Well, off the top of my head there's the demons Buffy kills in the sewer in "The I In Team", and... I think that's pretty much it. And both there and in this episode, it has a certain air of turning your enemy's weapon back on him. Electricity, like guns, is a somewhat non-Slayery concept. Personal demons Vampires are slain by hand or by dragging them into the light. (Adam feeds on electricity.)

There's probably meta in this. Different weapons for different monsters. In post-war Japan, electricity could kill Godzilla. In post-modern US, you poke monsters with sharp sticks.