On Friday, 10 January 2020 11:47:14 UTC, whisky-dave wrote:
On Thursday, 9 January 2020 18:10:09 UTC, tabby wrote:
On Thursday, 9 January 2020 13:14:57 UTC, whisky-dave wrote:
On Wednesday, 8 January 2020 23:10:33 UTC, tabby wrote:
On Wednesday, 8 January 2020 15:38:51 UTC, whisky-dave wrote:
On Wednesday, 8 January 2020 14:10:30 UTC, Terry Casey wrote:
In article 0b7058f1-2bb9-401d-999e-ac584814c973
@googlegroups.com, says...

On Tuesday, 7 January 2020 16:13:12 UTC, Terry Casey wrote:

The traditional method is silver paper from a cigarette packet
wrapped round the dead fuse. Perfect fit and lasts forever!

Does that silver paper conduct enough ?

It certainly did in the 60s!

I just measure some from a packet of silk cut.

0.019 ohms between two points 1 inch apart about the lenght of a mains fuse.

I didn't think this sort of silver paper conducted so much,
I'll never have to buy a fuse again.

All measured at about 1 inch spacing
Silver paper from a viscount chocolate bisciut 0.012 R
Aluminium foil at 0.009 R
a 13 amp fuse. at 0.002 R.

(Test Leads shorted together 0.0126 R )

measured using a LCR meter Agilent U1731C

Did you put prongs onto the foil or wrap it round an open fuse in a mains plug then measure? The latter would give lower R

My first test I used our standard meter probes that were suppl.ied woith our default~£30 meters,


when I realised the resistance was 1R I went and got the
Agilent U1731C meter and used the supplied lead with small croc clips
which looks like this

https://uk.rs-online.com/web/p/lcr-m...ories/7118054/
I put the croc clips to the flat foil(s)

When measuring the fuse I clipped the croc clips around the end of the fuse caps.



NT

If you ever get round to wrapping a dead fuse with the foil paper & fitting it into a plug you'll get lower R readings.

Of course but that low reading is only true if/when testing at low voltage and current.

it won't be much different when warm, but it will be much different when wrapped round a dead fuse.

The foil is only on one side too. I do not think that this foil paper could pass 13 amps.

I'm sure it could, but not sure for how long.


NT

On 01/01/2020 14:08, Scott wrote:
On Wed, 1 Jan 2020 05:21:54 -0800 (PST),
wrote:

On Monday, 30 December 2019 22:12:42 UTC, wrote:
Leads were often very thin, basically what we now call speaker wire.
Using under 3A fuses is wise if such wire is used.

Leads were also longer as people had fewer sockets. Remember the days you'd get a good 2 or 3 yards of flex on a table lamp.

Now all EU appliances are supposed to be okay with unfused plugs as that's normal in Europe, and leads are shorter to provide less resistance so a higher rated fuse/MCB blows quickly enough.

Lucky Golden Hedgehog leads from China are still on the thin side though.

If the purpose of the fuse is to protect the flex (as is often said),
does this mean all flexes can cope with 16 amps (European radial
circuit)?

Yup, that's the general idea... In most countries the option to protect
the flex at less than 16A is not usually available, so specifying the
maximum earth loop impedance of the lead is all you can do. Hence why
1.8m of 0.5mm^2 flex is common.

(whether actually true for some of the more dubious ebay tat etc is
another mater)


--
Cheers,

John.

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On 01/01/2020 13:07, Scott wrote:
On Wed, 01 Jan 2020 12:37:20 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Scott wrote:
When the ring main system was introduced (in 1947, I believe), the
correct fuse was used for each appliance. Why have we moved away from
this commonsense arrangement and apparently degraded a safety feature?

Because to know what the correct size fuse is, you'd need to know the
cable size. Somewhat easier with removable plugs, but guesswork with
moulded types.

How is it 'guesswork'? The manufacturer must know when they select
the fuse.

And perhaps most only want to get the thing working again, so will fit any
fuse they have to hand, or can buy easily. Most likely 13 amp.

Okay, but any sensible person would replace like for like. You could
say the same about 3A fuses. By your logic all electrical appliances
should be fitted with a 13A cable just in case someone decides to fit
a 13A fuse at a later stage.

Which is exactly what they do...

Note "13A cable" has no meaning in this sense. Since we are talking
about fault current situations and not continuous current handling
capacity. i.e. you will need a flex with at least 1.5mm^2 conductors to
carry 13A continuously. However a 0.5mm^2 flex may still be adequately
protected by a 13A fuse while carrying 150A of fault current.

What matters, is will the cable survive long enough without damage to
open the protective device. To know that you can do some arithmetic to
prove it.

For example, say you have a device with 1.8m of lead, and the flex has
0.5mm^2 CSA conductors. Lets assume its protected by a 13A fuse, and the
plug is in the furthest socket from the consumer unit on the circuit. To
make matters worse, let's assume the circuit itself only just meats the
maximum allowable earth loop impedance at that socket for a circuit
protected by a B32 MCB.

So let's take the circuit earth loop impedance at the socket as 1.37
Ohms[1].

We can take the loop impedance of the flex at around 87 mOhms/m, or 0.16
Ohms total. So if we add those, we get a total of 1.53 Ohms at the
appliance end of the "3A" flex.

