[lnsru]

In addition to other things I am certified electrician in Germany. Your claims are wildly oversimplified. Every fuse has a type, rating and trip current. I pick them by planned application, installation type and cable length. Copper cables cost money, the safety margin is THE fuse. Otherwise cable insulation gets too hot and wears too fast.

[blagie]

Is English your native language? You might be confusing fuses with breakers.

Fuses aren't typically used to protect copper runs; breakers are. Fuses are used inside of electronics. Breakers are rated as you describe, to protect copper runs.

For fuses, this is a data sheet of a random fuse (first one on Digikey search; I didn't pick anything special):

https://www.vishay.com/docs/28747/mfuserie.pdf

[lnsru]

The fuses are used in older installations. 25 A 500 V rated fuses are absolutely normal parts. They are usually slower than breakers. Breakers came later. The “normal electrician’s” fuses: https://ep-us.mersen.com/sites/mersen_us/files/2018-11/TM-10...

[blagie]

FYI: Page 6 is worth looking at.

* A 25A fuse will conduct 52A-110A for 5-10 seconds, which is about the 2x in my original post.

* For shorter time periods, this goes up a lot (150-260A for 100 milliseconds).

I'm getting down-voted, but no one is posting contradictory information. This discussion feels more like reddit than HN.

As a footnote, at least in the US, in the 21st century, I've never seen a house with fuses rather than breakers. As you point out, copper is expensive, and a breaker is $10-$15. It's not only more convenient, but saves more money elsewhere.

[rightbyte]

In many houses porcelain fuses are still in use instead of breakers.