Every safety poster tells you never to put water on an electrical fire. Watch a fireground crew do exactly that, whipping the nozzle side to side, and the reason lives in the geometry of the stream rather than the chemistry of the water. Pure water is nearly an insulator — deionised water resists current at the megaohm scale. What leaves a hydrant is not pure. Dissolved iron, calcium and chloride ions turn it into a modest conductor, and a solid, unbroken stream aimed at energised equipment becomes a continuous wire back to the nozzle team. What decides whether that hurts you is current, not voltage. Perception starts near 1 mA; the muscles that let you release a grip lock up somewhere past 10 mA. The defence is to destroy the continuity of that conductor: - A fog pattern shatters the jet into droplets separated by air. Charge can no longer run along an unbroken column — it must arc gap to gap, and every air space piles on resistance. A 30-degree cone is the recommended attack patte...