On Thursday, 24 November 2016 23:28:26 UTC, John Rumm wrote:
On 24/11/2016 10:36, RayL12 wrote:
On 23/11/2016 1:23 PM, Roger Hayter wrote:
Dave Plowman (News) wrote:

In article ,
wrote:
So those chinese goods with barely 0.1mm2 are uprotected on a 13A fuse.

I ask again. Why are you buying such things that you know to be rubbish?
If you're not, no point in telling the world they should fit an
appropriate fuse, as they're not listening. And wouldn't understand
anyway.

And that 1960s hifi with 0.1mm dia mains wiring inside ditto.

Must have been real rubbish if it didn't have an equipment fuse.

Interestingly, I just had a counter-example where a 3A fuse might have
prevented equipment damage due to a fault. A Grundfos pump (mention
the name because it is the second one to do the same) failed
short-circuit and melted a trace on the controller PCB, without actually
blowing the 13A plug fuse or tripping the MCB. A 3A fuse might have
prevented this. However, I haven't checked whether the oil pump inrush
current is too high for a 3A fuse yet.



For me, this is where the fuse rating lies. Estimate the working current
of the device and limit the current input. Any mishaps handling the
circuitry will have the same current limit. Could be a life saver?


BS1362 fuses are quite sloppy in tolerance:

wiki.diyfaq.org.uk/index.php/File:BS1362FusingTime.png

So the 1 sec fusing time for a 3A fuse could represent anything from say
5A to 12A

Which is also why yuo shouldn;t use say a 3 amp fuse in a device that takes 3 amps for any lenght of time, because the fuse will run how and wonlt blow but could cause a fire which is why you'd use a 13 amp fuse now.
We still have 1 , 2, 3, 5, 7, 10 & 13amp fuses but the current :-) way of doing this is to have a 3 amp fuse or a 13 amp fuse in the plug.