Branch circuits are primarily rated based on what criteria?

Branch circuits are primarily rated based on the overcurrent protective device rating. This is fundamental because the purpose of a branch circuit is to deliver electrical power to loads through conductors, while the overcurrent protective device (such as circuit breakers or fuses) serves to protect the circuit from overloads and short circuits. The rating of this device determines the maximum current that can safely pass through the circuit without causing overheating or damage, thereby ensuring safe operation.

While voltage level, wire size, and load type are important factors in the design and implementation of electrical systems, they do not primarily dictate the rating of branch circuits. Voltage level relates to the potential difference and may influence circuit components but does not serve as the main rating criterion for protection. Similarly, wire size is determined based on the load current and other factors, but it is the overcurrent protective device that ultimately establishes the circuit's safety rating. Load type may affect how circuits are designed and planned, yet the critical factor in protecting the circuit remains the rating of the overcurrent protective device.