What is the difference between a service disconnect and a main breaker?

What is the difference between a service disconnect and a main breaker?

• A. The service disconnect is the point where the service can be disconnected; the main breaker is the primary overcurrent device for the service.
• B. The service disconnect is the point where the service meter is installed.
• C. The main breaker is used to disconnect only lighting circuits.
• D. They are always combined in a single device.

Answer: (A)

The service disconnect is the boundary device where you can shut off all power entering the building from the utility. It marks the point at which the electrical service becomes the property of the building owner and is the practical means to disconnect the entire service for maintenance or emergencies. The main breaker, located in the service panel, is the primary overcurrent protection device for the service conductors; it regulates and limits the current to protect the wiring and equipment, and it also serves as the main switch to disconnect power to all branch circuits when needed. In many setups these two functions are combined in one device, but conceptually they are distinct: a disconnect point vs the protective device.

The service disconnect is the boundary device where you can shut off all power entering the building from the utility. It marks the point at which the electrical service becomes the property of the building owner and is the practical means to disconnect the entire service for maintenance or emergencies. The main breaker, located in the service panel, is the primary overcurrent protection device for the service conductors; it regulates and limits the current to protect the wiring and equipment, and it also serves as the main switch to disconnect power to all branch circuits when needed. In many setups these two functions are combined in one device, but conceptually they are distinct: a disconnect point vs the protective device.