Origanaly I posted this in the uk snow thread but as its a good clip I thought I would stick it here too. ENJOY. :twisted:

http://www.youtube.com/watch?v=slyRo5lMCPw

Great video Dave

What gets me with that with all the snow which must be electrically conductive how come it does not short out or eletricute anybody?

While water is conductive snow and ice are excellent insulators!  The arcing is caused by the juice "jumping" through the insulator and we were always taught never to look directly at it as it has the same effect as looking at somebody welding without eye protection.

You could always tell if it was a frosty morning before venturing out as the sky would be lit up by the trains arcing away!

If they got it wrong and the wheels slipped it was possible for the shoe to weld itself to the track! Happened when they used the switch from series to parallel - marked for used with Folkestone Harbour only!!! pre anti slip days.

The arcing is always spectacular!

Pure water is not conductive, only water with impurities conducts (and generally, conducts very well!!). Most of the water we know has impurities but, when frozen or boiled, loses those impurities to the surrounding medium - sea ice, for example, is not salty.