Thread: Fuses
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Old 29th Apr 2013, 2:16 pm   #40
Join Date: Oct 2005
Location: Olympia, Washington, USA.
Posts: 459
Default Re: Fuses

I had the voltage rating on fuses explained to me by the local supplier thusly:
The voltage rating on the fuse is the highest voltage that the fuse will take after it opens and not arc over.
So its fine to use a higher voltage rated fuse on lower voltage but not the reverse.

That being said, one must keep in mind that the $35.00 semiconductor will blow to protect the $.25 fuse.

Here in the States, the ceramic sand filled fuses are generally used in high heat applications, according to my distributor. Typical use for them here is in microwave ovens.

The voltage rating for a fuse is the max amount of voltage it will take before arcing across the opened fuse metal ends.
IE: A 32V car fuse, can be used on the mains voltage, but if it fails, the voltage can arc over the ends of the broken fuse ends.
If a fuse of a 250V rating is used, it is supposed to not arc till the voltage exceeds 250 V.

I have some big industrial fuses here that one can unscrew and one can replace the fusing wire element inside them when they blow. It can take a pretty good load to open a 1000 A fuse.
(Hopefully its not a "body resistance test" type load. I saw way too many examples of that working for the state labor & industries safety division in my youth.)
FrankB is offline