For what purpose is a main disconnect switch installed in an electrical service?

A main disconnect switch is installed in an electrical service primarily to provide a means to isolate circuits. This switch allows for the entire electrical system or individual circuits to be safely disconnected from the power supply, which is crucial for maintenance, repairs, or emergency situations. By isolating the system, electricians can work without risk of electrocution or electrical fires caused by live circuits.

This functionality is especially important in ensuring safety, as it allows for the complete shutdown of power to an area so that repairs or inspections can be performed without risking injury. While other options address important aspects of electrical safety and system performance, the fundamental purpose of the main disconnect is to enable safe isolation of electrical circuits.