The service disconnecting means need not be greater than 30A where there are not more than how many 2-wire branch circuits?

The correct answer is that the service disconnecting means need not be greater than 30A when there are not more than two 2-wire branch circuits. This is based on the National Electrical Code (NEC) guidelines, which allow for a certain level of load to be safely managed by a smaller disconnecting means when the number of branch circuits is limited.

When a building has two or fewer 2-wire branch circuits, the electrical load is relatively manageable, allowing for a lower amp rating on the service disconnect. This approach is designed to ensure safety while not exceeding capacity. As the number of branch circuits increases, the potential load also increases, necessitating a larger disconnect to prevent overload and ensure electrical safety.

In this context, if the number of branch circuits exceeds two, the capacity of the disconnecting means must correspondingly increase to handle the larger expected load. Thus, maintaining a limit of two circuits allows for a more flexible and efficient approach to electrical service design, while promoting safety and compliance with the NEC.