What is a service entrance in the context of electrical systems?

A service entrance refers to the critical point at which the utility's service conductors, which deliver electricity from the power company, connect to the electrical system of a building. This connection is essential because it marks the transition from external utility power to the internal wiring system that distributes electricity throughout the premises.

This point typically includes components such as the meter which measures electricity usage, a main disconnect or circuit breaker, and other equipment necessary for service entrance. Proper installation and adherence to relevant codes at the service entrance are fundamental for safety and operational efficiency of the electrical system.

The other options represent different aspects of an electrical system but do not accurately define the service entrance. While the main circuit breaker panel is an important component, it is not synonymous with the service entrance itself. The entrance point for appliances is a mischaracterization, as appliances connect further along in the circuit, not at the service entrance. The protective enclosure for electrical meters is a physical feature related to the service entrance but does not encapsulate the broader definition of what a service entrance actually entails.