I saw a video on YouTube where it shows a diazed fuse actually glowing hot its described as resistance wire fuse surely they dontt use resistance wire in normal use is it just a video pranks?

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!

I will do that I couldn't tell you what the video was called because its in some east European language so is a bit beyond me like most brits I only speak english I know its wrong but thats how it is

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.

Is this what we've been talking about?

https://www.youtube.com/watch?v=3ugxq0FMjoQ

Hi Texas Ranger no thats not the video but that was the one that I talked about in my post short circuit? Which I posted last year sometime (I think) whatever its a cool video tho.

Oh dear ive been a silly girl my post I mentioned called short circuit? Wasn't posted on here but on a different forum so for the confusion

I'm left with the impression Russia can be rather boring.....?



~S~

I'm left thinking Russian electrics are a bit scary!!

Well if you deliberately overload them and possibly even bypass fuses any electrics get scary. Mix in some seriously dodgy DIY wiring and you'll end up with an explosive mix in just about any country. I've seen some seriously ancient and questionnable wiring in Northern Ireland, not so much in England yet, at least not in person. If you have a look over at DIYnot forums (electrics UK) you'll find a few hot messes rather quickly.

I'm not all that familiar with Russia but the house in the video definitely feels like extreme rural poverty to me and a setting like that usually breeds the worst wiring (and other building details). They do mention that there are no neighbours so I guess this is pretty remote.

I just checked out the video via the above link. All I can say is "MAD". Didn't see any science.

BTW, over on this side of the pond, I occasionally come upon the 1/2" or 3/4" copper pipe in fused disconnects for HVAC units. I posted a few pics over the years here.

Typical ways of bypassing Diazed fuses are wire (individual strands) wrapped around the ceramic body or a nail driven through the metal end caps and ceramic body. The worst kind is usually found in metal shops with a lathe, a solid metal bottle "fuse".

I've been guilty of "repairing" a 20 amp fuse myself, although I knew it only fed a single motor with additional protection of a 25 amp MCB upstream. The MCB was the actual protection for the old motor, the fuse was only necessary to avoid changing the historic wiring (ca.-1920) for a quick test run. Doing that I discovered that a single strand from a 1,5 mm2 conductor probably takes around 16 amps, maybe a bit less - it blew within less than a minute. A second strand fixed that issue. The next time we ran the motor we fitted a proper fuse of course.

I suspect perhaps this is the video we're looking for?

https://www.youtube.com/watch?v=T20ieVDAtrg

Yes thats it thats the video I was on about

Aaah, I think I know what's going on! Looks like a very bad overload, close to a short, and the fuse glows for a brief period of time before it blows (it does, right at the end of the video). The resistive wire is probably the load, not what's inside the fuse!
I've been told that these fuses can change as they age and should be replaced every 15 years or something - maybe that's why this one actually starts to glow before it blows?

BTW, the language is Czech. Not that understanding Czech would help much, they don't really talk a lot.

I've seen a few of those guys' videos before and they're absolutely terrifyingly dangerous, including playing around with unshielded magnetrons and so on. As far as I can figure out, they're in the area of Ukraine where the Crimea conflict happened a few years ago. One of their videos is about going to a bloggers' conference in Moscow and you would really feel for them. They're living a rather frugal existence and had to basically hitch hike to Moscow. It's a rather stark look into life in what is basically a very isolated and impoverished place where health and safety rules are the least of their concerns I suspect.

The last video doesn't look Ukrainian to me, the title is Czech and so is the warning label above the fuses. Apart from being aluminium and usually TN-C, older Czech wiring is usually surprisingly decent, plenty of circuits and healthily-sized wires (1.5 mm2 copper/2.5 mm2 Al for 10 A lighting circuits, 2.5 Cu or 4 Al for 16 A socket circuits). A while ago I posted pictures from an 1890s flat in Prague, rewired in the 70s I guess. IIRC the 1-bedroom place (kitchen, hall, sitting room, bedroom, bathroom) had two lighting circuits, two socket circuits, even a dedicated circuit for the extractor fan in the bathroom!

By comparison, yesterday I did some work in a very similar place in Vienna, rewired in 1969 and that had two general-purpose circuits and one oven circuit - period. The oven on a 10 A Diazed fuse wasn't such a bright idea, the base was completely burned! I only replaced a few light switches, once the place is cleared out the landlord will surely have it completely rewired.

I have learned that a 1.5 mm^2 rubber cable has 27 strands, and one is pretty equal to 5 amp fuse wire, the 2 is a little less than 10, 3 strands around 13 Amps. Never tested that on a diazed fuse, but on 12V systems, learned this when I asked about the UK rewindable fuse system my teacher told me this 35 years ago.

dsk

@Texas_Ranger : I was referring to a video further back up the thread with the ludicrously dangerous electrical 'stunts'. They were connecting wires as a resistance directly to an unfused mains supply at a meter etc.. Really insane stuff. If you've seen the rest of their videos, you'd wonder how they even are still around and they're certainly likely to be risking things like eye injury from UV from arcs and even microwave exposure from removing magnetrons from microwave ovens - high risk of cataracts and so on, if not serious burns.

Ah, I think you're talking about these two chaps!

https://www.youtube.com/watch?v=3ugxq0FMjoQ

When I was at highschool the GFCI's was introduced, and we could get extension cords with one. I asked a teacher on th Electro line (Education of electricians) if should buy one, and he replied:
T: Have you got electric shock?
Me: Yes
T: Did you get hurt?
Me: No!
T: Then you cope with it!

I bought one

dsk