When I installed them one of them blew upon powering up. The retailer said we should go up to the next rating. I was a bit frustrated at the experience and didn't feel comfortable putting higher values in my expensive components. I felt these expensive fuses should be made to tighter tolerances than the cheap BUSS fuses I had been using. If I remember correctly, that was the actual argument that the dealer told me.
This is what is referred to as a lie. Obviously they are not manufactured to tighter tolerances, reasons already given.
So what are you left with:
- Fast blow marked as slow blow?
- Poor quality control?
- Up-marking the fuse, i.e. taking a 3A fuse and rating it 5A. Why would someone do that? Well that will make the fuse run hotter and will increase the fuse resistance. Bad thing right? Nope, More resistance in the AC line, and the noise will always drop a bit. Noticeable? Probably not. When the fuse gets hot, the resistance goes up a lot. Noticeable? ... who knows. But .. but .. but .. thermal modulation! Well you don't want thermal modulation for a speaker fuse in a speaker line. In a power line that will give you even more filtering.
Don't you wish the manufacturer had their products validated by a 3rd party lab? ... like any product that fulfills a safety function should be! Probably it is .... by the company that makes it for $0.10 ...