In article ,
wrote:
On Tuesday, 18 August 2020 10:55:44 UTC+1, Dave Plowman (News) wrote:
In article ,
Scott wrote:

Why do you think the system was introduced with 1, 2, 3, 5, 7, 10 and
13 amp fuses unless a lower rated fuse had safety benefits?

And it failed miserably.

On the contrary it was much more effective than the prior system

Really? With the previous radial system, you had a fuse per socket. In
theory...

So a 5 amp socket would take the fuse out if overloaded.


If a fuse blows, all the vast majority will do is
replace it to get it working again.

which is fine


And are very unlikely to have all
those values to hand. And the spares they are likely to find, 13 amp.

IME most people had 3A & 13A.

Your mileage appears to have varied, as they say.


Hence the current method of having wiring capable of taking out a 13
amp fuse if there is a sort somewhere without causing a fire. And
protecting the device itself with its own fuse if needed.

Yup. But historically it did work a lot better than the old 2/5/15A
system.


The old system was even more open to abuse - using the wrong fusewire, etc.

But the idea of using lots of different fuses for plug tops is downright
stupid too - unless it was impossible to fit the wrong one. Human nature
being as it is.

--
*INDECISION is the key to FLEXIBILITY *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Scott wrote:
On Tue, 18 Aug 2020 10:51:29 +0100, "Dave Plowman (News)"
wrote:

In article ,
Scott wrote:
Why do you think the system was introduced with 1, 2, 3, 5, 7, 10 and
13 amp fuses unless a lower rated fuse had safety benefits?

And it failed miserably. If a fuse blows, all the vast majority will do is
replace it to get it working again. And are very unlikely to have all
those values to hand. And the spares they are likely to find, 13 amp.

Hence the current method of having wiring capable of taking out a 13 amp
fuse if there is a sort somewhere without causing a fire. And protecting
the device itself with its own fuse if needed.

IMO changing to a 2 amp fuse can only nudge safety in one direction.

Most want something to work, before considering safety.

--
*I have never hated a man enough to give his diamonds back.

Dave Plowman London SW
To e-mail, change noise into sound.

On Tue, 18 Aug 2020 13:46:33 +0100, "Dave Plowman (News)"
wrote:
[snip]

The old system was even more open to abuse - using the wrong fusewire, etc.

Very true. We had a house with a fusebox with wired fuses. The
electrician coiled the fusewire round three times to make sure the
fuse did not blow.

On 18/08/2020 11:28, wrote:
On Tuesday, 18 August 2020 00:09:20 UTC+1, John Rumm wrote:
On 17/08/2020 22:09, tabbypurr wrote:
On Monday, 17 August 2020 21:57:17 UTC+1, John Rumm wrote:
On 17/08/2020 16:59, Scott wrote:

Why do you think the system was introduced with 1, 2, 3, 5, 7, 10
and 13 amp fuses unless a lower rated fuse had safety benefits?

For the limited cases where overload protection is useful. They
will all handle fault currents.

When the BS1362 plug system was introduced in '47 the plug fuse was
normally the appliance overload fuse, appliances mostly had little or
more often no other overload failure protection.

Agreed - hence why I mentioned it.

However a good deal of appliances (even then) don't actually need any
overload protection... So there is a danger that you could cause more
problems in the quest for "safety". (i.e. nuisance fuse blows, plugs
running warmer etc).

those aren't dangers.

A fuse blow might be a danger - depends on what its in, in what
circumstance, and who will try to fix it.

And putting a 3A fuse on a 2A load does not cause nuisance trips.

That depends on what that "2A" load is - what its surge characteristics
are, what inrush current it draws.

A CRT TV for example may only draw 150W when running normally, but may
take quite a bit more at switch on, and when degaussing.

More to the point, is the person choosing the fuse sufficiently aware of
the nature of the appliance to make a good assessment?

(I remember (a long while back) standing in the Waters & Stanton shop,
when someone walks in off the street, and asks if they have 2.5A 20mm
glass fuse. The young chap behind the counter says "yes, do you want
quick blow or anti surge?". The customer says, "oh, I don't know, its
for a portable TV, what do you think?". Sales droid thinks for a bit and
says "probably quick blow". I politely butt in, and ask the customer if
by any chance they have the original fuse with them? She does, so I get
her to read the rating off the fuse - and as you might expect it has a T
in it. So even the somewhat clued up person working in a shop stuffed
full of high tech electronics and comms gear can make the wrong call)

That has changed of
course, but there are still millions of appliances that have no
built-in overload protection and could benefit from it safety-wise.

I don't have a source of figures for how many are still out there. Do
you? Some, sure; millions perhaps?


ok I will bite...

I don't have a record of where they figures came from. But it's easy to come up with a very rough idea of the size of the issue.
1. How many substandard appliances have major retail sites sold?

What do you mean by substandard?

2. How many PAT fail appliances are there per site?

What site are we talking about? Home or work?

What proportion need & lack overload protection.

Few. (i.e. few will need it, and even fewer will lack it)

3. How many historic appliances are still in use? If you find just one per 63 people that's a million.

If you include all those babies using great grandpa's wireless huh?


Now before getting further into this, remember I have already said that
there are times when using a selected and appropriate fuse *is*
important, and we both understand that for the vast majority of
appliances people are using today, the fuse rating will have little if
any effect on safety so long as it provides adequate fault current
(official meaning!) protection.

I am not suggesting that fitting a more closely tolerances fuse is
necessarily wrong, only that it may introduce unintended circumstances,
and it many cases will achieve no improvement in safety.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Tue, 18 Aug 2020 13:47:41 +0100, "Dave Plowman (News)"
wrote:

In article ,
Scott wrote:
On Tue, 18 Aug 2020 10:51:29 +0100, "Dave Plowman (News)"
wrote:

In article ,
Scott wrote:
Why do you think the system was introduced with 1, 2, 3, 5, 7, 10 and
13 amp fuses unless a lower rated fuse had safety benefits?

And it failed miserably. If a fuse blows, all the vast majority will do is
replace it to get it working again. And are very unlikely to have all
those values to hand. And the spares they are likely to find, 13 amp.

Hence the current method of having wiring capable of taking out a 13 amp
fuse if there is a sort somewhere without causing a fire. And protecting
the device itself with its own fuse if needed.

IMO changing to a 2 amp fuse can only nudge safety in one direction.

