Wear eye protection. Wear at least one rubber glove, unless you
trust yourself to adhere to the one-hand rule.
Start with a piece of stranded wire 4 or 5 cm long.
Unravel it to obtain the individual strands, thinner than a human hair.
Bring in an automotive battery charger.
Set it on the "50 amp quick start" range.
Use it to zap the little wires.
The following assumes that one end of the wire is already connected, and
we are about to connect to the other end:
*) I observe that if you approach the wire end-on you get a bright spark
and the wire gets slightly shorter.
*) OTOH if you approach sideways, you can create a situation where the
whole wire just disappears. I assume this is because you were better
able to establish solid contact all at once.
This makes the point that high voltage is not needed to make rather
impressive sparks. People have the misconception that sparks are
associated with high voltage, perhaps because you need a high voltage
to strike an arc through /air/ ... but this experiment shows that if
you've got a big current through a small area, it will quite nicely
melt and/or vaporize metal.
If I am doing the work, I don't mind doing it without gloves, but
if students are doing it I might require them to wear at least one
glove. I've never actually seen anybody grab the un-insulated part
of the aligator clip, and after seeing how violent the sparks are,
some of them may not want to go near the insulated part, either.
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As a refinement, I find it convenient to put a dab of solder on the
stranded wire before unraveling it, so that the result is a brush
rather than a pile of little wires. Then I can hook up one solid
connection to the soldered end, and then zap the strands one by one.
The advantage is that this involves making N+1 connections rather
than 2N connections.
Also I find _combing_ to be quicker than trying to unwind the strands
one by one.