wrote:

On Monday, 19 March 2018 16:18:39 UTC, whisky-dave wrote:
On Monday, 19 March 2018 16:11:42 UTC, The Other Mike wrote:
On Mon, 19 Mar 2018 08:27:31 -0700 (PDT), whisky-dave
wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric
fire at a potential difference of 240v

Assuming you mean at the BS1363 plug then the fuse should be sized to
protect
the cable.
--

Nice, that's the sort of answer I'd expect :-)

But this was a question given to students doing our science foundation
course where they are expected to say 5 Amps. (a student has left their
marked paper (mid semester test) in the lab so I thought I'd have a
look).

5A is a better answer than 13. It would give added protection against a
partial short of the heating element. Either is compliant with BS. TBH
this is very basic stuff.

It depends on the heating elements temperature coefficient of
resistivity and how hot it gets. Some 1.15kW heaters may draw much
more than 5A for tens of seconds on starting.



I have also been told that H&S state that consumers/users should only
use either a 3A of 13 amp fuse in a plug and that is what we as
technicians have been told to use, even though I have loads of fuses
including 1A, 2A, 5A, 7A, 10A and 13A

complete cobblers of course.


https://www.rospa.com/home-safety/uk...icity/plugs-fu
ses/choosing-fuses/

a useful rule of thumb for folks that need to be told which fuse because
they have no idea. Such people normally only have 3 & 13A. That's all it
is.


NT


--

Roger Hayter