Most want something to work, before considering safety.

True, but I have never encountered an appliance not working due to
being fitted with a 1 amp or 2 amp fuse.

On Tuesday, 18 August 2020 12:40:04 UTC+1, Andrew wrote:
On 18/08/2020 11:41, tabbypurr wrote:
On Tuesday, 18 August 2020 00:33:28 UTC+1, John Rumm wrote:
On 17/08/2020 22:09, Scott wrote:
On Mon, 17 Aug 2020 21:57:17 +0100, John Rumm
wrote:

On 17/08/2020 16:59, Scott wrote:
On Mon, 17 Aug 2020 16:20:35 +0100, John Rumm
wrote:

On 17/08/2020 14:04, Cursitor Doom wrote:
On Mon, 17 Aug 2020 02:12:17 +0100, John Rumm
wrote:

Why do you think the system was introduced with 1, 2, 3, 5, 7, 10 and
13 amp fuses unless a lower rated fuse had safety benefits?

For the limited cases where overload protection is useful. They will all
handle fault currents.

Whatever you call it, if there is only 2 amps of it instead of 13 amps
nothing will convince me that is not safer.

Define safer?

define waste of time

An elderly person getting ripped off after a blown fuse is 'diagnosed'
as a non-repairable item.

So if your life support system were to fail with a blown fuse when there
is a mains spike because some well meaning but uninformed person
replaced the manufacture fitted 13A fuse with a 2A one "because its
safer", that would be better?

With respect 99.999% of appliances are not life support. That different safety issues apply to that miniscule percentage is not news.



Most (many) domestic fires these days are caused by fake chargers and
/or rechargeable devices, including genuine ones that were not fakes.

Wibbling about fuses doesn't seem to be relevant to these.

What mode of action inside these appliances caused the fires? I'd wager it was in most cases insulation failure. Fuses do reduce fires resulting because they trip sooner in the process when less energy has been delivered to the flammable materials present.


You can include Soviet colour TV's in that group, but not our problem,

rarely, though I have had one.

though Hotpoint/Beko white goods are, even though they are fitted with
the 'correct' fuse.


NT

In article ,
Scott wrote:
Most want something to work, before considering safety.

True, but I have never encountered an appliance not working due to
being fitted with a 1 amp or 2 amp fuse.

Not even a fan heater? ;-)

I had an early colour TV. Said 500w on the back. But needed a 13 amp
fuse...

--
*Do infants enjoy infancy as much as adults enjoy adultery? *

Dave Plowman London SW
To e-mail, change noise into sound.

On Tuesday, 18 August 2020 13:48:11 UTC+1, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:
On Tuesday, 18 August 2020 10:55:44 UTC+1, Dave Plowman (News) wrote:
In article ,
Scott wrote:

Why do you think the system was introduced with 1, 2, 3, 5, 7, 10 and
13 amp fuses unless a lower rated fuse had safety benefits?

And it failed miserably.

On the contrary it was much more effective than the prior system

Really? With the previous radial system, you had a fuse per socket. In
theory...

not correct

So a 5 amp socket would take the fuse out if overloaded.

if the socket was overloaded by a large margin for long enough yes. But often not if the appliance went into dangerous overload. Why? Sockets were in short supply and most homeowners chose plugs to fit whatever socket was there rather than what fuse the appliance required. Those that stuck to fitting the corect plug simply used an unfused adaptor. Result: a large percentage of appliances were not appropriately fused.


If a fuse blows, all the vast majority will do is
replace it to get it working again.

which is fine


And are very unlikely to have all
those values to hand. And the spares they are likely to find, 13 amp.

IME most people had 3A & 13A.

Your mileage appears to have varied, as they say.

not really

Hence the current method of having wiring capable of taking out a 13
amp fuse if there is a sort somewhere without causing a fire. And
protecting the device itself with its own fuse if needed.

Yup. But historically it did work a lot better than the old 2/5/15A
system.


The old system was even more open to abuse - using the wrong fusewire, etc.

yup

But the idea of using lots of different fuses for plug tops is downright
stupid too - unless it was impossible to fit the wrong one. Human nature
being as it is.

Hardly. 3A fuses improve safety when used appropriately, there's no downside there.

'Impossible to fit the wrong one' would just recreate the inappropriate fusing issue that existed with the round pin system.


NT

On 18/08/2020 11:41, wrote:
On Tuesday, 18 August 2020 00:33:28 UTC+1, John Rumm wrote:
On 17/08/2020 22:09, Scott wrote:
On Mon, 17 Aug 2020 21:57:17 +0100, John Rumm
wrote:

On 17/08/2020 16:59, Scott wrote:
On Mon, 17 Aug 2020 16:20:35 +0100, John Rumm
wrote:

On 17/08/2020 14:04, Cursitor Doom wrote:
On Mon, 17 Aug 2020 02:12:17 +0100, John Rumm
wrote:

Why do you think the system was introduced with 1, 2, 3, 5,
7, 10 and 13 amp fuses unless a lower rated fuse had safety
benefits?

For the limited cases where overload protection is useful. They
will all handle fault currents.

Whatever you call it, if there is only 2 amps of it instead of 13
amps nothing will convince me that is not safer.

Define safer?


You're barking at nonexistent shadows there. Any appliance can get a
smouldering insulator fault that takes 3A but not 13A. That's one
way appliances catch fire.

And will that smouldering insulation result in an large enough rise in
current draw to blow a fuse?

(note the word "insulation" not well known for passing high currents)

Now there are some appliances that do have overload failure modes.
If

any insulator can fail smouldering. All appliances include
insulation.

See above.

The problem is, its easy to generate more than enough heat to start
combustion with only a kW of power to play with, and a fuse in a plug
will happily deliver that.

IMHO Smoke alarms, RCDs etc will make a far more meaningful contribution
to safety then obsessing about fuses in the vast majority of cases.

they are old enough, they may not include their own protection,
for

many modern ones don't either as your tablelamp example shows

Because it does not need it...

those, yes its important they are fitted with the "right" fuse.
For

ah, we agree after all

I said that right from the outset.

others it matters less than many worry about.

[1] 100A should be a fusing time well under 0.1 secs on a 13A fuse.
So for a PVC flex we can work out the conductor size required to
cope with the I^2 . t let through energy with the adiabatic
equation:

s = sqrt( 100 ^ 2 x 0.1 ) / 115 = 0.27mm minimum CSA

(115 being the k factor for PVC insulated cable)

So even the smallest typical 0.5mm^2 CSA flex would be fine with
any fuse.

