Which of the following factors must be considered when applying any fuse?

When selecting and applying a fuse, it is crucial to consider factors such as voltage, continuous current-carrying capacity, and interrupting rating.

Voltage is important because the fuse must be rated for the circuit voltage to ensure that it can safely operate without failure. If a fuse is chosen with a voltage rating lower than the circuit voltage, it may not be able to withstand the voltage, leading to dangerous conditions, including potential overheating and failure.

The continuous current-carrying capacity is vital because a fuse must be able to handle the expected load without blowing under normal operating conditions. Selecting a fuse with insufficient current capacity can lead to nuisance trips, while one with excessive capacity may not provide adequate protection against overcurrent situations.

The interrupting rating indicates the maximum current that the fuse can interrupt safely without causing an explosion or fire. A fuse with too low an interrupting rating for the circuit conditions could still pose risks even when installed correctly.

Considering these factors ensures that the fuse will effectively protect the circuitry from overcurrents while maintaining safe operation, aligning with electrical code requirements and best practices in electrical installations.