Review on UCTRONICS Values Fast Blow Assorted Plastic Industrial Electrical and Circuit Protection Products by David Bowens

In November 2018 I was looking for a 15A 5x20 fuse to replace a blown fuse in my cappuccino maker. I put the first one on deflated after a few weeks, which didn't bother me at all. This indicated that it was working. The second took longer, but mainly because I rarely use this cappuccino. In November 2020 the fuse blew again. This time I had a hard time getting the fuse holder out. It turned out that the heat generated by the fuse had melted the plastic fuse holder that was bonded to the plastic case around it. See photo. It's hard to imagine that a fast-acting fuse could instantaneously give off enough heat to melt plastic so badly. It is more likely that the fuse has blown and acts like a heating element every time a large current flows through it. A box of 150 fuses isn't used unless you know which ones work and which ones might fail. The only way to test a fuse is to run a lot of current through it and see if it blows. But as soon as I do that, the fuse blows and becomes unusable. If anyone has a better way of verifying this, please reply with a comment. Until then, I can't trust anyone in this whole fused aluminum box. Use them at your own risk.