Yup. But the chinese flea bay special with copper coated steel mains
lead would catch fire.

Since it probably has the dodgy non fused plug to go with it, its a moot
point!

(and many of those "fake" flexes would not take 3A sustained load anyway)

Proper flex that's partway broken also would
not cope, and that is not a rare failure mode.

Under fault conditions it may well blow at the weak part of the flex as
well. A fuse is not going to necessarily help even if it blows at the
same time. Under normal operating conditions the appliance may stop and
start or not work reliably - but again the fuse is not going to help.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Tuesday, 18 August 2020 15:15:34 UTC+1, John Rumm wrote:
On 18/08/2020 11:28, tabbypurr wrote:
On Tuesday, 18 August 2020 00:09:20 UTC+1, John Rumm wrote:
On 17/08/2020 22:09, tabbypurr wrote:
On Monday, 17 August 2020 21:57:17 UTC+1, John Rumm wrote:
On 17/08/2020 16:59, Scott wrote:

Why do you think the system was introduced with 1, 2, 3, 5, 7, 10
and 13 amp fuses unless a lower rated fuse had safety benefits?

For the limited cases where overload protection is useful. They
will all handle fault currents.

When the BS1362 plug system was introduced in '47 the plug fuse was
normally the appliance overload fuse, appliances mostly had little or
more often no other overload failure protection.

Agreed - hence why I mentioned it.

However a good deal of appliances (even then) don't actually need any
overload protection... So there is a danger that you could cause more
problems in the quest for "safety". (i.e. nuisance fuse blows, plugs
running warmer etc).

those aren't dangers.

A fuse blow might be a danger - depends on what its in, in what
circumstance, and who will try to fix it.

It isn't. If you want to propose compulsory self resetting MCBs or polyfuses etc you can, but that's a separate issue with its own tradeoffs each way.


And putting a 3A fuse on a 2A load does not cause nuisance trips.

That depends on what that "2A" load is - what its surge characteristics
are, what inrush current it draws.

A CRT TV for example may only draw 150W when running normally, but may
take quite a bit more at switch on, and when degaussing.

We know people can fit the wrong fuse. So what?


More to the point, is the person choosing the fuse sufficiently aware of
the nature of the appliance to make a good assessment?

Not inherently. Fuses used to come with lists of appliance types for each fuse value. Fitting a 13A in lieu of a 3 is not a problem, fitting a 3 when suitable is a small gain in fire satfey.


(I remember (a long while back) standing in the Waters & Stanton shop,
when someone walks in off the street, and asks if they have 2.5A 20mm
glass fuse. The young chap behind the counter says "yes, do you want
quick blow or anti surge?". The customer says, "oh, I don't know, its
for a portable TV, what do you think?". Sales droid thinks for a bit and
says "probably quick blow". I politely butt in, and ask the customer if
by any chance they have the original fuse with them? She does, so I get
her to read the rating off the fuse - and as you might expect it has a T
in it. So even the somewhat clued up person working in a shop stuffed
full of high tech electronics and comms gear can make the wrong call)

IME one is lucky if the person behind the counter is clued up. Glass fuses are a separate issue to what we're discussing of course.


That has changed of
course, but there are still millions of appliances that have no
built-in overload protection and could benefit from it safety-wise.

I don't have a source of figures for how many are still out there. Do
you? Some, sure; millions perhaps?


ok I will bite...

I don't have a record of where they figures came from. But it's easy to come up with a very rough idea of the size of the issue.
1. How many substandard appliances have major retail sites sold?

What do you mean by substandard?

not meeting the legal requirements


2. How many PAT fail appliances are there per site?

What site are we talking about? Home or work?

all of them!


What proportion need & lack overload protection.

Few. (i.e. few will need it, and even fewer will lack it)

Bzzt. Lots lack it.


3. How many historic appliances are still in use? If you find just one per 63 people that's a million.

If you include all those babies using great grandpa's wireless huh?

are there any of those? I doubt it. But there are plenty of old heaters still in use, old lamps with undersize flex etc etc.


Now before getting further into this, remember I have already said that
there are times when using a selected and appropriate fuse *is*
important, and we both understand that for the vast majority of
appliances people are using today, the fuse rating will have little if
any effect on safety so long as it provides adequate fault current
(official meaning!) protection.

no, a lower fuse equals less energy delivered to the smouldering insulator before trip. Result: lower fire risk.


I am not suggesting that fitting a more closely tolerances fuse is
necessarily wrong, only that it may introduce unintended circumstances,
and it many cases will achieve no improvement in safety.

It always reduces fire risk. And fire is the number 1 means by which electrical failure results in injury, loss of property and death.


NT

In article ,
wrote:
Really? With the previous radial system, you had a fuse per socket. In
theory...

not correct

Then correct me.

That's how my parents 1930s house was wired originally. Of course later on
sockets were added to a radial.

--
*Money isn‘t everything, but it sure keeps the kids in touch

Dave Plowman London SW
To e-mail, change noise into sound.

On Tuesday, 18 August 2020 15:37:12 UTC+1, John Rumm wrote:
On 18/08/2020 11:41, tabbypurr wrote:
On Tuesday, 18 August 2020 00:33:28 UTC+1, John Rumm wrote:
On 17/08/2020 22:09, Scott wrote:
On Mon, 17 Aug 2020 21:57:17 +0100, John Rumm
wrote:
On 17/08/2020 16:59, Scott wrote:
On Mon, 17 Aug 2020 16:20:35 +0100, John Rumm
wrote:
On 17/08/2020 14:04, Cursitor Doom wrote:
On Mon, 17 Aug 2020 02:12:17 +0100, John Rumm
wrote:

Why do you think the system was introduced with 1, 2, 3, 5,
7, 10 and 13 amp fuses unless a lower rated fuse had safety
benefits?

For the limited cases where overload protection is useful. They
will all handle fault currents.

Whatever you call it, if there is only 2 amps of it instead of 13
amps nothing will convince me that is not safer.

Define safer?


You're barking at nonexistent shadows there. Any appliance can get a
smouldering insulator fault that takes 3A but not 13A. That's one
way appliances catch fire.

And will that smouldering insulation result in an large enough rise in
current draw to blow a fuse?

