Can Wet Electrics blow a man-hole cover off?....

You don't need any transformer for a big electrical fire. Of course a large transformer is filled with oil which can vaporize and then explode, but the pure electric power is good enough for a big show. The temperature of an electric arc this big is greater than the surface temperature of the sun!

Here's a trailer which had crashed into a switchboard cabinet:

Those cabinets run on 230V/400V rotary current (230V phase to ground and 400V phase to phase). The usual output of the transformers feeding many blocks are 50kA per phase. If the distance between the short circuit and the transformer is high enough, the small resistance of the feeder cables limit the current somewhat so it takes a long time to blow the fuses.


Here is an incident where a truck had crashed "briefly" into a small transformer. Those feed about 3 blocks of homes, are usually erected when a residential area outgrew a major transformer.
After the crash, the box had started to smoke and after a minute, an electric fire blew off the cover. Look how far it flew away! The transformer itself didn't blow up, this as just the blast from a massive electric arc.


A transformer which blows up looks like this:

The overload from the arc overheats the transformer. When the coolant oil of the transformer boils, safety valves vent the oil-steam which ignites in the arc and causes this huge oil vapor explosion.