What is a typical consequence if a fuse rating is set too high relative to the wiring ampacity?

What is a typical consequence if a fuse rating is set too high relative to the wiring ampacity?

• A. It may allow excessive current through the wiring before a fault is detected.
• B. It prevents faults from occurring at all.
• C. It reduces system voltage.
• D. It makes maintenance more difficult.

Answer: (A)

Fuses protect wiring by opening the circuit when current exceeds what the conductor can safely handle. The wiring has an ampacity rating, the maximum current it can carry without overheating. The fuse should trip before the wire overheats. If the fuse rating is set too high relative to the wiring ampacity, the fuse won’t blow until the current is already well above what the wire can safely carry. In a fault, that allows excessive current to flow through the wiring, heating and possibly damaging insulation or starting a fire before the fuse clears the fault. So the typical consequence is that excessive current can pass through the wiring before the fault is detected.

Fuses protect wiring by opening the circuit when current exceeds what the conductor can safely handle. The wiring has an ampacity rating, the maximum current it can carry without overheating. The fuse should trip before the wire overheats. If the fuse rating is set too high relative to the wiring ampacity, the fuse won’t blow until the current is already well above what the wire can safely carry. In a fault, that allows excessive current to flow through the wiring, heating and possibly damaging insulation or starting a fire before the fuse clears the fault. So the typical consequence is that excessive current can pass through the wiring before the fault is detected.