Final answer:
The two types of thermal overload devices are circuit breakers and fuses, both designed to protect against thermal hazards by interrupting excessive electrical currents.
Step-by-step explanation:
The two types of thermal overload devices designed to prevent electrical thermal hazards are circuit breakers and fuses. These devices are crucial in electrical safety systems to protect against excessive currents that can cause overheating and potentially result in fires or damage to electrical equipment. A circuit breaker is a switch that automatically interrupts electrical flow when the current exceeds a predetermined level, whereas a fuse contains a piece of wire that melts and breaks the circuit when overheating occurs due to overcurrent.