power cables of 630 mm buried (cable trench) what could be the reason for fire?
A very high power surgeon could cause it. Very high current transfer of a short circuit could cause burning of the cable. Power cables have materials which have very high resistance (rubber materials mostly) but could burn in a not very high temperature.
a power surge can definitely cause a cable fire. but i believe insulation failure tops that, in buried cables in particular. and insulation failure is prompted more often with cables that come in direct contact with the earth, rather than those that may be run through piping, deterioting the insulation even faster. of course if the cable is damaged by digging, that could start a fire as well.
