How To Know the Difference Between a Fuse and a Circuit Breaker

Fuses and circuit breakers can both serve important roles in managing an electrical system and keeping you safe. Learn how to tell the difference between them.


  • Step 1: Know that the one advantage of using fuses is that they are cheap and widely available. Disadvantages of using fuses, other than the safety concerns, include the inconvenience of having to replace them when they blow and the difficulty changing them in the dark. Now you can address your electrical problems, with this knowledge.
  • FACT: The current running through the New York subway system's notorious "third rail" was diminished significantly in 1902 with the installation of circuit breakers.
  • Step 2: Know that the safety advantage for circuit breakers is that they always trip at the same level of current; fuses leave room for human error. If a fuse is replaced with the wrong type, the level of current allowed by the fuse changes, potentially allowing for too much current and starting an electrical fire.
  • Step 3: Understand circuit breakers, which are switches that trip when a circuit is overloaded. Unlike fuses, circuit breakers don't need to be replaced when they're blown -- you need only to reset the switch.
  • Step 4: Know three basic types of fuses -- time delay or TL, fast-acting, and very fast-acting fuses. TL fuses are medium-duty and are recommended for home use. Fast-acting fuses are heavy-duty and are used for devices on circuits that cycle on and off frequently, like sump pumps.
  • TIP: TL fuses allow a temporary rush of current to go through the circuit without breaking it open.
  • Step 5: Learn about fuses. Fuses plug or screw into a central fuse box. They contain a metal filament through which electricity must pass to complete a circuit; the filament will burn and melt when the fuse blows.

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