Excellent high-voltage warning glyph

I'm having a pretty great time in Vancouver this week on the Pirate Cinema tour. Granville Island has lots to recommend about it, but I'm especially taken with the electrocution hazard glyphs on the access-plates set into the sidewalk. They even beat the lightning bolts that leap out of electric risers on the streets of San Francisco. What is it about the Pacific Northwest and awesome high-voltage signs, anyway? It's like this is some kind of lost valley where the coelacanth ancestors of Reddy Kilowatt never went extinct.

Electrocution warning icon, market, Granville Island (Vancouver Writers Festival), Vancouver, British Colombia, Canada