So if we have a fault right at the appliance end, that will give a
prospective fault current of around 230 / 1.53 = 150A

Now we look at the fusing time for a 13A BS1362 fuse[2]. At 150A that's
nicely down in the 0.01 second range or less. So the last step is to
work out what the minimum cross sectional area of cable is needed to
survive that 150A of fault current for the duration. We can get this
using the adiabatic equation [3]:

s = sqrt( I^2 x t ) / k

where k is a constant dictated by the flex construction - we will take
it as 115 for a PVC flex. Plug the numbers in and we get:

s = sqrt( 150^2 x 0.01 ) / 115 = 0.13 mm^2

Hence we can conclude that our 0.5mm^2 CSA conductor flex is plenty
large enough to withstand the fault when protected by a 13A fuse.







[1]
http://wiki.diyfaq.org.uk/index.php/...Loop_Impedance


[2] http://wiki.diyfaq.org.uk/index.php/...FusingTime.png

[3]
http://wiki.diyfaq.org.uk/index.php/...diabatic_Check


--
Cheers,

John.

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On 01/01/2020 14:54, Scott wrote:
On Wed, 1 Jan 2020 14:39:45 +0000, Mike Clarke
wrote:

On 01/01/2020 13:07, Scott wrote:

Okay, but any sensible person would replace like for like. You could
say the same about 3A fuses.

That works on the assumption that most people are sensible.

There are many who would happily keep trying the next larger size fuse
until it 'worked'.

So all appliances are designed to be safe with a 13 amp fuse?

Yes

The flex on the lamp I bought from John Lewis does not look to me that it
could carry 13 amps but I could be wrong.

See the example I posted higher up the thread.

Contrary to common expectations, that flex is likely to be
conservatively oversized when protected by a 13A fuse.

Fuses can be called upon to provide fault current protection and/or
overload protection.

In the case of a lamp there is no likely or plausible situation that
would result in a significant and prolonged overload, since the largest
lamp it is designed to take would probably be a 100W incandescent bulb,
and that has a maximum draw of under half an amp.

So the fuse only has to worry about fault protection.

(also remember, if you plug that lamp in Germany, it will have only a
16A MCB in the consumer unit protecting it)

I won't be trying it out.

If you read up on the concepts of fault currents as opposed to overload
current, you might be reassured.

Fuses can be used to provide protection for either, but in most cases[1]
for a modern appliance they are only required to provide protection
against fault currents. (The appliance itself should include any
protection required to mitigate against for overload current, should
that be necessary)

http://wiki.diyfaq.org.uk/index.php/...oad_curre nts

[1] Once exception being multi socket extension leads.

--
Cheers,

John.

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On 01/01/2020 22:44, wrote:
On Wednesday, 1 January 2020 14:54:33 UTC, Scott wrote:
On Wed, 1 Jan 2020 14:39:45 +0000, Mike Clarke
wrote:
On 01/01/2020 13:07, Scott wrote:

Okay, but any sensible person would replace like for like. You could
say the same about 3A fuses.

That works on the assumption that most people are sensible.

There are many who would happily keep trying the next larger size fuse
until it 'worked'.

So all appliances are designed to be safe with a 13 amp fuse? The

no, though it's often said. Most is though.

The usual "problem" appliances are older ones that were intended for the
UK market only (and hence might include the plug fuse in the design of
their protection), or ones where the user has replaced or extended the
flex.

I agree that using the "right" fuse rather than always 13A is "better",
and I do it myself, however you also have to accept that you can't rely
everyone doing (or even being able to do) this.


--
Cheers,

John.

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On 03/01/2020 14:26, Dave Plowman (News) wrote:
In article ,
wrote:
And perhaps most only want to get the thing working again, so will fit
any fuse they have to hand, or can buy easily. Most likely 13 amp.

The correct fuse doesn't depend on cable size at all, it depends on the
load ie the appliance.

********. The fuse in a plug is only there to protect the cable. If the
appliance needs a fuse it will be in or on it.

Although NT could have worded that better, what he is saying is a
reasonable assessment if you start from the principle that any modern
appliance will have a flex fitted that will still fail safe when plugged
into a 16A protected circuit with no additional fusing, as would be the
case in the rest of Europe.

Then the fuse selected (if one is not just defaulting to 13A) will then
depend on the appliance load. E.g it would not be appropriate to fit a
3A fuse to the plug of your Washing Machine or Kettle.


--
Cheers,

John.

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\================================================= ================/

On 03/01/2020 16:15, Scott wrote:
On Fri, 03 Jan 2020 14:26:51 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
wrote:
And perhaps most only want to get the thing working again, so will fit
any fuse they have to hand, or can buy easily. Most likely 13 amp.

The correct fuse doesn't depend on cable size at all, it depends on the
load ie the appliance.

********. The fuse in a plug is only there to protect the cable. If the
appliance needs a fuse it will be in or on it.

What appliances do not need a fuse?

A table lamp would be a resonable example. No typical use case where it
could cause an overload. So all you need worry about is fault protection
for the cable.

