For an installation consisting of not more than two 2-wire branch circuits, the service disconnecting means shall have a rating of not less than ___ amperes.

In the context of electrical installations, the service disconnecting means must be adequately rated to handle the load it serves. For an installation consisting of not more than two 2-wire branch circuits, the National Electrical Code (NEC) specifies that the service disconnecting means must have a minimum rating of 30 amperes. This requirement ensures there is enough capacity to safely handle the combined load of the circuits and to provide an adequate level of safety for the electrical system.

Selecting 30 amperes as the minimum rating provides flexibility in circuit loading and the potential addition of various appliances or devices that may draw power. It maintains safety standards by ensuring the disconnecting means can handle unexpected surges or preventive needs for power interruption.

Understanding this requirement emphasizes the importance of adhering to NEC guidelines to ensure safety and compliance in electrical installations.