I found a 7 amp fuse. Can I fit it to my coffee filter machine, which is rated at 1100 watts?
Am I correct in thinking that for applicances without a motor the calculation is (volts) x (amps) plus (small margin) but for appliances with a motor a much bigger fuse is usually needed because of surge current when the motor starts?
if it is a BS 1362 fuse so also the right size, rated for 240V, not prone to explode...
Yes and you'd need a pretty large and sustained surge, you might even be able to use a 5 amp fuse. But as you get closer to the fuses rating passing that current will (due to the fuses resistance) the fuse wire will get warm and so will the fuse, if on for long periods which a coffee maker is unlikely to get to that stage.
I also have a dozen or so 1, 2, 7 and 10 amp mains fuses. But here we seem to have a policy of either using 3A or 13A fuses.
For a purely resistive load like a heater, the power factor will be very close to 1 so, as you say, you can use power = voltage x current.
You need to take power factor into account when dealing with non-resistive loads like motors, but that's not an issue with a simple heating element.
Mostly yes, but are you sure it does not use any other electro mechanical device or something with big capacitors to charge via a power supply? I've also come across fast and slow blow fuses of the same rating, the fast blow ones have the wire under tension of a spring.
While on the subject of dissipation. I do notice quite a lot of fan heaters can actually warm their mains cable noticeable during use at 3KW. I've often wondered if this is entirely safe? Brian
I've yet to notice any explode, they may thud a bit. One of the most annoying things is that some fuses seem to lose connections due to the dry joint on the cap end after some years, so they don't blow just kind of act like a resistor. Brian
Most of the plugs still come with either no fuse at all or a 13a one. I've not actually checked devices with moulded on fuses of late, one just trusts the maker to know, but of course if the fuse fails but not due to an appliance fault many people bung in a 13a and never bother to look at the old one. Brian
About the worst in domestic use is the fridge/freezer. Often a couple of amps or less when running but will take out a 10A fuse on starting if it's a biggish motor. My knowledge is 30 years out of date, btw, so the starting might have changed nowadays. There's a device which utilises the surge at switch-on to pull in the start winding and then drops out as the motor starts and the current drops (klixon, IIRC). A 3-ph. 2.5kW motor has an enormous surge for about 1 - 3 cycles and it doesn't have a klixon. Single-phase motors do and the surge lasts a bit longer.
yes no problem, assuming it's a pukka mains plug fuse. 1100w = 4.5A
NT
"Brian Gaff \(Sofa 2\)" snipped-for-privacy@blueyonder.co.uk> wrote in news:qtiuf1$mo8$ snipped-for-privacy@news.albasani.net:
My Dyson Vacuum warms the cable!
I assume this is okay for appliances that are operated for a short period, always supervised, but perhaps less so for applicances left unattended.
To my surprise though, chargers can get quite warm; and they are left unattended for long periods.
Most flex is rated to 70C.
NT
Is it from a stairlift? They always have 7A fuses.
Dad's runs from a wall-wart ...
I've a little VAx cordless and the charging from 'flat' takes 6h (for "up to" - OK, it has a motorised brush that's witchable, so fair enough - 20m run-time). The charger is sort of luke-cool and goes to cold after charging is finished.
definitely don't mess with it then.
That would be the modern equivalent of a broomstick, I take it. Does it come with a black cat and pointy hat?
oops - bloody spell checker had his eyes shut.
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