Often yes, often not. Ultimately it either burns out without harm, blows a fuse or catches fire.

(note the word "insulation" not well known for passing high currents)

On the contrary, it's how electrical fires mostly start


Now there are some appliances that do have overload failure modes.
If

any insulator can fail smouldering. All appliances include
insulation.

See above.

The problem is, its easy to generate more than enough heat to start
combustion with only a kW of power to play with, and a fuse in a plug
will happily deliver that.

Indeed. That will be solved some time in the future by electronic load characterising fuse type circuits. For now we use fuses & mcbs which we know only catch a percentage of such events. A 3A fuse catches more than a 13A fuse, it blows with less energy passed.


IMHO Smoke alarms, RCDs etc will make a far more meaningful contribution
to safety then obsessing about fuses in the vast majority of cases.

Indeed. Correct fusing is still wise. I don't think anyone recommended obsession though. We just pointed out that picking an appropriate fuse is safer.. Trying to suggest that is obsession is childish.


they are old enough, they may not include their own protection,
for

many modern ones don't either as your tablelamp example shows

Because it does not need it...

Generally true. Of course there are also appliances that do.


those, yes its important they are fitted with the "right" fuse.
For

ah, we agree after all

I said that right from the outset.

others it matters less than many worry about.

[1] 100A should be a fusing time well under 0.1 secs on a 13A fuse.
So for a PVC flex we can work out the conductor size required to
cope with the I^2 . t let through energy with the adiabatic
equation:

s = sqrt( 100 ^ 2 x 0.1 ) / 115 = 0.27mm minimum CSA

(115 being the k factor for PVC insulated cable)

So even the smallest typical 0.5mm^2 CSA flex would be fine with
any fuse.

Yup. But the chinese flea bay special with copper coated steel mains
lead would catch fire.

Since it probably has the dodgy non fused plug to go with it, its a moot
point!

most don't have those. Picking a fuse to reduce fire risk is not a moot point, it is the central point of this thread & good sensible practice.


(and many of those "fake" flexes would not take 3A sustained load anyway)

many do, some don't


Proper flex that's partway broken also would
not cope, and that is not a rare failure mode.

Under fault conditions it may well blow at the weak part of the flex as
well. A fuse is not going to necessarily help even if it blows at the
same time. Under normal operating conditions the appliance may stop and
start or not work reliably - but again the fuse is not going to help.

The flex may blow oc, the fuse may blow preventing a fire or the flex may catch fire. A fuse that lets less energy through before blow improves the odds. I'm not sure there's much serious debate left on that point.


NT

On 18/08/2020 11:45, wrote:
On Tuesday, 18 August 2020 00:57:27 UTC+1, John Rumm wrote:
On 17/08/2020 23:04, tabbypurr wrote:
On Monday, 17 August 2020 22:29:49 UTC+1, Cursitor Doom wrote:

You frequently use the term "fault current" which crops up
frequently when professional electrical engineers are discussing
installations. However, for everyone else, it requires
clarification. I'm not an electrician, so I have no idea when you
use that term whether you're referring to *short circuit* current
or *earth leakage* current or something else altogether (unless you
use an example as you did above but even that's not watertight).
And then there's that lot that read this through Homeownershub -
God only knows what *they* make of it. ;-


The electrical wiring regs' meaning of 'fault' is a hard zero ohm L-N
short..

or L-E

John uses that meaning. Those of us that are more into
repairing things tend to use 'fault' to mean any failure to operate
correctly. The I with some Es seems to like to define existing terms
differently to everyone else, classic communication poor practice.

Being one who also repairs stuff, I am fully aware that the colloquial
use of "fault" is far less specific than that when used in engineering
and standards documentation for electrical systems.

No, the usage of 'fault' to mean zero ohm short only is specific to UK wiring regs not specific to engineering.

The UK wiring regs don't use "Fault" to mean zero ohm.

"Fault Current", is a specialist English and an engineering term used
by many, not only in the UK.

However if you are
going to have a meaningful discussion on fusing etc, it is quite
important that everyone uses a consistent set of terms when it matters.

Good luck with that

Make up your own terms if you like, if you think it will help.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 18/08/2020 15:14, Scott wrote:
On Tue, 18 Aug 2020 13:46:33 +0100, "Dave Plowman (News)"
wrote:
[snip]

The old system was even more open to abuse - using the wrong fusewire, etc.

Very true. We had a house with a fusebox with wired fuses. The
electrician coiled the fusewire round three times to make sure the
fuse did not blow.


Around what ?. There is a slot in the fuse holder that the wire
sits inside. Do you mean he coiled it round something like a pencil,
or looped it back and forward again ?. This just means there is
contact between the loops, surely ?.

On Tuesday, 18 August 2020 15:51:36 UTC+1, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:

Really? With the previous radial system, you had a fuse per socket. In
theory...

not correct

Then correct me.

That's how my parents 1930s house was wired originally. Of course later on
sockets were added to a radial.

Yes, it's what was done in the 1930s. Later it was typical to find a bunch of sockets on each fusebox fuse, and often the socket ratings did not match the fuse. So eg one might see 15A, 15A, 5A, 5A sockets on one 15A fuse.

Add the widespread use of unfused adaptors & end users' tendency to use whatever plug fitted the available socket & the 2/5/15A fusing system routinely descended into not being effective. This left the use of commonly 5 different mains plug types as often no more than madness.


NT

On 18/08/2020 15:32, wrote:
On Tuesday, 18 August 2020 13:48:11 UTC+1, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:
On Tuesday, 18 August 2020 10:55:44 UTC+1, Dave Plowman (News) wrote:
In article ,
Scott wrote:

Why do you think the system was introduced with 1, 2, 3, 5, 7, 10 and
13 amp fuses unless a lower rated fuse had safety benefits?

And it failed miserably.

On the contrary it was much more effective than the prior system

Really? With the previous radial system, you had a fuse per socket. In
theory...

not correct

So a 5 amp socket would take the fuse out if overloaded.

if the socket was overloaded by a large margin for long enough yes. But often not if the appliance went into dangerous overload. Why? Sockets were in short supply and most homeowners chose plugs to fit whatever socket was there rather than what fuse the appliance required. Those that stuck to fitting the corect plug simply used an unfused adaptor. Result: a large percentage of appliances were not appropriately fused.


Missing or inadequate earthing probably killed more people though.

