This perception is a hold over 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
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.
Your 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.
We frequently get reports that our current-limiting fuses are still working fine forty or fifty years
after being installed.
There is no recommended replacement schedule for our fuses. When properly applied, they retain
their performance characteristics until they are called upon to interrupt an overcurrent event â€“
then they open and need replacing. We hope this gives you a clearer understanding of how fuses
operate and how the old perception of fuse fatigue developed.