(There are times you can even quite legitimately wire a fixed circuit
without including overload protection[1])

[1]
http://wiki.diyfaq.org.uk/index.php/...istics_of_load



--
Cheers,

John.

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In article ,
John Rumm wrote:
On 03/01/2020 14:26, Dave Plowman (News) wrote:
In article ,
wrote:
And perhaps most only want to get the thing working again, so will fit
any fuse they have to hand, or can buy easily. Most likely 13 amp.

The correct fuse doesn't depend on cable size at all, it depends on
the load ie the appliance.

********. The fuse in a plug is only there to protect the cable. If
the appliance needs a fuse it will be in or on it.

Although NT could have worded that better, what he is saying is a
reasonable assessment if you start from the principle that any modern
appliance will have a flex fitted that will still fail safe when plugged
into a 16A protected circuit with no additional fusing, as would be the
case in the rest of Europe.

Correct.

Then the fuse selected (if one is not just defaulting to 13A) will then
depend on the appliance load. E.g it would not be appropriate to fit a
3A fuse to the plug of your Washing Machine or Kettle.

But perfectly safe.

If the internals of a device need protection by a fuse - like many
electronic devices, it will be done so at the device itself - and not rely
on the plug fuse. Becuase virtually nothing is made for the UK only, and
very few countries have plug top fuses.

--
*Yes, I am an agent of Satan, but my duties are largely ceremonial

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

On 11/01/2020 15:06, Dave Plowman (News) wrote:
In article ,
John Rumm wrote:
On 03/01/2020 14:26, Dave Plowman (News) wrote:
In article ,
wrote:
And perhaps most only want to get the thing working again, so will fit
any fuse they have to hand, or can buy easily. Most likely 13 amp.

The correct fuse doesn't depend on cable size at all, it depends on
the load ie the appliance.

********. The fuse in a plug is only there to protect the cable. If
the appliance needs a fuse it will be in or on it.

Although NT could have worded that better, what he is saying is a
reasonable assessment if you start from the principle that any modern
appliance will have a flex fitted that will still fail safe when plugged
into a 16A protected circuit with no additional fusing, as would be the
case in the rest of Europe.

Correct.

Then the fuse selected (if one is not just defaulting to 13A) will then
depend on the appliance load. E.g it would not be appropriate to fit a
3A fuse to the plug of your Washing Machine or Kettle.

But perfectly safe.

Safe yup, but will also blow the fuse in short order...

If the internals of a device need protection by a fuse - like many
electronic devices, it will be done so at the device itself - and not rely
on the plug fuse. Becuase virtually nothing is made for the UK only, and
very few countries have plug top fuses.

Although quite a few (mostly former colonies and dependencies) have
pinched ours.


--
Cheers,

John.

/================================================== ===============\
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On Saturday, 11 January 2020 13:33:16 UTC, John Rumm wrote:
On 01/01/2020 14:08, Scott wrote:
On Wed, 1 Jan 2020 05:21:54 -0800 (PST),
wrote:
On Monday, 30 December 2019 22:12:42 UTC, tabby wrote:

Leads were often very thin, basically what we now call speaker wire.
Using under 3A fuses is wise if such wire is used.

Leads were also longer as people had fewer sockets. Remember the days you'd get a good 2 or 3 yards of flex on a table lamp.

Now all EU appliances are supposed to be okay with unfused plugs as that's normal in Europe, and leads are shorter to provide less resistance so a higher rated fuse/MCB blows quickly enough.

Lucky Golden Hedgehog leads from China are still on the thin side though.

If the purpose of the fuse is to protect the flex (as is often said),
does this mean all flexes can cope with 16 amps (European radial
circuit)?

Yup, that's the general idea... In most countries the option to protect
the flex at less than 16A is not usually available, so specifying the
maximum earth loop impedance of the lead is all you can do. Hence why
1.8m of 0.5mm^2 flex is common.

(whether actually true for some of the more dubious ebay tat etc is
another mater)

0.5mm2 is not suitable for 16A loads. It will carry far more during brief faults, but not for long.


NT

On Saturday, 11 January 2020 14:40:09 UTC, John Rumm wrote:
On 01/01/2020 22:44, tabbypurr wrote:
On Wednesday, 1 January 2020 14:54:33 UTC, Scott wrote:
On Wed, 1 Jan 2020 14:39:45 +0000, Mike Clarke
wrote:
On 01/01/2020 13:07, Scott wrote:

Okay, but any sensible person would replace like for like. You could
say the same about 3A fuses.

That works on the assumption that most people are sensible.

There are many who would happily keep trying the next larger size fuse
until it 'worked'.

So all appliances are designed to be safe with a 13 amp fuse? The

no, though it's often said. Most is though.

The usual "problem" appliances are older ones that were intended for the
UK market only (and hence might include the plug fuse in the design of
their protection), or ones where the user has replaced or extended the
flex.

I agree that using the "right" fuse rather than always 13A is "better",
and I do it myself, however you also have to accept that you can't rely
everyone doing (or even being able to do) this.

It's mainly old stuff, extension leads & many Chinese imports that need under 13A fusing. Wherever my 1937 set was sold it didn't come with any fusing or overload protection, and the radial mains wiring sometimes supplied suitable protection, sometimes didn't. That just how things were then. It was common knowledge in the 30s that leaving appliances on unattended caused many fires and was a lousy thing to do.

