Final answer:
Branch circuits supplying power to electric space heaters are typically protected by either 15-amp or 20-amp circuit breakers, limiting continuous use to 80% of the circuit's rated capacity for safety, which translates to 1,440 watts for a 15-amp circuit and 1,920 watts for a 20-amp circuit.
Step-by-step explanation:
The ampacity ratings for branch circuits supplying power to electric space heaters depend on the space heater's power requirements and safety regulations. Most electrical appliances, including space heaters, are rated in amperes, which determine the size of the fuse or circuit breaker needed to operate safely. For instance, a 15-amp circuit breaker is typically used to protect circuits supplying power to heating appliances like space heaters. Safety regulations often limit continuous use to only 80% of the circuit breaker's rated capacity. For a 15-amp breaker, this would be 120 volts x 15 amps x 0.80 = 1,440 watts, while a 20-amp breaker would allow up to 1,920 watts.
This consideration ensures that the circuit is not overloaded, which can be a fire hazard or cause damage to appliances and circuitry. For example, a 1500-W space heater is suitable for a circuit rated for 15 amps since it falls within the 80% safety margin. However, the cumulative power consumption of all appliances on the same circuit must be taken into account to avoid tripping the breaker. It's important to consider the total power rating of all devices connected to a single branch circuit and ensure that their combined power does not exceed the breaker's safe operating limit.