it so they don’t abandon a poor connection that might for instance have a gap big enough for an arc to jump out or a
safety cable to get in, and also how to do that particular task of a lamp check without that hazard arising. Buy a
stage pin lamp checker, or any
continuity tester. When you do really need to energize one like for a
bench focus,
plug into a switched
outlet or
power strip so nothing’s energized until connections are made, or at least mate the
stage pins first and then
plug the
Edison into
power; I think that’s considerably less risky, especially in student hands.
Sounds like the student is okay but appropriately spooked. Help her feel okay about it by working with her nonjudgementally to figure out exactly what causes may have been, and use this to teach some
safety to everyone.