PLEASE DO NOT USE THESE AS FUSES!!!!

[unclejed613]

for your consideration... fuses from the Twilight Zone.... i have seen examples of the following things used as replacements for blown fuses.... inspiration for this post came to me tonight as i opened a meter i bought a few years ago to replace the battery and found the previous owner had done one of these two things when he blew the 3x20mm fuse in the meter...

covering the fuse in aluminum foil is a bad idea... if you have a meter for instance where the measured current is more than the meter's shunt can handle, you can at the least oxidize the outer layer of the metal on the shunt and change the shunt resistance, making the current measurements inaccurate, or cause the shunt (or meter leads themselves more likely) to melt or burn.. if it's in something else, like an amplifier or subwoofer... all you will do is let out more smoke, and maybe set your house on fire...

this is a more dangerous fuse...

i had a friend, whose brother borrowed his car... his brother blew two fuses in the car's fusebox, and replaced them with these because they were metal, and the right size... on a trip to play a gig in New Hampshire, my friend was driving, and turned on whatever these fuses went to (headlights and windshield wipers), and a while later "BANG......... BANG!........" and the headlights and windshield wipers went out..... the fusebox was one of those under the dash near the steering wheel... good thing my friend wasn't "kneecapped" by these little "replacement fuses"...

 

[rjenkinsgb]

this is a more dangerous fuse...

Mythbusters did article on people using .22 rounds as fuses!
Definitely not a good idea.

And I've first-hand experience of someone using pieces of nails in place or high current fuses, Some years ago I was called to a breakdown, where the table on a vertical borer was blowing fuses if they tried to reverse it.
The electrical cabinet was so tall I had to use a ladder to get to the right area of the control gear. I asked them to start it so i could see what was happening & BANG! One of the contactors exploded right in front of me.

One of the table motor power contactors had a welded pole so when they hit reverse & the other contactor came in, it put a dead short across two phases.

It turned out they had progressively replaced all the fuses in line with the machine as it kept blowing them, from the motor ones in the machine itself through finally to the main power distribution board - with those done the day they called me..
All with whatever chunks of metal they could fit in the holders & literally chunks of 6" nails in the main power board.


A far more common one I've encountered is people replacing semiconductor rated "ultra rapid" fuses with general line fuses, after a fault has blown fuses on a thyristor drive.
It's often caused just by a carbon build-up on the brushgear to the point there is eventually a flashover. With the proper fuses, no real harm done - but with GL fuses the drive is cooked first, then the fuses blow due to shorted thyristors.

 

[schmitt trigger]

When consumer electronics used to have external fuse holders which allowed the end user to replace the fuses himself, one of the tests UL had was to replace it with the highest rated fuse that would fit, and then provoke a fault.

For the ubiquitous 3AG fuses, this could be as high as 30 amps.
The unit should not emit fire or create a hazardous situation.... I can't recall whether smoke emission was allowed or not.
Otherwise the product would not get UL certification.

Passing this test was such a hassle for the manufacturers, that eventually they decided to put the fuses inside and add that "Non-user serviceable parts" label.

Later this was "upgraded" by thermal fuses embedded within the power transformer's windings, such that when an overload occurred, the transformer would go open circuit.

 

[unclejed613]

The unit should not emit fire or create a hazardous situation.... I can't recall whether smoke emission was allowed or not.

here's the UL 94 standard for plastics (including circuit boards, and all other plastics used in electronics) https://web.rtpcompany.com/info/ul/ul94v012.htm there are other similar standards, such as the use of flameproof resistors in circuits most likely to fail catastrophically... this is a good reason to avoid counterfeit transistors too... because they do tend to burst into flames when they fail... spectacularly, and they burn long enough to cause a fire...

 

[dr pepper]

When I worked for the grid they had things like that unc, they called them explosive disconnects. On overhead cables if there was a massive overcurrent caused by a lightening strike or a short an explosive charge went off to forcibly disconnect the power.

 

[Nigel Goodwin]

When I worked for the grid they had things like that unc, they called them explosive disconnects. On overhead cables if there was a massive overcurrent caused by a lightening strike or a short an explosive charge went off to forcibly disconnect the power.

As I think I've mentioned before?, a couple of years ago a fairly large sub-station 'exploded' - taking out the building that part of it was in. For a month or two there were numbers of container sized generators scattered about the area, to provide power while it was rebuilt. When it was rebuilt, they didn't bother with a building, they just left the transformer (one of a number there) outside.

It was never explained what happened, or if they even knew, but apparently a week or so before there had been a breakin, with idiots trying to steal cabling - if they came back then the bodies were vaporised, as no traces were found.

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[dr pepper]

Yes some bad things like that happen.
Lightning strikes cause some fairly bad damage.

 

[unclejed613]

it could also have been a "terrorist squirrel"... https://cybersquirrel1.com/ it seems animals account for a lot of power grid accidents...

 

[dr pepper]

Yep had squirrel trouble, once had a transformer overheat, instead of cooling oil it was full of acorns!