Why does fog cause tripping of Transmission lines?

Transmission line trips due to fog. Transmission line towers, though designed per code provisions, may fail during mandatory testing required in many countries, which leads massive damage to power system. read more

All the insulators on the line are in parallel with each other.If the leakage in all of them combined is enough to trip the line,it will trip. in practice leakage will vary. If the sum for each is radically different, you can get a differential earth leakage trip rather than any other kind. read more

When a fog occurs, the air humidity is approaching 100% and condensation will tend to occur on surfaces exposed to the fog. The condensation will also occur on the insulators which are supporting the transmission lines, leading in some cases to voltage breakdown and tripping of circuit breakers. read more