[howard941]

>I think it was Louis Rossmann who tested out some automotive fuses purchased from Amazon to see if the fuses were actually rated for what was printed on the label. I believe the fuses _failed to fail_ when running amperages higher than what was written on the fuses themselves.

Do you remember if he took his fuses' time-current curves into account? Fuses will generally pass more than their rating for some period of time, blowing faster if the current's significantly over the rating, slower (maybe much slower) if it's only a little bit over. By preventing nuisance blows it's considered a feature rather than a bug.

[Rygian]

https://www.youtube.com/watch?v=B90_SNNbcoU

[howard941]

At your link I saw that my point had been brought up in the comments. The 2 amp fuse passing 8 amps for minutes is for sure a problem. I'm not sure about those other fuses, they didn't seem to be far off. And there was a 2 amp fuse that blew at 4 amps after a few seconds which is what I'd expect. I didn't have enough patience to watch all 31 minutes of the video though, I was jumping around. In all fairness I think he proved his point.

[quickthrowman]

Here’s a trip curve chart of some Bussmann blade type automotive fuses for comparison: https://www.eaton.com/content/dam/eaton/products/electrical-...

[snypher]

Generally speaking automotive fuses are oversized for their circuit and should be of 'fast-blow' type