Multiwire branch circuits must supply loads that are:

Multiwire branch circuits are designed to utilize multiple phases of electrical power to supply a variety of loads. When discussing these circuits, it is crucial to understand their configuration and the nature of the loads they can effectively supply.

The correct answer indicates that multiwire branch circuits can provide power to only line-to-neutral loads. This is because multiwire branch circuits typically consist of two or more circuits sharing a common neutral conductor. When the loads connected to these circuits are line-to-neutral, they can distribute the electrical current effectively while ensuring that there is a balanced load on the neutral.

Using line-to-neutral loads helps prevent overloading of the neutral wire, as it can carry the return current from both lines involved in the multiwire setup. This ensures adherence to electrical safety standards and reduces the risk of overheating or electrical faults.

In contrast, loads that are line-to-line must use both phases of the circuit but do not require a return path through the neutral, which can create potential imbalances and hazards in a multiwire circuit configuration. Additionally, mixed loads introduce complexities in circuit balancing and can lead to compliance issues with electrical codes. Thus, focusing on line-to-neutral loads maintains system integrity and safety in multiwire branch circuits.