The considerable quantity of iffy Chinese goods, extension leads, and to a lesser extend old gear makes the advice that a 13A fuse is good for anything poor advice. But yes, we hear it a lot from people that should know better.

On 12/01/2020 18:35, wrote:
On Saturday, 11 January 2020 13:33:16 UTC, John Rumm wrote:
On 01/01/2020 14:08, Scott wrote:
On Wed, 1 Jan 2020 05:21:54 -0800 (PST),
wrote:
On Monday, 30 December 2019 22:12:42 UTC, tabby wrote:

Leads were often very thin, basically what we now call speaker wire.
Using under 3A fuses is wise if such wire is used.

Leads were also longer as people had fewer sockets. Remember the days you'd get a good 2 or 3 yards of flex on a table lamp.

Now all EU appliances are supposed to be okay with unfused plugs as that's normal in Europe, and leads are shorter to provide less resistance so a higher rated fuse/MCB blows quickly enough.

Lucky Golden Hedgehog leads from China are still on the thin side though.

If the purpose of the fuse is to protect the flex (as is often said),
does this mean all flexes can cope with 16 amps (European radial
circuit)?

Yup, that's the general idea... In most countries the option to protect
the flex at less than 16A is not usually available, so specifying the
maximum earth loop impedance of the lead is all you can do. Hence why
1.8m of 0.5mm^2 flex is common.

(whether actually true for some of the more dubious ebay tat etc is
another mater)

0.5mm2 is not suitable for 16A loads. It will carry far more during brief faults, but not for long.

I was not suggesting it was. I was saying that it *is* in most cases
however adequately protected from fault currents by a 16A MCB.



--
Cheers,

John.

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

On 12/01/2020 18:44, wrote:
On Saturday, 11 January 2020 14:40:09 UTC, John Rumm wrote:
On 01/01/2020 22:44, tabbypurr wrote:
On Wednesday, 1 January 2020 14:54:33 UTC, Scott wrote:
On Wed, 1 Jan 2020 14:39:45 +0000, Mike Clarke
wrote:
On 01/01/2020 13:07, Scott wrote:

Okay, but any sensible person would replace like for like.
You could say the same about 3A fuses.

That works on the assumption that most people are sensible.

There are many who would happily keep trying the next larger
size fuse until it 'worked'.

So all appliances are designed to be safe with a 13 amp fuse?
The

no, though it's often said. Most is though.

The usual "problem" appliances are older ones that were intended
for the UK market only (and hence might include the plug fuse in
the design of their protection), or ones where the user has
replaced or extended the flex.

I agree that using the "right" fuse rather than always 13A is
"better", and I do it myself, however you also have to accept that
you can't rely everyone doing (or even being able to do) this.

It's mainly old stuff, extension leads & many Chinese imports that
need under 13A fusing. Wherever my 1937 set was sold it didn't come
with any fusing or overload protection, and the radial mains wiring
sometimes supplied suitable protection, sometimes didn't. That just
how things were then. It was common knowledge in the 30s that leaving
appliances on unattended caused many fires and was a lousy thing to
do.

The considerable quantity of iffy Chinese goods, extension leads, and
to a lesser extend old gear makes the advice that a 13A fuse is good
for anything poor advice. But yes, we hear it a lot from people that
should know better.

I think you are missing the point. It is not that one would advise a
*user* to fit a 13A fuse regardless, one must insist that a *designer*
ensures the product will fail safe if they do.


--
Cheers,

John.

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

In article ,
wrote:
It's mainly old stuff, extension leads & many Chinese imports that need
under 13A fusing. Wherever my 1937 set was sold it didn't come with any
fusing or overload protection, and the radial mains wiring sometimes
supplied suitable protection, sometimes didn't. That just how things
were then. It was common knowledge in the 30s that leaving appliances on
unattended caused many fires and was a lousy thing to do.

I hope you're not suggesting the correct fuse will always stop something
catching fire?

The considerable quantity of iffy Chinese goods, extension leads, and to
a lesser extend old gear makes the advice that a 13A fuse is good for
anything poor advice. But yes, we hear it a lot from people that should
know better.

The best advice would be to junk any extension lead which isn't protected
by a 13 amp fuse. And if old gear isn't protected by its own correct type
of fuse, either junk it or fit one.

Anything else is simply bad practice.

--
*Experience is something you don't get until just after you need it *

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

On Mon, 13 Jan 2020 11:14:00 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
wrote:
It's mainly old stuff, extension leads & many Chinese imports that need
under 13A fusing. Wherever my 1937 set was sold it didn't come with any
fusing or overload protection, and the radial mains wiring sometimes
supplied suitable protection, sometimes didn't. That just how things
were then. It was common knowledge in the 30s that leaving appliances on
unattended caused many fires and was a lousy thing to do.

I hope you're not suggesting the correct fuse will always stop something
catching fire?

The considerable quantity of iffy Chinese goods, extension leads, and to
a lesser extend old gear makes the advice that a 13A fuse is good for
anything poor advice. But yes, we hear it a lot from people that should
know better.

