Unless there is a surge on start up which can happen on heaters.
I'm very surprised we do not get 7.5 amp fuses for this sort of thing. 13
amp ones go with a heck of a bang. You can get very slow blow fuses of
course with a lot of that heat conducting stuff in them, but I'd guess a
lot of fuses one sees in pound shops are dodgy in the extreme.
This newsgroup posting comes to you directly from...
AIUI the type of heater that is in an incandescent lamp - filament, of
course - has low initial resistance so that it comes on 'instantaneously'
whereas an electric fire/kettle/shower is pretty well constant.
Cold inrush to a 3kW kettle+bad idea.
The 2 elements in my electric shower, measured when cold of course, have the
resistance corellating to the rated power.
The electric kettle stays the same, although the meter won't show the power
for the first cycle or two.
On Friday, 23 March 2018 01:50:20 UTC, email@example.com wrote:
But according to regulations in the UK on changing fuses it should be either a 3A for below 720W or a 13amp for above 720W .
On Friday, 23 March 2018 13:37:35 UTC, Andy Burns wrote:
As I said it's a bad question and in this university we have the regulations which tell us we must only use 3 & 13amp fuses, about 10 years ago I and others had the job of checking all fuses and replacving them with the 'correct ones'
i.e 3 or 5, this is one reason why I have dozens of 5, 7 and 10 amp fuses, I even have 1 amp and 2 amp that I used in angle poised lamps with 40 or 60w bulbs.
ANd don;t forget the FUSE is to protect the cable NOT the item of equipent so it really doesnlt matter what current rating the electric fire is, you put the fuse in that is correct for the cable.
Your view is too simplistic. Any fuse value below the rating of the
cable will protect it. Therefore a "univeral" cable rated at say 5amps
feeding an appliance rated at say 2 amps will still be protected by
using a fuse suitable for the appliance.
So a 13A fuse is perfect protection if the cable is thick enough and a
3A if it isn't. Its illegal to supply anything unsafe for use with a 3A
fuse. It may even be illegal to supply leads that are unsafe with a 13A
fuse if the regulations have been passed.
The idea that the plug fuse is solely to protect the flex is a pov much pro
moted, but a proper look at it shows it doesn't really add up.
Of course you can take that approach, but fitting better chosen fuses does
improve safety and costs zero extra, so is the more sensible thing to do. A
s the owner of many historic electrical goods & the occasional 3rd world im
port I'd hate to run any of them on a 13A fuse.
As ever such ideas lead to idiocy like people being ordered to replace appr
opriate fuses with higher rated ones etc.
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