Some of the common causes of thermal burns include:
Not using protective mesh or covers over lights
Allowing the reptile to lie directly on the heat cord or mat without having any barrier (i.e., a rock or tile) between the heat source and the reptile
Heat caves malfunctioning
Uneven heating of mats, cords, heat rocks or caves
Water damage
To narrow a basking area creating intense hot spot (e.g. overhead heat source too close to the reptile)
Not using a thermostat in the cage. Thermostats work by turning off the heat source once a specific temperature is achieved. Thermostats are recommended for all reptile cages with artificial heating.