Fusing down fans to 3 amp

[vxwestie]

So, following on from the "Prosecution" thread, who's now going to fuse down bathroom fans to 3amp?

Yes,

No,

 

[Fin170]

So a bathroom fan is on average about 10-25w, for it to actually draw well over 3 amps something pretty spectacular will have had to go wrong, more along the lines of direct short than fan stuck on. In which event the 6 amp MCB will beat the fuse


Or maybe I'm looking at it the wrong way and the manufacture is assuming the circuit is protected by 5 amp fuse wire, in which case it's anybodys guess between the fuse wire, 3 amp or fire brigade

All crap anyway, fan manufacture should of made their cables safe for over .1A, same for those 9.5kw showers that are full of 4mm

In conclusion, 3 amp MCBs :lol:

 

[MarkieSparkie]

...I still maintain that in nearly every instance a 6mcb would blow first in the event of a fault....

Sorry mate but you are wrong in that assumption:
Comparing data for a 6A BS 60898 Type B MCBs or BS 61009 RCBOs from BS7671:2008+A1:2011 Fig 3A4 and a 3A BS1362 Fuse from the Bussman catalogue datasheet:
6A MCB requires a prospective overload current of 30A to trip in the conventional time.
3A Fuse requires a prospective overload current of between 12 and 18A in the conventional time.
[FONT=&amp]Therefore discrimination is likely to be achieved

Also, [/FONT]BS 1362 specifies breaking-time/current characteristics for fuses with a current rating of 3A, the required breaking-time ranges quoted are: 0.2–80s at 9 A, < 0.1s at 20 A and < 0.03s at 30 A.
BS 1362 fuse short circuit capacity is 6kA.