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Posted to uk.d-i-y
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Fuse calculation
In article ,
writes:
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.
A 5A fuse passing 4A will give off 0.64W, generating some heating
and deterioration of the plug over time.
A 13A fuse passing 4A will give off 0.09W, resulting in less heating
in the plug and longer life.
Unless the heater has a longer flex than is allowed by EU regulations
(which requires the flex is protected against fault current when fused
at 16A), a 13A fuse will protect the cable OK.
(A BS1362 fuse gives off about 1W at full load current.)
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
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