We often use an "extender" to be able to connect multiple plugs to the same socket in the wall. This is just a plug with a box having space to connect multiple plugs. At other times we may use an extension lead.
If we connect a load of high power equipment, it creates an overload which can even cause fire.
Heat is dissipated when there is resistance in the flow of current. Resistance also exists in wires but at a very small amount. When an overload occurs precisely what part of the whole setup dissipate such much heat that the extender or extension lead may catch fire?