The best advice would be to junk any extension lead which isn't protected
by a 13 amp fuse. And if old gear isn't protected by its own correct type
of fuse, either junk it or fit one.

What about reducing the fuse to 10 amps to create an added margin of
safety (or even 5 amps if it is only used for electronic equipment)?

On Monday, 13 January 2020 12:24:35 UTC, Scott wrote:
On Mon, 13 Jan 2020 11:14:00 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
wrote:
It's mainly old stuff, extension leads & many Chinese imports that need
under 13A fusing. Wherever my 1937 set was sold it didn't come with any
fusing or overload protection, and the radial mains wiring sometimes
supplied suitable protection, sometimes didn't. That just how things
were then. It was common knowledge in the 30s that leaving appliances on
unattended caused many fires and was a lousy thing to do.

I hope you're not suggesting the correct fuse will always stop something
catching fire?

The considerable quantity of iffy Chinese goods, extension leads, and to
a lesser extend old gear makes the advice that a 13A fuse is good for
anything poor advice. But yes, we hear it a lot from people that should
know better.

The best advice would be to junk any extension lead which isn't protected
by a 13 amp fuse. And if old gear isn't protected by its own correct type
of fuse, either junk it or fit one.

What about reducing the fuse to 10 amps to create an added margin of
safety (or even 5 amps if it is only used for electronic equipment)?

As the current through a fuse rises so does the temperature, and as a 5 amp
fuse can carry at least 7 amps for quite a while the temerpature of the fuse will rise and may even become hot, and that will cause the plug to become hot
which might start a fire or cause other problems of expantion and contraction.

On Monday, 13 January 2020 11:22:19 UTC, Dave Plowman (News) wrote:

The best advice would be to junk any extension lead which isn't protected
by a 13 amp fuse.

How can an extension lead (in the UK) not have a fused plug?

John

On Monday, 13 January 2020 13:49:48 UTC, wrote:
On Monday, 13 January 2020 11:22:19 UTC, Dave Plowman (News) wrote:

The best advice would be to junk any extension lead which isn't protected
by a 13 amp fuse.

How can an extension lead (in the UK) not have a fused plug?

John

Not strictly an extension cable, but an IEC lead to a monitor, just a few feet away from me in the UK, is unfused. Sure, any approved Schuko to 13A adaptor would have a fuse but the lead itself doesn't.

On Mon, 13 Jan 2020 05:42:06 -0800 (PST), whisky-dave
wrote:

On Monday, 13 January 2020 12:24:35 UTC, Scott wrote:
On Mon, 13 Jan 2020 11:14:00 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
wrote:
It's mainly old stuff, extension leads & many Chinese imports that need
under 13A fusing. Wherever my 1937 set was sold it didn't come with any
fusing or overload protection, and the radial mains wiring sometimes
supplied suitable protection, sometimes didn't. That just how things
were then. It was common knowledge in the 30s that leaving appliances on
unattended caused many fires and was a lousy thing to do.

I hope you're not suggesting the correct fuse will always stop something
catching fire?

The considerable quantity of iffy Chinese goods, extension leads, and to
a lesser extend old gear makes the advice that a 13A fuse is good for
anything poor advice. But yes, we hear it a lot from people that should
know better.

The best advice would be to junk any extension lead which isn't protected
by a 13 amp fuse. And if old gear isn't protected by its own correct type
of fuse, either junk it or fit one.

What about reducing the fuse to 10 amps to create an added margin of
safety (or even 5 amps if it is only used for electronic equipment)?

As the current through a fuse rises so does the temperature, and as a 5 amp
fuse can carry at least 7 amps for quite a while the temerpature of the fuse will rise and may even become hot, and that will cause the plug to become hot
which might start a fire or cause other problems of expantion and contraction.

True. That's why I suggested 5 amps rather than 2 or 3 amps, which
might be enough. Do you support the +50% rule?

In article ,
wrote:
On Monday, 13 January 2020 11:22:19 UTC, Dave Plowman (News) wrote:

The best advice would be to junk any extension lead which isn't protected
by a 13 amp fuse.

How can an extension lead (in the UK) not have a fused plug?

13A fused.

Actually, I have an extension lead, semi-permanently installed with a 2A
fuse. It was fitted to run a set of Christmas tree lights and used a
comparatively small cable to make it less obtrustive. If anyone was
foolish enought to plug a big load into it, the fuse would blow. Fuse
protecting tehncable.

John

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

On Sunday, 12 January 2020 22:11:44 UTC, John Rumm wrote:
On 12/01/2020 18:44, tabbypurr wrote:
On Saturday, 11 January 2020 14:40:09 UTC, John Rumm wrote:
On 01/01/2020 22:44, tabbypurr wrote:
On Wednesday, 1 January 2020 14:54:33 UTC, Scott wrote:
On Wed, 1 Jan 2020 14:39:45 +0000, Mike Clarke
wrote:
On 01/01/2020 13:07, Scott wrote:

Okay, but any sensible person would replace like for like.
You could say the same about 3A fuses.

That works on the assumption that most people are sensible.

There are many who would happily keep trying the next larger
size fuse until it 'worked'.

So all appliances are designed to be safe with a 13 amp fuse?
The

no, though it's often said. Most is though.