On 18/08/2020 15:29, Dave Plowman (News) wrote:
In article ,
Scott wrote:
Most want something to work, before considering safety.

True, but I have never encountered an appliance not working due to
being fitted with a 1 amp or 2 amp fuse.

Not even a fan heater? ;-)

I had an early colour TV. Said 500w on the back. But needed a 13 amp
fuse...


deguassing ?

On Tuesday, 18 August 2020 15:58:52 UTC+1, John Rumm wrote:
On 18/08/2020 11:45, tabbypurr wrote:
On Tuesday, 18 August 2020 00:57:27 UTC+1, John Rumm wrote:
On 17/08/2020 23:04, tabbypurr wrote:
On Monday, 17 August 2020 22:29:49 UTC+1, Cursitor Doom wrote:

You frequently use the term "fault current" which crops up
frequently when professional electrical engineers are discussing
installations. However, for everyone else, it requires
clarification. I'm not an electrician, so I have no idea when you
use that term whether you're referring to *short circuit* current
or *earth leakage* current or something else altogether (unless you
use an example as you did above but even that's not watertight).
And then there's that lot that read this through Homeownershub -
God only knows what *they* make of it. ;-


The electrical wiring regs' meaning of 'fault' is a hard zero ohm L-N
short..

or L-E

John uses that meaning. Those of us that are more into
repairing things tend to use 'fault' to mean any failure to operate
correctly. The I with some Es seems to like to define existing terms
differently to everyone else, classic communication poor practice.

Being one who also repairs stuff, I am fully aware that the colloquial
use of "fault" is far less specific than that when used in engineering
and standards documentation for electrical systems.

No, the usage of 'fault' to mean zero ohm short only is specific to UK wiring regs not specific to engineering.

The UK wiring regs don't use "Fault" to mean zero ohm.

"Fault Current", is a specialist English and an engineering term used
by many, not only in the UK.

AIUI fault current does mean the current resulting from a zero ohm connection from live to not live.


However if you are
going to have a meaningful discussion on fusing etc, it is quite
important that everyone uses a consistent set of terms when it matters.

Good luck with that

Make up your own terms if you like, if you think it will help.

No need. 'Fault' is in widespread use to mean any failure, including in engineering.


NT

On Tuesday, 18 August 2020 16:01:07 UTC+1, Andrew wrote:
On 18/08/2020 15:32, tabbypurr wrote:
On Tuesday, 18 August 2020 13:48:11 UTC+1, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:
On Tuesday, 18 August 2020 10:55:44 UTC+1, Dave Plowman (News) wrote:
In article ,
Scott wrote:

Why do you think the system was introduced with 1, 2, 3, 5, 7, 10 and
13 amp fuses unless a lower rated fuse had safety benefits?

And it failed miserably.

On the contrary it was much more effective than the prior system

Really? With the previous radial system, you had a fuse per socket. In
theory...

not correct

So a 5 amp socket would take the fuse out if overloaded.

if the socket was overloaded by a large margin for long enough yes. But often not if the appliance went into dangerous overload. Why? Sockets were in short supply and most homeowners chose plugs to fit whatever socket was there rather than what fuse the appliance required. Those that stuck to fitting the corect plug simply used an unfused adaptor. Result: a large percentage of appliances were not appropriately fused.


Missing or inadequate earthing probably killed more people though.

AFAIK fire has always been the main electrical killer.


NT

On 18/08/2020 16:07, John Rumm wrote:
On 18/08/2020 13:46, Dave Plowman (News) wrote:

But the idea of using lots of different fuses for plug tops is downright
stupid too - unless it was impossible to fit the wrong one. Human nature
being as it is.

That fact that stuff comes with a pre-fitted plug these days, has lead
to a generation that now no longer know how to fit one, and in many
cases probably probably don't even know what a fuse looks like.



I am old enough to remember wire colours before blue for neutral, brown
for live and green/yellow for earth became commonplace...

it was red for live, black for neutral and green for earth.....

:-)

In article ,
Dave Plowman (News) wrote:
In article ,
Scott wrote:
Most want something to work, before considering safety.

True, but I have never encountered an appliance not working due to
being fitted with a 1 amp or 2 amp fuse.

Not even a fan heater? ;-)

I had an early colour TV. Said 500w on the back. But needed a 13 amp
fuse...

The degaussing coils created quite a surge at switch on,

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

In article , Andrew
wrote:
On 18/08/2020 15:14, Scott wrote:
On Tue, 18 Aug 2020 13:46:33 +0100, "Dave Plowman (News)"
wrote: [snip]

The old system was even more open to abuse - using the wrong fusewire,
etc.

Very true. We had a house with a fusebox with wired fuses. The
electrician coiled the fusewire round three times to make sure the fuse
did not blow.


Around what ?. There is a slot in the fuse holder that the wire sits
inside. Do you mean he coiled it round something like a pencil, or looped
it back and forward again ?. This just means there is contact between the
loops, surely ?.

some fuses were screw-in and therefore round.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On 18/08/2020 16:30, No Name wrote:
On 18/08/2020 16:07, John Rumm wrote:
On 18/08/2020 13:46, Dave Plowman (News) wrote:

But the idea of using lots of different fuses for plug tops is downright
stupid too - unless it was impossible to fit the wrong one. Human nature
being as it is.

That fact that stuff comes with a pre-fitted plug these days, has lead
to a generation that now no longer know how to fit one, and in many
cases probably probably don't even know what a fuse looks like.



I am old enough to remember wire colours before blue for neutral, brown
for live and green/yellow for earth became commonplace...

it was red for live, black for neutral and green for earth.....

:-)

Or a mushy grey for quite a few people :-(

In article ,
No Name wrote:
On 18/08/2020 16:07, John Rumm wrote:
On 18/08/2020 13:46, Dave Plowman (News) wrote:

But the idea of using lots of different fuses for plug tops is
downright stupid too - unless it was impossible to fit the wrong one.
Human nature being as it is.

That fact that stuff comes with a pre-fitted plug these days, has lead
to a generation that now no longer know how to fit one, and in many
cases probably probably don't even know what a fuse looks like.



I am old enough to remember wire colours before blue for neutral, brown
for live and green/yellow for earth became commonplace...

it was red for live, black for neutral and green for earth.....

and the fun came if you had a German made appliance. Red for earth ......

