The voltage rating of a fuse or circuit breaker must be equal to or less than the system voltage rating to ensure proper interruption. Is this statement true or false?

• A. True
• B. False
• C. Only for fuses
• D. Only for breakers

Answer: (B)

The key idea is that a fuse or circuit breaker must be able to safely interrupt the circuit at the system’s voltage. The voltage rating on these devices is the maximum voltage they are designed to withstand and interrupt without insulating break-down or arcing. If the device’s rating were lower than the system voltage, it could arc over or fail to interrupt properly when a fault occurs, which defeats the purpose of protection.

So the correct approach is to use a device whose voltage rating is equal to or greater than the system’s voltage. For example, on a 120V system you’d use a device rated at 120V or higher (such as 240V in some cases), not a device rated for a lower voltage like 60V. This ensures safe interruption under fault conditions.