The usual "problem" appliances are older ones that were intended
for the UK market only (and hence might include the plug fuse in
the design of their protection), or ones where the user has
replaced or extended the flex.

I agree that using the "right" fuse rather than always 13A is
"better", and I do it myself, however you also have to accept that
you can't rely everyone doing (or even being able to do) this.

It's mainly old stuff, extension leads & many Chinese imports that
need under 13A fusing. Wherever my 1937 set was sold it didn't come
with any fusing or overload protection, and the radial mains wiring
sometimes supplied suitable protection, sometimes didn't. That just
how things were then. It was common knowledge in the 30s that leaving
appliances on unattended caused many fires and was a lousy thing to
do.

The considerable quantity of iffy Chinese goods, extension leads, and
to a lesser extend old gear makes the advice that a 13A fuse is good
for anything poor advice. But yes, we hear it a lot from people that
should know better.

I think you are missing the point. It is not that one would advise a
*user* to fit a 13A fuse regardless, one must insist that a *designer*
ensures the product will fail safe if they do.

Generally true for new products, if not the point.


NT

On Monday, 13 January 2020 11:22:19 UTC, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:

It's mainly old stuff, extension leads & many Chinese imports that need
under 13A fusing. Wherever my 1937 set was sold it didn't come with any
fusing or overload protection, and the radial mains wiring sometimes
supplied suitable protection, sometimes didn't. That just how things
were then. It was common knowledge in the 30s that leaving appliances on
unattended caused many fires and was a lousy thing to do.

I hope you're not suggesting the correct fuse will always stop something
catching fire?

https://www.nhs.uk/conditions/dementia/diagnosis-tests/


The considerable quantity of iffy Chinese goods, extension leads, and to
a lesser extend old gear makes the advice that a 13A fuse is good for
anything poor advice. But yes, we hear it a lot from people that should
know better.

The best advice would be to junk any extension lead which isn't protected
by a 13 amp fuse. And if old gear isn't protected by its own correct type
of fuse, either junk it or fit one.

Anything else is simply bad practice.

If you were in charge of my electricals you'd be sacked.

wrote:

How can an extension lead (in the UK) not have a fused plug?

Plus many older ones had a 13A fuse in an carrier of the extension block
itself (I see a *few* still do).

In article ,
Scott wrote:
The best advice would be to junk any extension lead which isn't
protected by a 13 amp fuse. And if old gear isn't protected by its own
correct type of fuse, either junk it or fit one.

What about reducing the fuse to 10 amps to create an added margin of
safety (or even 5 amps if it is only used for electronic equipment)?

Because of the chance of someone else using that piece of equipment. Maybe
even in the distant future.

--
*Toilet stolen from police station. Cops have nothing to go on.

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

In article ,
wrote:
On Monday, 13 January 2020 11:22:19 UTC, Dave Plowman (News) wrote:

The best advice would be to junk any extension lead which isn't
protected by a 13 amp fuse.

How can an extension lead (in the UK) not have a fused plug?

Was the 13 amp fuse bit beyond you?

--
*Why is it that most nudists are people you don't want to see naked?*

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

In article ,
charles wrote:
In article ,
wrote:
On Monday, 13 January 2020 11:22:19 UTC, Dave Plowman (News) wrote:

The best advice would be to junk any extension lead which isn't protected
by a 13 amp fuse.

How can an extension lead (in the UK) not have a fused plug?

13A fused.

Actually, I have an extension lead, semi-permanently installed with a 2A
fuse. It was fitted to run a set of Christmas tree lights and used a
comparatively small cable to make it less obtrustive. If anyone was
foolish enought to plug a big load into it, the fuse would blow. Fuse
protecting tehncable.

Until someone else fits it with a 13 amp fuse. ;-)

--
*If you must choose between two evils, pick the one you've never tried before

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

On Monday, 13 January 2020 14:11:30 UTC, Scott wrote:
On Mon, 13 Jan 2020 05:42:06 -0800 (PST), whisky-dave
wrote:

On Monday, 13 January 2020 12:24:35 UTC, Scott wrote:
On Mon, 13 Jan 2020 11:14:00 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
wrote:
It's mainly old stuff, extension leads & many Chinese imports that need
under 13A fusing. Wherever my 1937 set was sold it didn't come with any
fusing or overload protection, and the radial mains wiring sometimes
supplied suitable protection, sometimes didn't. That just how things
were then. It was common knowledge in the 30s that leaving appliances on
unattended caused many fires and was a lousy thing to do.

I hope you're not suggesting the correct fuse will always stop something
catching fire?

The considerable quantity of iffy Chinese goods, extension leads, and to
a lesser extend old gear makes the advice that a 13A fuse is good for
anything poor advice. But yes, we hear it a lot from people that should
know better.

The best advice would be to junk any extension lead which isn't protected
by a 13 amp fuse. And if old gear isn't protected by its own correct type
of fuse, either junk it or fit one.

What about reducing the fuse to 10 amps to create an added margin of
safety (or even 5 amps if it is only used for electronic equipment)?

As the current through a fuse rises so does the temperature, and as a 5 amp
fuse can carry at least 7 amps for quite a while the temerpature of the fuse will rise and may even become hot, and that will cause the plug to become hot
which might start a fire or cause other problems of expantion and contraction.