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On 18/08/2020 15:44, wrote:
On Tuesday, 18 August 2020 15:15:34 UTC+1, John Rumm wrote:
On 18/08/2020 11:28, tabbypurr wrote:
On Tuesday, 18 August 2020 00:09:20 UTC+1, John Rumm wrote:
On 17/08/2020 22:09, tabbypurr wrote:
On Monday, 17 August 2020 21:57:17 UTC+1, John Rumm wrote:
On 17/08/2020 16:59, Scott wrote:

Why do you think the system was introduced with 1, 2, 3, 5, 7, 10
and 13 amp fuses unless a lower rated fuse had safety benefits?

For the limited cases where overload protection is useful. They
will all handle fault currents.

When the BS1362 plug system was introduced in '47 the plug fuse was
normally the appliance overload fuse, appliances mostly had little or
more often no other overload failure protection.

Agreed - hence why I mentioned it.

However a good deal of appliances (even then) don't actually need any
overload protection... So there is a danger that you could cause more
problems in the quest for "safety". (i.e. nuisance fuse blows, plugs
running warmer etc).

those aren't dangers.

A fuse blow might be a danger - depends on what its in, in what
circumstance, and who will try to fix it.

It isn't.

Its not panto season yet.






--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 18/08/2020 16:03, wrote:
On Tuesday, 18 August 2020 15:58:52 UTC+1, John Rumm wrote:
On 18/08/2020 11:45, tabbypurr wrote:
On Tuesday, 18 August 2020 00:57:27 UTC+1, John Rumm wrote:
On 17/08/2020 23:04, tabbypurr wrote:
On Monday, 17 August 2020 22:29:49 UTC+1, Cursitor Doom wrote:

You frequently use the term "fault current" which crops up
frequently when professional electrical engineers are discussing
installations. However, for everyone else, it requires
clarification. I'm not an electrician, so I have no idea when you
use that term whether you're referring to *short circuit* current
or *earth leakage* current or something else altogether (unless you
use an example as you did above but even that's not watertight).
And then there's that lot that read this through Homeownershub -
God only knows what *they* make of it. ;-


The electrical wiring regs' meaning of 'fault' is a hard zero ohm L-N
short..

or L-E

John uses that meaning. Those of us that are more into
repairing things tend to use 'fault' to mean any failure to operate
correctly. The I with some Es seems to like to define existing terms
differently to everyone else, classic communication poor practice.

Being one who also repairs stuff, I am fully aware that the colloquial
use of "fault" is far less specific than that when used in engineering
and standards documentation for electrical systems.

No, the usage of 'fault' to mean zero ohm short only is specific to UK wiring regs not specific to engineering.

The UK wiring regs don't use "Fault" to mean zero ohm.

"Fault Current", is a specialist English and an engineering term used
by many, not only in the UK.

AIUI fault current does mean the current resulting from a zero ohm connection from live to not live.

No, you can have line to line fault currents (and line to neutral is
also "live to live" if one is being a pedant)

However if you are
going to have a meaningful discussion on fusing etc, it is quite
important that everyone uses a consistent set of terms when it matters.

Good luck with that

Make up your own terms if you like, if you think it will help.

No need. 'Fault' is in widespread use to mean any failure, including in engineering.

and "Fault Current" is not, So why use Fault if you mean Fault Current?


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Tue, 18 Aug 2020 15:59:13 +0100, Andrew
wrote:

On 18/08/2020 15:14, Scott wrote:
On Tue, 18 Aug 2020 13:46:33 +0100, "Dave Plowman (News)"
wrote:
[snip]

The old system was even more open to abuse - using the wrong fusewire, etc.

Very true. We had a house with a fusebox with wired fuses. The
electrician coiled the fusewire round three times to make sure the
fuse did not blow.


Around what ?. There is a slot in the fuse holder that the wire
sits inside. Do you mean he coiled it round something like a pencil,
or looped it back and forward again ?. This just means there is
contact between the loops, surely ?.

There were screws top and the bottom. The idea was to loop the
fusewire round one screw and tighten it, then to do the same with the
other screw. Before you say it, yes sometimes the fusewire would
break when you tightened the second screw so it was best to leave a
suitable amount of slack to allow for this.

On Tue, 18 Aug 2020 16:30:33 +0100, No Name
wrote:

On 18/08/2020 16:07, John Rumm wrote:
On 18/08/2020 13:46, Dave Plowman (News) wrote:

But the idea of using lots of different fuses for plug tops is downright
stupid too - unless it was impossible to fit the wrong one. Human nature
being as it is.

That fact that stuff comes with a pre-fitted plug these days, has lead
to a generation that now no longer know how to fit one, and in many
cases probably probably don't even know what a fuse looks like.



I am old enough to remember wire colours before blue for neutral, brown
for live and green/yellow for earth became commonplace...

it was red for live, black for neutral and green for earth.....

Not that long ago. The cables in my flat (not flexes) are mostly in
these colours with a warning sticker at the consumer unit saying two
colour systems are in use.

On Tue, 18 Aug 2020 15:29:33 +0100, "Dave Plowman (News)"
wrote:

In article ,
Scott wrote:
Most want something to work, before considering safety.

True, but I have never encountered an appliance not working due to
being fitted with a 1 amp or 2 amp fuse.

Not even a fan heater? ;-)

No - fan heaters are fitted with 13 amp fuses. Generally each element
is 1 Kilowatt.

I had an early colour TV. Said 500w on the back. But needed a 13 amp
fuse...

That's because of the surge when you switch on. Same applies to
anything with a motor, such as a vacuum cleaner. You can't just go by
the rating plate.

On 18/08/2020 18:33, Scott wrote:
On Tue, 18 Aug 2020 16:30:33 +0100, No Name
wrote:

On 18/08/2020 16:07, John Rumm wrote:
On 18/08/2020 13:46, Dave Plowman (News) wrote:

But the idea of using lots of different fuses for plug tops is downright
stupid too - unless it was impossible to fit the wrong one. Human nature
being as it is.

That fact that stuff comes with a pre-fitted plug these days, has lead
to a generation that now no longer know how to fit one, and in many
cases probably probably don't even know what a fuse looks like.



I am old enough to remember wire colours before blue for neutral, brown
for live and green/yellow for earth became commonplace...

it was red for live, black for neutral and green for earth.....

Not that long ago. The cables in my flat (not flexes) are mostly in
these colours with a warning sticker at the consumer unit saying two
colour systems are in use.



