Why do fuses just "blow"?

[Turdus]

Got a 2003 Panisonic 32" HDTV... old style.. tube, heavy, etc.

Worked great last night. No power this morning. Checked a few web sites, and one said to check the fuse. Sure as heck, it was blown. Replaced it, and TV works fine now.

Why would a fuse blow like that? It was on a surge protector, and I've never had any other problems with electronic devices.

Can a fuse wear out, and thus blow ?

[crunchee]

I used to think they'd wear out with normal use eventually, but then I found this:

http://www.cooperbussmann.com/pdf/2ed874bd...80f9399379e.pdf

I don't know how this applies to fuses for TVs...or for amplifiers, for that matter. I'm curious to know, too, especially since amp fuses in my Fenders are slow blow types, and they're old amps.

Edited to add: Now I'm wondering if 'overcurrent events' occur with normal usage, even with a surge protector.

[Brewmaster]

Sometimes an "over current event" is caused by internal issues, such as a cap or resistor failing, releasing a surge that trips the fuse. That is actually the main purpose of the fuse. A component fails due to age and extended exposure to heat. Replacing the fuse may work by itself but do expect it to happen again. When that component hits a certain temperature the same thing will happen. You have to find the failed component and replace it.

Fender amps are also designed to blow a fuse when there is no load on the OT, i.e. no speakers connected, to protect said OT.

[crunchee]

I wonder if cheaper fuses are made from Zinc, instead of Copper or Silver. My local Lowe's carries Bussman brand fuses but they're expensive. Radio Shack are much cheaper...but they're not Bussmans.

[Armitage]

I've asked a few guys around here, and all we can think is that one in a million chance (well one in 360 degree chance) when you turn on your amp you hit at the peak of the sine wave and get 160 volts and try to charge your caps... you can also lose a fuse with a surge... but we're all sticking to the fatigue thing. I've seen lots of glass fuses with the element all bent out of shape, but hasn't blown, and a fresh fuse looks like new when I look in next.

I just wanted to add, I never see larger fuses go without explanation, just the small glass ones, and we've literally got millions of fuses here, as they say, fuses protect people, breakers protect equipment, fuses are much faster (generally).