True. That's why I suggested 5 amps rather than 2 or 3 amps, which
might be enough. Do you support the +50% rule?

No.

When you don;t know what your lead might be connected to you should
go by the latest regs not invent your own, especailly in a workplace.

On Mon, 13 Jan 2020 14:44:36 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Scott wrote:
The best advice would be to junk any extension lead which isn't
protected by a 13 amp fuse. And if old gear isn't protected by its own
correct type of fuse, either junk it or fit one.

What about reducing the fuse to 10 amps to create an added margin of
safety (or even 5 amps if it is only used for electronic equipment)?

Because of the chance of someone else using that piece of equipment. Maybe
even in the distant future.

That's a good point, actually, especially if the extension could
continue working with the fuse running hot. I'll change them back to
13A.

I especially like your footnote (now disappeared) which I can pass on
to certain people :-) .

In article ,
wrote:
The best advice would be to junk any extension lead which isn't
protected by a 13 amp fuse. And if old gear isn't protected by its own
correct type of fuse, either junk it or fit one.

Anything else is simply bad practice.

If you were in charge of my electricals you'd be sacked.

If I were in charge of your electricals, you'd not be using anything
fundamentally unsafe.

But since I'm not, carry on as you are.

--
*I'm not a paranoid, deranged millionaire. Dammit, I'm a billionaire.

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

In article ,
Scott wrote:
On Mon, 13 Jan 2020 14:44:36 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Scott wrote:
The best advice would be to junk any extension lead which isn't
protected by a 13 amp fuse. And if old gear isn't protected by its own
correct type of fuse, either junk it or fit one.

What about reducing the fuse to 10 amps to create an added margin of
safety (or even 5 amps if it is only used for electronic equipment)?

Because of the chance of someone else using that piece of equipment. Maybe
even in the distant future.

That's a good point, actually, especially if the extension could
continue working with the fuse running hot. I'll change them back to
13A.

If that extension lead is of sufficient gauge to blow a 13 amp fuse in
event of a fault, there is no reason not to fit a smaller fuse if you want.

What I'd not have is a lead made with undersized cable which could melt
before blowing a 13 amp fuse. And, of course, the minimum size of cable
needed varies with the length of the extension lead.

I especially like your footnote (now disappeared) which I can pass on
to certain people :-) .

There will be a different one this time. ;-)

--
*They call it PMS because Mad Cow Disease was already taken.

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

On 13/01/2020 12:24, Scott wrote:
On Mon, 13 Jan 2020 11:14:00 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
wrote:
It's mainly old stuff, extension leads & many Chinese imports that need
under 13A fusing. Wherever my 1937 set was sold it didn't come with any
fusing or overload protection, and the radial mains wiring sometimes
supplied suitable protection, sometimes didn't. That just how things
were then. It was common knowledge in the 30s that leaving appliances on
unattended caused many fires and was a lousy thing to do.

I hope you're not suggesting the correct fuse will always stop something
catching fire?

The considerable quantity of iffy Chinese goods, extension leads, and to
a lesser extend old gear makes the advice that a 13A fuse is good for
anything poor advice. But yes, we hear it a lot from people that should
know better.

The best advice would be to junk any extension lead which isn't protected
by a 13 amp fuse. And if old gear isn't protected by its own correct type
of fuse, either junk it or fit one.

What about reducing the fuse to 10 amps to create an added margin of
safety (or even 5 amps if it is only used for electronic equipment)?

With some 4 way leads made from Chinesium, its becoming quite common for
them to be supplied that way (i.e. with 10A fuse pre-fitted), since it
has been demonstrated many do not fare well when subjected to a moderate
overload on a 13A fuse (e.g. a continuous load of 18A or so).


--
Cheers,

John.

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

In article ,
John Rumm wrote:
What about reducing the fuse to 10 amps to create an added margin of
safety (or even 5 amps if it is only used for electronic equipment)?

With some 4 way leads made from Chinesium, its becoming quite common for
them to be supplied that way (i.e. with 10A fuse pre-fitted), since it
has been demonstrated many do not fare well when subjected to a moderate
overload on a 13A fuse (e.g. a continuous load of 18A or so).

It does rather prove the point. No-one with any sense would load up an
extension lead to 18 amps. They would likely be the same person who would
replace a 2 amp fuse in a plug top with a 13 amp one - because after all
it gets it working again, the only important thing?

--
*Why isn't there a special name for the back of your knee?

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

On Mon, 13 Jan 2020 15:37:10 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Scott wrote:
On Mon, 13 Jan 2020 14:44:36 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Scott wrote:
The best advice would be to junk any extension lead which isn't
protected by a 13 amp fuse. And if old gear isn't protected by its own
correct type of fuse, either junk it or fit one.

What about reducing the fuse to 10 amps to create an added margin of
safety (or even 5 amps if it is only used for electronic equipment)?

Because of the chance of someone else using that piece of equipment. Maybe
even in the distant future.

That's a good point, actually, especially if the extension could
continue working with the fuse running hot. I'll change them back to
13A.

If that extension lead is of sufficient gauge to blow a 13 amp fuse in
event of a fault, there is no reason not to fit a smaller fuse if you want.

