What’s so dangerous about high voltage?

By Marcus Wilson 24/02/2010

There was a short piece on the television news last night about the ‘Taser’ weapon now being used by the NZ police force.  I always listen carefully to popular media when they discuss electrical things, since there is a quagmire of terminology that is often used incorrectly.   This time, however, I didn’t pick-up incorrectly used terms – "50 thousand volts" was mentioned, but fortunately not in the context of 50 thousand volts of current, or 50 thousand volts flowing through it, or a power of 50 thousand volts.  Well done TVNZ.

One gripe though, the fact that it is 50 000 volts is only half of the issue. A Van der Graaf generator, as loved by all teachers of physics, (especially those with long hair) will happily get to hundreds of thousands of volts and pose no threat to anyone, other than the odd ‘zap’ that you wish to inflict on your students.  The point is that the current delivered by a Van der Graaf generator is tiny. Contrast that with the mains supply. It’s only 230 volts, but is designed to deliver large quantities of current.  That’s fine if the device on the end is your electric kettle or heat pump, but if it’s you then you could be in trouble – much more so than getting a controlled shock from a taser.  (Not that I would volunteer to experience the latter.)

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