The transmission line circuit breakers trip just as it's starting to tilt, with those arc-overs as the cables get too close to the pylon. So after that point it's all mechanical. Thin sheet metal Faraday cages are moot, when it comes to tons of falling steel girders.
That said, after it gets hung up by cable tension, I would drive under it - for enough money.
As for building (slum) fire 'melting' steel - no, but it can get thin steel girders hot enough to go soft. And those pylon girders are thin. The important point being that their thinness prevents much heat loss by conduction from the section within flames, along the girder to cooler areas. Also the absence of fire insulation on the pylon girders, unlike the very good fire protection all steel frame skyscrapers have around the pillars
For what fire does to thin, unprotected, low thermal mass steel girders, I'm sure everyone has seen the twisted tangles of collapsed steel roof girders after fires in small factories.
Otoh, building fires cannot heat steel up enough to form rivers of bright yellow molten steel flowing out the window openings of a skyscraper. And yet there are multiple clear videos of this happening in a specific case.