It is not uncommon for lightning to strike electrical power equipment
(power lines, transformers, etc.). When this happens, many times the
lightning will cause a secondary arc. These arcs are usually referred to
as power flashes.
These power flashes are extremely bright and can easily light up the night
They can flicker like lightning, or glow for a second or two before the
circuit breakers trip and turn off power to the line (see video clip below).
Video clip of lightning-triggered flashover
Windows Media, 157KB
To see a more detailed description on how lightning causes electrical arcs or flashovers see our article about flashovers.