For fixed wiring in a domestic house the colours of red, green and black
last for far longer than for cables for appliances....... think the
former must have been early 2000s and the latter late 70's/early 80's?

In article ,
No Name wrote:
On 18/08/2020 18:33, Scott wrote:
On Tue, 18 Aug 2020 16:30:33 +0100, No Name
wrote:

On 18/08/2020 16:07, John Rumm wrote:
On 18/08/2020 13:46, Dave Plowman (News) wrote:

But the idea of using lots of different fuses for plug tops is downright
stupid too - unless it was impossible to fit the wrong one. Human nature
being as it is.

That fact that stuff comes with a pre-fitted plug these days, has lead
to a generation that now no longer know how to fit one, and in many
cases probably probably don't even know what a fuse looks like.



I am old enough to remember wire colours before blue for neutral, brown
for live and green/yellow for earth became commonplace...

it was red for live, black for neutral and green for earth.....

Not that long ago. The cables in my flat (not flexes) are mostly in
these colours with a warning sticker at the consumer unit saying two
colour systems are in use.



For fixed wiring in a domestic house the colours of red, green and black
last for far longer than for cables for appliances....... think the
former must have been early 2000s and the latter late 70's/early 80's?

fixed wiring colours changed with the 17th Edition of the Wiring Regs 2008.
Flexes in the 15th Edition - 1981

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On 17/08/2020 22:29, Cursitor Doom wrote:
On Mon, 17 Aug 2020 21:57:17 +0100, John Rumm
wrote:

On 17/08/2020 16:59, Scott wrote:
On Mon, 17 Aug 2020 16:20:35 +0100, John Rumm
wrote:

On 17/08/2020 14:04, Cursitor Doom wrote:
On Mon, 17 Aug 2020 02:12:17 +0100, John Rumm
wrote:


If it were a BS1362 style fuse, the looking a bit to the left of the 3A
fuse curve would suggest that it might take 3A indefinitely:

http://wiki.diyfaq.org.uk/images/d/d...FusingTime.png


Yeah, here's a picture of the exact type he


https://images-na.ssl-images-amazon...._AC_SX355_.jpg

Probably fake - the end caps look too shiny to be Bussman

Here are some tell tails:

https://www.pat-testing-training.net...fake-fuses.php

(there is also more to a fuse than will it blow at an appropriate level
of overload. Actually having the capacity to interrupt the flow of
current, and not exploding in your face being some important ones!)

Seems there's even more leaway than I'd expected for extended
over-current tolerance. Perhaps we should never fit anything bigger
than a 10A fuse in a 13A plug? I think I'll toss out all my 13A fuses
to be on the safe side.

You could flip the argument, and say never fit anything other than a 13A
fuse. The purpose of the fuse (for any moderately recent appliance
anyway) is to provide *fault* protection to the flex - and a 13A fuse
will do that just fine.

The exceptions to this are some low quality multiway extension leads
where 10A would be more appropriate, or for historic appliances and
flexs, or cases where a manufacturer explicitly cites a smaller fuse.

I have seen this argument so many times before and have never
understood it at all.

ok.

I acquired a supply of 2 amp fuses and fitted
them to various low current appliances, without any difficulties. How
anyone can argue that limiting the fault current is anything other
than a safety enhancement confounds me.

Because you are confusing fault current with overload current. Fuses (or
any other circuit protection device have *no* ability to limit fault
currents. The only thing that limits a fault current the round trip
impedance of the circuit with the fault. So if that is 0.23 ohms, then
your fault current is 1,000 A regardless of the fuse fitted.

That will open any BS 1362 fuse pretty sharpish - the nominal current
rating is not important.

What matters is that the fuse has the breaking capacity to clear the
fault before something else (like the appliance flex) is destroyed /
catches fire.

This is a *totally different* discussion from overload protection - foe
example fitting a 13A fuse to a spur feeding multiple sockets on a ring
circuit.

Why do you think the system was introduced with 1, 2, 3, 5, 7, 10 and
13 amp fuses unless a lower rated fuse had safety benefits?

For the limited cases where overload protection is useful. They will all
handle fault currents.


You frequently use the term "fault current" which crops up frequently
when professional electrical engineers are discussing installations.
However, for everyone else, it requires clarification. I'm not an
electrician, so I have no idea when you use that term whether you're
referring to *short circuit* current or *earth leakage* current or
something else altogether (unless you use an example as you did above
but even that's not watertight). And then there's that lot that read
this through Homeownershub - God only knows what *they* make of it.
;-




The regs only apply two cases.

A LN or LE short which is a "fault current". This means there is a fault.

Or an overload current. This means an MCB or fuse has been run at more
than it's rated value for an extended period of time before
tripping/blowing. This is not classed as a fault as the circuit is
acting as required.

You would never expect an overload on a lighting circuit but when the CH
packs in at an office and everyone fetches a fan heater in and trips the
ring circuit then that circuit is behaving as it was designed to do.



--
Adam

On 18/08/2020 11:51, Scott wrote:
On Tue, 18 Aug 2020 10:51:29 +0100, "Dave Plowman (News)"
wrote:

In article ,
Scott wrote:
Why do you think the system was introduced with 1, 2, 3, 5, 7, 10 and
13 amp fuses unless a lower rated fuse had safety benefits?

And it failed miserably. If a fuse blows, all the vast majority will do is
replace it to get it working again. And are very unlikely to have all
those values to hand. And the spares they are likely to find, 13 amp.

Hence the current method of having wiring capable of taking out a 13 amp
fuse if there is a sort somewhere without causing a fire. And protecting
the device itself with its own fuse if needed.

IMO changing to a 2 amp fuse can only nudge safety in one direction.



Only if it is the real thing. And even them there is very little difference.


--
Adam

On 17/08/2020 22:47, Cursitor Doom wrote:
[...]
(with time it became clear that joe public was not equipped to make
sensible choices in this area, and the modern practice of ensuring that
if overload protection was required, then it must be in the appliance
itself and not on the end of the flex where it can be changed at the
whim of anyone with access to a fuse (or bit of tin foil).

We used to use strips of milk bottle tops back in the day. But I'm
giving my age away now. ;-)


And the age of your mother's milkman:-)

--
Adam

On Tue, 18 Aug 2020 20:30:33 +0100, ARW
wrote:

On 18/08/2020 11:51, Scott wrote:
On Tue, 18 Aug 2020 10:51:29 +0100, "Dave Plowman (News)"
wrote:

In article ,
Scott wrote:
Why do you think the system was introduced with 1, 2, 3, 5, 7, 10 and
13 amp fuses unless a lower rated fuse had safety benefits?

