🚀 go-pugleaf

"Peter Hucker" <none@spam.com> wrote in message 
news:op.uke2s5z24buhsv@fx62.mshome.net...
> On Mon, 10 Nov 2008 00:26:24 -0000, Dave Plowman (News) 
> <dave@davenoise.co.uk> wrote:
>
>> In article <EFJRk.52823$vm.21202@newsfe08.ams2>,
>>    Arfa Daily <arfa.daily@ntlworld.com> wrote:
>>> Well, the cable itself may be rated to 32 amps, and the breaker may be
>>> either 32 amps or 30 amps in an older installation, but never-the-less,
>>> this type of installation has always been known generically as a '30
>>> amp ring main circuit' and is generally accepted as being safely rated
>>> to 30 amps to include all ages of installation.
>>
>> Dates from the days of rewirable fuses were it was a nice round figure.
>> But with those you could comfortably exceed 30 amps if the load was
>> imposed gently.
>
> Some fuses are really rubbish.  I know of someone who ran a kettle for 3 
> weeks (under normal everyday use) on a 5A fuse before it blew.  The kettle 
> element was consuming its rated 10 amps.
>

Some peoples knowledge is really rubbish.

There are defined tables and graphs which accurately describe fusing 
capacity of fuses, it is known that a 5A fuse will carry 10A - but not for 
very long! If the kettle boils before the fuse wire works up to its melting 
temperature then the fuse wire cools again before it blows so you get away 
with it another day, but each time the fuse is used above its rated current 
it degrades a little and sooner or later will fail within the time it takes 
the kettle to boil.

Actually a 5A fuse carrying exactly 5A has a finite fife expectancy - which 
actually isn't all that long, unfortunately I can't find the graphs to look 
up the exact life expectancy.