Protection devices—fuse versus circuit breaker What is the basic practical difference between a fuse and a circuit breaker in low-voltage protection?

Introduction / Context:
Overcurrent protection ensures wiring and equipment are not damaged by faults. Two common devices are fuses and circuit breakers. Knowing their distinctions helps technicians select, maintain, and reset protective devices safely and economically.

Given Data / Assumptions:

• Low-voltage distribution or electronics contexts.
• Normal definitions: a fuse melts once; a breaker trips and can be reset.

Concept / Approach:
A fuse contains a calibrated element that melts open under excessive current, providing a one-time interruption—replacement is required. A circuit breaker uses thermal-magnetic or electronic sensing to trip a mechanical switch that can be reset, restoring service after clearing the fault.

Step-by-Step Solution:

Verification / Alternative check:
Standards (e.g., IEC/UL) and manufacturer datasheets describe fuses with I^2t melting and single-use links; breakers specify trip curves and reset mechanisms.

Why Other Options Are Wrong:

• Fuse is slower: not generally true; high-rupturing-capacity fuses can be very fast.
• Fuse is reusable: false by definition.
• Breaker more reliable: depends on application and maintenance; not the “basic” difference.

Common Pitfalls:
Assuming one device is always superior; selection depends on fault levels, selectivity, and maintenance practices.

Final Answer:
A circuit breaker is reusable.