Do fuses wear out over time? Do fuses need to be replaced?

The perception of fuse fatigue is a holdover from years ago when fuses were commonly constructed using zinc fuse elements. Zinc has a relatively low melting temperature and a high expansion coefficient. Through repeated circuit energizing and de-energizing, the zinc elements would heat up and cool down (expand and contract), causing them to fatigue over time and lower their current carrying capacity. 

New fuses utilize copper and silver for improved performance

This is NOT the case with modern, current-limiting fuses that are made with either silver or copper fuse elements. These have a higher melting temperature than zinc and are not typically susceptible to fatiguing over time.

Modern, current-limiting fuses should retain their performance characteristics for the life of the installation under normal operating conditions and proper sizing methods for the application. Eaton frequently get reports that Bussmann series current-limiting fuses are still working forty or fifty years after being installed.

There is no recommended replacement schedule for Bussmann series fuses. When properly applied, they retain their performance characteristics until they are called upon to interrupt an overcurrent event – then they open and need replacing.

In summary, the old perception of fuse fatigue was developed many years ago when fuses were constructed with zinc fuse elements and does not have much impact on modern fuse operation. 

If you have any questions about this information or about overcurrent protection in general, please contact us at FuseTech@Eaton.com.