And it failed miserably. If a fuse blows, all the vast majority will do is
replace it to get it working again. And are very unlikely to have all
those values to hand. And the spares they are likely to find, 13 amp.

Hence the current method of having wiring capable of taking out a 13 amp
fuse if there is a sort somewhere without causing a fire. And protecting
the device itself with its own fuse if needed.

IMO changing to a 2 amp fuse can only nudge safety in one direction.

Only if it is the real thing. And even them there is very little difference.

Is the counterfeit risk inversely related to amperage then?

On 18/08/2020 18:33, Scott wrote:
On Tue, 18 Aug 2020 16:30:33 +0100, No Name
wrote:

On 18/08/2020 16:07, John Rumm wrote:
On 18/08/2020 13:46, Dave Plowman (News) wrote:

But the idea of using lots of different fuses for plug tops is downright
stupid too - unless it was impossible to fit the wrong one. Human nature
being as it is.

That fact that stuff comes with a pre-fitted plug these days, has lead
to a generation that now no longer know how to fit one, and in many
cases probably probably don't even know what a fuse looks like.



I am old enough to remember wire colours before blue for neutral, brown
for live and green/yellow for earth became commonplace...

it was red for live, black for neutral and green for earth.....

Not that long ago. The cables in my flat (not flexes) are mostly in
these colours with a warning sticker at the consumer unit saying two
colour systems are in use.

I suspect he is talking about when the colours used in *flexes* were
red, black, and solid green.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Tue, 18 Aug 2020 08:03:44 -0700 (PDT), wrote:

On Tuesday, 18 August 2020 15:58:52 UTC+1, John Rumm wrote:
On 18/08/2020 11:45, tabbypurr wrote:
On Tuesday, 18 August 2020 00:57:27 UTC+1, John Rumm wrote:
On 17/08/2020 23:04, tabbypurr wrote:
On Monday, 17 August 2020 22:29:49 UTC+1, Cursitor Doom wrote:

You frequently use the term "fault current" which crops up
frequently when professional electrical engineers are discussing
installations. However, for everyone else, it requires
clarification. I'm not an electrician, so I have no idea when you
use that term whether you're referring to *short circuit* current
or *earth leakage* current or something else altogether (unless you
use an example as you did above but even that's not watertight).
And then there's that lot that read this through Homeownershub -
God only knows what *they* make of it. ;-


The electrical wiring regs' meaning of 'fault' is a hard zero ohm L-N
short..

or L-E

John uses that meaning. Those of us that are more into
repairing things tend to use 'fault' to mean any failure to operate
correctly. The I with some Es seems to like to define existing terms
differently to everyone else, classic communication poor practice.

Being one who also repairs stuff, I am fully aware that the colloquial
use of "fault" is far less specific than that when used in engineering
and standards documentation for electrical systems.

No, the usage of 'fault' to mean zero ohm short only is specific to UK wiring regs not specific to engineering.

The UK wiring regs don't use "Fault" to mean zero ohm.

"Fault Current", is a specialist English and an engineering term used
by many, not only in the UK.

AIUI fault current does mean the current resulting from a zero ohm connection from live to not live.


However if you are
going to have a meaningful discussion on fusing etc, it is quite
important that everyone uses a consistent set of terms when it matters.

Good luck with that

Make up your own terms if you like, if you think it will help.

No need. 'Fault' is in widespread use to mean any failure, including in engineering.

Pretty much. I finally dug out my fairly new copy of the Oxford
Dictionary of Electronics and Electrical Engineering, which defines
fault current as: "A current that may flow through a circuit or device
as a result of a fault, such as a defect in the insulation. The
current may take the form of a short circuit, electrical surge,
current to earth etc."

I could be pedantic and take issue with the exact wording and the use
of the catch-all "etc"., but who am I (a mere 40th generation Angle)
to question such a source?

On Tue, 18 Aug 2020 16:07:33 +0100, John Rumm
wrote:

On 18/08/2020 13:46, Dave Plowman (News) wrote:

But the idea of using lots of different fuses for plug tops is downright
stupid too - unless it was impossible to fit the wrong one. Human nature
being as it is.

That fact that stuff comes with a pre-fitted plug these days, has lead
to a generation that now no longer know how to fit one, and in many
cases probably probably don't even know what a fuse looks like.

And looking increasingly like they'll forever be renters, will never
know what the inside of a DIY store looks like either. Have you
noticed all the punters in those places are the wrong side of 50
nowadays?

On Tue, 18 Aug 2020 15:16:37 +0100, Scott
wrote:

On Tue, 18 Aug 2020 13:47:41 +0100, "Dave Plowman (News)"
wrote:

In article ,
Scott wrote:
On Tue, 18 Aug 2020 10:51:29 +0100, "Dave Plowman (News)"
wrote:

In article ,
Scott wrote:
Why do you think the system was introduced with 1, 2, 3, 5, 7, 10 and
13 amp fuses unless a lower rated fuse had safety benefits?

And it failed miserably. If a fuse blows, all the vast majority will do is
replace it to get it working again. And are very unlikely to have all
those values to hand. And the spares they are likely to find, 13 amp.

Hence the current method of having wiring capable of taking out a 13 amp
fuse if there is a sort somewhere without causing a fire. And protecting
the device itself with its own fuse if needed.

IMO changing to a 2 amp fuse can only nudge safety in one direction.

Most want something to work, before considering safety.

True, but I have never encountered an appliance not working due to
being fitted with a 1 amp or 2 amp fuse.

Perhaps some new guidelines: fit a 10A fuse only for heating
appliances; 2A for everything else.

On Tue, 18 Aug 2020 16:42:03 +0100, charles
wrote:

In article ,
Dave Plowman (News) wrote:
In article ,
Scott wrote:
Most want something to work, before considering safety.

True, but I have never encountered an appliance not working due to
being fitted with a 1 amp or 2 amp fuse.

Not even a fan heater? ;-)

I had an early colour TV. Said 500w on the back. But needed a 13 amp
fuse...

The degaussing coils created quite a surge at switch on,

That's the kind of thing that T rated fuses are for. Fitting a regular
13A in those circumstances is just plain dumb.