Purpose

• Both fuses and circuit breakers serve the same purpose, to create a weak point in the electrical circuit. If the circuit becomes overloaded, the fuse or circuit breaker will fail before the wiring overheats or fails somewhere else.
  
  

Fuses

• Fuses fulfill this role by containing a metal filament which melts at a lower temperature than copper wire. If the circuit becomes overloaded, this filament melts, breaking the circuit.
  
  

Circuit Breakers

• Circuit breakers contain a metallic strip which bends when heated, breaking the connection. This releases a spring-loaded switch which can be reset, restoring the circuit.
  
  

Difference

• The major difference between the two devices is that when a fuse blows, it must be replaced. Circuit breakers can simply be reset to restore service.
  
  

Safety

• Another important difference is that a circuit breaker always provides the same amount of protection, while you can significantly reduce the protection a fuse offers by selecting the wrong replacement. A fuse rated for too much current can allow the circuit to overload.