I thought your reasoning was that if you overloaded the fuse it might
keep working but get very hot and damage the plug (though I thought
they were packed with sand to prevent that happening). .

What I'd not have is a lead made with undersized cable which could melt
before blowing a 13 amp fuse. And, of course, the minimum size of cable
needed varies with the length of the extension lead.

I especially like your footnote (now disappeared) which I can pass on
to certain people :-) .

There will be a different one this time. ;-)

Yes, but I can go back in history :-)

On 09/01/2020 16:12, Dave Plowman (News) wrote:
In article ,
Steve Walker wrote:
I thought that nowadays you have to hold the button down to close the
power window. Only opening goes all the way down with one press.

No, my Zafira B has auto closing on all windows.

So did my last three cars.


So does the Scudo and Skoda (well not the passenger side of the Scudo as
the switch broke last month). But the windows back off if your put your
fingers in them.

You can override that function by keeping your finger on the button.
Handy when closing a window with ice on it or travelling at speed.

--
Adam

On 13/01/2020 14:22, charles wrote:
In article ,
wrote:
On Monday, 13 January 2020 11:22:19 UTC, Dave Plowman (News) wrote:

The best advice would be to junk any extension lead which isn't protected
by a 13 amp fuse.

How can an extension lead (in the UK) not have a fused plug?

13A fused.

Actually, I have an extension lead, semi-permanently installed with a 2A
fuse. It was fitted to run a set of Christmas tree lights and used a
comparatively small cable to make it less obtrustive. If anyone was
foolish enought to plug a big load into it, the fuse would blow. Fuse
protecting tehncable.

I have four very short (6") cables with a 13A socket on one end and an
unfused 5A plug on the other. Of course these the 5A sockets are
provided for switched lighting and are protected by the lighting MCB.
The reason for them is that when plugging Christmas lights in, most
these days are LED and come with 3-pin wall-warts and so need the 13A
socket. For the rest of the year, these leads reside in the Christmas
decorations box.

SteveW

On Mon, 13 Jan 2020 22:35:54 +0000, Steve Walker wrote:

I have four very short (6") cables with a 13A socket on one end and an
unfused 5A plug on the other.

I had at least one of those in my University of Essex study bedroom, as
they didn't provide 13 amp sockets.

Worse were the study bedrooms in Darwin College at Kent. They had a 2.5A
circuit breaker for the whole room, but located in the room. This wa
sbecause the wiring was installed at a time of high copper prices, as I
recall.



--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

On Monday, 13 January 2020 15:38:16 UTC, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:

The best advice would be to junk any extension lead which isn't
protected by a 13 amp fuse. And if old gear isn't protected by its own
correct type of fuse, either junk it or fit one.

Anything else is simply bad practice.

If you were in charge of my electricals you'd be sacked.

If I were in charge of your electricals, you'd not be using anything
fundamentally unsafe.

But since I'm not, carry on as you are.

you plainly have no ability to discern the safe from the unsafe. ICBA, this is too dumb.

On Monday, 13 January 2020 17:07:20 UTC, Dave Plowman (News) wrote:
In article ,
John Rumm wrote:

With some 4 way leads made from Chinesium, its becoming quite common for
them to be supplied that way (i.e. with 10A fuse pre-fitted), since it
has been demonstrated many do not fare well when subjected to a moderate
overload on a 13A fuse (e.g. a continuous load of 18A or so).

It does rather prove the point. No-one with any sense would load up an
extension lead to 18 amps. They would likely be the same person who would
replace a 2 amp fuse in a plug top with a 13 amp one - because after all
it gets it working again, the only important thing?

So welding is something else you also don't understand. Yawn.

In article ,
Bob Eager wrote:
On Mon, 13 Jan 2020 22:35:54 +0000, Steve Walker wrote:

I have four very short (6") cables with a 13A socket on one end and an
unfused 5A plug on the other.

I had at least one of those in my University of Essex study bedroom, as
they didn't provide 13 amp sockets.

Worse were the study bedrooms in Darwin College at Kent. They had a 2.5A
circuit breaker for the whole room, but located in the room. This wa
sbecause the wiring was installed at a time of high copper prices, as I
recall.

at boarding school, I had a two-way adaptor from the bayonet light fitting
which gave me a lead from which I could run my radio.

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

On Tue, 14 Jan 2020 08:38:08 +0000 (GMT), charles
wrote:

In article ,
Bob Eager wrote:
On Mon, 13 Jan 2020 22:35:54 +0000, Steve Walker wrote:

I have four very short (6") cables with a 13A socket on one end and an
unfused 5A plug on the other.

I had at least one of those in my University of Essex study bedroom, as
they didn't provide 13 amp sockets.

Worse were the study bedrooms in Darwin College at Kent. They had a 2.5A
circuit breaker for the whole room, but located in the room. This wa
sbecause the wiring was installed at a time of high copper prices, as I
recall.

at boarding school, I had a two-way adaptor from the bayonet light fitting
which gave me a lead from which I could run my radio.

I think irons used to run this way. An added benefit was that it was
particularly convenient to have the cord dropping from the ceiling. I
think we connected the Christmas lights by this method.