Circuit Breakers and Fuses 101

Circuit Breakers and Fuses
Circuit breakers usually have two types of protection – thermal and magnetic. Thermal strips measure heat build-up caused by overloading. When it reaches a certain temperature, it shuts the breaker down. Magnetic coils measure increases in current, like a short. A predetermined limit will will shut the breaker off, when reached. Older breakers sometimes have only one of these features. For maximum protection, a breaker with both protections is recommended.

  • Some things to look for in a worn or problematic break include:
  • “ON/OFF” switch has broken off or loose, replacement may be required
  • If the load lug is burnt or abnormally loose, replacement may be in order
  • The breaker stab makes contact with the bussing in the panel (bussing carries power throughout a panel). The stab connects the bussing through friction and spring tension. Over time this may break down and arcing or burning may result. If the stab is burnt, discolored, abnormally loose, we recommend breaker replacement and checking the bussing in the panel.