When a short circuit occurs, the current is no longer traveling through the intended circuit, or part of the circuit (ie: a resitor) so the parts that require some sort of current limitation to maintain power dissipation are no longer protected so they get really hot and sometimes catch fire.
the basic short circuit is formed by lack of insulation , This insulation failure occurs due to, in most cases by heat generated by loose connections. Later , as explained already, the current takes a easier path due to short circuit, causing further increase in heat , turning into flame, even if the fuse blows.
the plastic material used in cheap wires, aggravates the fire causing a major fire accident.
Most people at homes or managements of major building don't care to periodically check the electrical installation for these weaknesses and help prevent accidents.
Finally, Vittakiran, it may not be proper to remove part of a post after it has been used and a reply is based on it.
the heat can de produced by having a wire that is not the proper gauge. a friend of mine replced a fuse in a battery charger, and the fuse was the increct size (the origonal fuse size was a 2A slow blow, he replaced it with a 3A slow blow) one of the diodes in the bridge rectafier cought fire instantly. there was probabl a bigger problem with the circuit, but we'll never know.
the heat can de produced by having a wire that is not the proper gauge. a friend of mine replced a fuse in a battery charger, and the fuse was the increct size (the origonal fuse size was a 2A slow blow, he replaced it with a 3A slow blow) one of the diodes in the bridge rectafier cought fire instantly. there was probabl a bigger problem with the circuit, but we'll never know.