No of course it shouldn't glow under normal conditions! Even when overloaded for an extensive period of time it'll usually get just barely too hot to touch. They also have a ceramic body filled with sand so except for the metal end caps I've got a truly hard time imagining one glowing red hot all over.
If you're careful you can open the fuse without damaging the ceramic part and insert whatever wire you feel like so that's one possibility what might have happened in that video. Lunatics have also been known to mill their own no-blow Diazed shells from solid aluminium or brass so I suppose one of those could glow if there was truly a short on a beefy supply but I guess that would require a few thousand amps.
I've got no way of knowing this but I strongly suspect that the fuse wire in Diazed fuses up to 35 A is exactly the same stuff you can buy on cards for your old Wylex fuses in the UK. Larger ones might be more tricky, I definitely know that German HRC fuses (called NH fuses, short for low voltage high capacity fuses) have pretty complex flat conductors with holes inside instead of plain round wire - we're talking 100 A and up, I believe the pictures I've seen were a 160 A one. These fuses are designed for incoming mains and DNO wiring, i.e. any place where seriously high fault currents can be expected.
Next time you see a video like this just hit Ctrl-C and give us the link, we're all curious!
Post a link to the video, perhaps there is someone here who knows what language it is, or speaks it, or even knows someone who does. Wish my Grandfather was still around, spoke German, Russian, Polish,Yiddish. and a few others, & learned English when middle aged.
As I said, just copy the link from you browser's address bar and paste it into the post editor here! I probably wouldn't understand anything either because I don't happen to speak any Slav languages but taking a look would be interesting. I do know a few people who speak ll kinds of languages so finding someone shouldn't be too hard.
I have disassembled Neozed fuses and they had the flat conductor with holes punched in it down to 16 amps. All embedded into some kind of sand that helps extinguish the arc. I think the older Diazed dont have the holes. You can sometimes see the end of fuse conductor at the side of the metal end caps.
Btw, Siemens give a thermal loss of 1,7 Watts for a 32A neozed operating at full current.
Diazed fuses often have a flat strip of silver/copper in them with holes at certain locations to create a weak point set for the current the fuse supposed to operate at. The screw in bottle type fuse is often filled with fine quartz sand to ensure quenching of the arc. Those fuses can get very hot when running at full load and good clean and tight connections are a must. The DIN wedge type fuses are also build in a similar way and show the breaking capacity in kA's. Good HRC fuses are 80 or 120 kA rated.
The product of rotation, excitation and flux produces electricty.