Fuses

Maybe it depends on one's approach to vacuuming. If you stop and start frequently to move furniture etc, could the repeated surges overheat the fuse?

I would tend to be less concerned about appliances that are continuously supervised that about those left unattended.

Is the rating plate an average or maximum?

I don't think so. Off times give zero heat dissipation in the fuse.

Maximum excluding surges.

NT

Maximum operating - but that does not include inrush current.

I expect the after market for 13A fuses is tiny. Typically most things come with them fitted - so any active fuse changes will usually involve

(My stock of 13A fuses has grown with time, in spit of never having bought any).

Well yes, that covers most of the possibilities. Blows a fuse and catching fire also being possible.

I admire your faith. To work you would need sophisticated monitoring electronics integrated into every appliance, and they would need careful tuning by the manufacturer to recognise what is an unusual current profile for the appliance. Something that in many cases will not be possible, and prohibitively expensive in cases where it is. So in the real world economics will probably prevent that happening.

Solutions that work at the circuit level are typically very limited in effectiveness. (see the tests on circuit level AFCIs).

The "energy passed" or let-though only really takes on significance when interrupting fault currents. During normal operation, the energy delivery from any size of fuse will deliver to all intents and purposes unlimited power to start a fire.

I would contend that (particularly with modern appliances) plug fuses rarely have a significant influence in reducing appliance fires in non fault current scenarios.

If they did have significant influence, then you would expect the UK to show a notable reduction in electrical fires compared to the rest of Europe where plug fuses are not used, and the only protection outside of the appliance will be the 16 or 20A MCB for the circuit.

However we have more fires per person than say France, and a similar number compared to Germany.

(ans as you know, most electrical fires stem from misuse of appliances, followed some long way after by faulty appliances, with faulty fixed wiring some distance behind those)

The number of electrical fires seems to be dominated by the number of electrical appliances in use, so wealthy nations lead the way.

You are not recommending it, but you are going on about it - endlessly.

Especially when you are not really suggesting anything substantially different from what I said in my first post.

And while true in many cases, as a blanket statement its incorrect since there are counter examples.

In cases where its true, the amount of "safer" is very small and difficult to qualify for *most* cases.

So you agree with what I say, yet still feel the need to argue?

Its is rather missing the point. If you want to improve safety, don't use sub standard mains leads in the first place, don't try to cure their sins with a sprinkling of holy water after the fact.

You would be a negligent to use one in the first place. How can you seriously argue the merits of different fuse ratings when using a lead which poses orders of magnitude more risk?

Under normal operating conditions why would a fuse blow just because there is a break in the flex? It does not blow when you turn the appliance on and off with the switch, so why would it when you turn it on and off with a break in the flex?

Your logic is flawed[1], however I agree, no further debate is worthwhile.

Well the idea is to saturate the steel shadowmask and then let the magnetic field die away in order to de-mag the shadowmask.

As shown here around 3 mins in!

Its a wonder the whole thing worked considering the precision manufacture of the colour TV tube shown here...

Load characterisation & electronic protection has already been done. It's too expensive for home use. But computing power is very cheap, and getting cheaper. It won't take too long before it's built into whatever the future replacement for RCBOs is. There's no requirement to put them inside appliances.

of course. They do improve over time.

the reality is they frequently don't result in fire, things often burn to open circuit. So the let-through energy does matter.

History tells us otherwise. Imagine replacing them with bolts & tell us whether you're as safe.

which does a better job than a 13A fuse. Faster means less energy.

I'm going on about it no more than you. And it is not endless.

someone didn't pay attention

It is a challenge. I daresay looking into early electrical regs & insurance figures would answer that to some extent, but only as far as the the practices of the time, which were obviously a lot worse.

no

You can tell that to end users till you're blue in the face, it's not gonna happen because most don't know and some don't care.

I don't know anyone suggesting that

no, just a normal member of the public that knows no different.

that is precisely the sort of situation where good fusing practice makes most safety difference. The idea that all appliances out there in the UK are safe with a 13A fuse is simply well & truly wrong.

When flex etc shorts, either a fuse blows oc or the flex damage blows oc. Could be either.

If you think that you really haven't followed what's being said.

The safety benefit of appropriate fusing was established a very long time ago.

NT

That sounds like a very posh Michael Aspell

One tends to forget just how much on site tweaking was expected of an installer with some early colour sets.

Yup sure, I was not suggesting it would not work - you need a decaying magnetic field to do the degauss, and the thermistor will achieve that.

It was just the whole "leave it permanently live and in circuit" bit that seems a bit crude... Later sets and monitors often had a relay to switch it out when not being used.

Interesting how they etch the shadow mask, then use it to deposit the phosphors.

Good point. So has mine.

Doesn't everyone save the fuse from the moulded-on plug when disposing of yet another failed kettle/toaster/... ?

Most people seem to throw out everything they don't need in the next 5 minutes.

Once you have more than a lifetimes supply, not much point.

If it's any consolidation (to the cow) <1kV AC is *LOW* voltage