Final answer:
30 amp branch circuits commonly supply heavy-duty appliances such as air conditioning units and electric water heaters, and they are designed to handle substantial electrical loads with safety devices like circuit breakers and GFCIs for protection.
Step-by-step explanation:
30 amp branch circuits typically supply power to heavy-duty appliances and equipment that require substantial electricity to operate. Examples of such equipment include air conditioning units, electric water heaters, and some power tools used in garages or workshops. These circuits are designed to handle appliances that draw a significant amount of current, usually up to 80% of the 30 amp capacity continuously. This translates to a maximum of 5760 watts at 120 volts. Circuit breakers and fuses rated at 30 amps are employed in these circuits to interrupt excessive currents and to prevent thermal hazards, thereby ensuring both the safety of individuals and the protection of the equipment. Safety devices such as the three-wire system and ground fault circuit interrupters (GFCIs) are also commonly used in conjunction with these circuits to provide additional protection against shock and thermal hazards.