Final answer:
Fires in homeless shelters can be caused by overloaded extension cords, unattended or prohibited microwaves, and halogen lamps, all of which create thermal hazards by generating excessive heat or electrical currents that can ignite a fire.
Step-by-step explanation:
Typical causes of fires in homeless shelters include factors such as overloaded extension cords, unattended or prohibited microwaves, and halogen lamps. These items can cause excessive electric currents and consequent undesired thermal effects, leading to fires. Overloaded extension cords, in particular, exceed the rated maximum current that the wires and appliances can handle, leading to overheating and potential ignition. Unattended microwaves can also start fires due to electrical faults or by heating items that shouldn't be microwaved.
Halogen lamps generate high amounts of heat and can easily ignite nearby flammable materials if they are placed too close or if they tip over. All these situations create thermal hazards, which is a condition where electricity causes undesirable heating effects, capable of starting a fire. It's important for shelters to have safeguards like fuses and circuit breakers to prevent such hazards.