Subject: Re: 125 or 250V fuse?
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Date: Fri, 27 Sep 2002 12:48:46 -0400
NNTP-Posting-Date: Fri, 27 Sep 2002 12:48:25 EDT
Organization: Bell Sympatico
Interrupting capacity. As Sam pointed out, 125 and 250 volt little fuses are
identical; that is mostly because it would cost more for the fuse maker have
different production lines than to stamp a lower - and safer - rating on a
given class of fuses, while retainting a full line of specific voltages in
In order to obtain UL (or CE or CSA) certification, manufacturers have to
provide spec sheets and undergo product testing. One of these tests is
critical for safety for any fusible element or circuit breaker: its
interrupting capacity. This rating is a direct function of voltage and can
vary from a few amps to several hundred thousands amps, for the power
distribution circuits. In practice, this means that during a fault, the
instanteneous current available may be so great that an arc could develop
across the fuse's terminal, even though its element has melted.
This has very little chance of happening in small electronic cicuits such as
yours; nevertheless, it has to be taken into account in some situations
(large amount of current can be obtained from electrolytics, for example).
You can get a lot more info from Littlefuse's "Fuseology" document, complete
with fuse facts and standards; its a 12 page PDF available at:
"KILOWATT" a écrit dans le message de news:
> Say two ¼ X1¼ AGC fast acting fuses.
> One is labeled 2A 125V and the other
> is 2A 250V. What should motivate me to
> choose a particular one for my project/repair
> in this case?
> Alain (alias:Kilowatt) Montreal Quebec
> P.S: Excuse me for some errors or omissions,since
> I'm a «pure» French Canadian :-)
> If replying also by e-mail,remove"no spam"
> (with the quotes) from my adress...thanks!
> Come to visit me @: http://kilowatt.camarades.com