On 09/11/2012 10:46, wrote:
On Thursday, November 8, 2012 2:57:26 PM UTC, John Rumm wrote:
On 08/11/2012 13:53, Mike Tomlinson wrote:
In article ,
John Rumm writes

http://s833.beta.photobucket.com/use...erfeitFuse.mp4.


html

"We're sorry, we cannot find the page you requested."

http://www.bs1363.org.uk/counterfeit_fuse.mpeg

wow. Must have filled it with gunpowder rather than sand.
Na, just air... Shows you want a fault current (wiring regs
meaning) can do!


I'm not convinced. In decades past I've seen loads of fuses repaired
with bits of fusewire, or worse just a thin strand of copper wire.
The failure of such fuses was entirely tame, the downside was just
black deposits inside the plug, requiring a new plug. I've seen
plenty of glass fuses fail on mains too, and again nothing dramatic.

How could they create that clip? I suspect by bypassing the
protection of both incomer fuse and CU entirely, and picking an
unusually meaty (non)fuse, and passing the full 6kA through it,
perhaps at above mains voltage too. It sure looks like bs to me, but
not 1362.

Go search youtube for "arc flash" - even 240V supplies can be quite scary.




--
Cheers,

John.

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On 08/11/2012 22:22, The Other Mike wrote:
On Wed, 07 Nov 2012 22:44:35 +0000, John Rumm
wrote:

You want to see the bang with the counterfeit ones arriving with your
latest mains lead from China via ebay:

http://www.bs1363.org.uk/counterfeit_fuse.mpeg


Surely for fuses that should be bs1362.org.uk ?

The site as a whole is about plugs in general rather than fuses.


--
Cheers,

John.

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On 09/11/2012 16:55, whisky-dave wrote:

No I didn;t because I estimated that the switch on surge would be low
for this type of applience well low is respect of the fuse rating.

Fans will usually have some form of induction motor. Inrush of 5 to 9x
normal operating current is not uncommon for some of these. (a small
desk fan will probably be a shaded pole motor - these have less inrush IIRC)

How would you calculte the switch on surge if you needed to ? How
would you allow for this value in the fuse you choose ?.

In some cases by the type of fuse - when trying to use a fuse for close
protection, you have several versions of each rating available with
different time constants.



--
Cheers,

John.

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On 09/11/2012 16:29, polygonum wrote:
On 09/11/2012 13:57, Mike Tomlinson wrote:
In article ,
whisky-dave writes

True but how do you calculate the minimum fuse necessary, it's not
always that
easy.

Yes it is, you look at the appliance rating plate and if it's in watts
not amps, apply Ohm's law.

I can't help thinking that it would make sense for manufacturers to
include "use a 3A plug fuse" on the rating plate. We see so many
meaningless[1] symbols identifying all the standards it claims to follow
- why not a piece of potentially useful information?

Might pee off most of the other countries in the EU though...

(Bonus!)



--
Cheers,

John.

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On 09/11/2012 23:27, John Rumm wrote:
On 09/11/2012 16:29, polygonum wrote:
On 09/11/2012 13:57, Mike Tomlinson wrote:
In article ,
whisky-dave writes

True but how do you calculate the minimum fuse necessary, it's not
always that
easy.

Yes it is, you look at the appliance rating plate and if it's in watts
not amps, apply Ohm's law.

I can't help thinking that it would make sense for manufacturers to
include "use a 3A plug fuse" on the rating plate. We see so many
meaningless[1] symbols identifying all the standards it claims to follow
- why not a piece of potentially useful information?

Might pee off most of the other countries in the EU though...

(Bonus!)



:-)

Had thought of posting "Where a fused plug is required, use a 3A fuse" -
but thought the age old issue of language would make that a bit silly.
So kept it simple. I am sure our symbol-inventors can come up with
something suitable...

[[ 3A ]]

--
Rod

On Friday, November 9, 2012 8:20:01 PM UTC, bert wrote:
In message ,
meow2222 writes

Fusing on the neutral pole was banned here eons ago.
Snip

Fusing the neutral must be one of the most brainless ideas ever.

IIUC it was done because the neutral supply line couldnt be counted on to not be live. It would have made more sense, back when it was done, to use 2 different fuse values for each L/N pair, eg 15A and 20A, to help ensure that under normal polarity conditions it was the live that fused.


NT

On Friday, November 9, 2012 6:57:03 PM UTC, polygonum wrote:

flexes...

Not only short - but inflexible. Well, they do flex, but they don't
drape as they should. Got several things which are a pain to use simply
because of the flex.

Bring back string filled flex

NT

"whisky-dave" wrote in message
...

The fuses are designed for fault current, which means, as
one poster in the link stated a 3A and 13A will break as quick as each
other - on a fault.

really ?

He did.

A 3amp fuse will break as quick as a
13amp will iof you pass 15 amps through it I don;t think so.

Keep up sunshine.

I only scanned the link, but one poster I think was saying have all fuses
13A. So if he had a lamp with 0.25mm flex and 13A fuses he thinks he is
safe. OK on a lamp it is difficult to see how the current would be great
enough to melt the cable as the bulb would blow way before any current is
dangerous enough.

Unless somethijng shorts circuits the buld of course.

...and then the fuse breaks.

The secret? As fuses have dropped into 3A and 13A in common use (Only
specialist outlets sell anything else these days) never install flex that
is
rated less than 3A

Unless yuo need to.

Pay attention. Then you use fuses other than 3 or 13A

and fit correct sized fuse to protect the cable. The
cable should never be rated less than the fuse.

Some fit larger rated fuses because of surge.

Which is wrong.

If there is surge then fit
anti-surge fuses, not a large rated fuse.

Which is right. Good you are catching on.

A while ago I brought some 20mm 32ma slow-blow for a piece of euipment.

Good you are catching on.

On Friday, November 9, 2012 6:41:28 PM UTC, Mike Tomlinson wrote:
En el artículo ,

whisky-dave escribió:



If I wass using cvommon sense I;'d use teh lowest fuses I have which is a 1 amp,

but I use management sense which means 3 amp is chosen.



If by 'management sense' you mean common sense, then we're arguing about

precisely nothing :-)

Now we're talking about what you'r told to do by the regulations or managment that's in charge of your job, it is that simple.

Years ago we were told to check all plugs and replace any fuses that were wrong with the correct fuse whether it was 3, 5 10 13 amp.
Now wee not suppoosed to replace fuses where you need to open the plug up and if you do so you need teh aplince PAT'd before it cane be re-used .

So NO common sense is NOT the correct method.






--

(\_/)

(='.'=)

(")_(")

On Thursday, November 22, 2012 10:48:18 AM UTC, Doctor Drivel wrote:
"whisky-dave" wrote in message

...



The fuses are designed for fault current, which means, as

one poster in the link stated a 3A and 13A will break as quick as each

other - on a fault.



really ?



He did.



A 3amp fuse will break as quick as a

13amp will iof you pass 15 amps through it I don;t think so.



Keep up sunshine.

I've already passed you.




I only scanned the link, but one poster I think was saying have all fuses

13A. So if he had a lamp with 0.25mm flex and 13A fuses he thinks he is

safe. OK on a lamp it is difficult to see how the current would be great

enough to melt the cable as the bulb would blow way before any current is

dangerous enough.



Unless somethijng shorts circuits the buld of course.



..and then the fuse breaks.

Only if the fuse is of a lower rating than the cable.
you might fidn a 3 amp cable gets hot before the 13 amp fuse blows.



The secret? As fuses have dropped into 3A and 13A in common use (Only

specialist outlets sell anything else these days) never install flex that

is

rated less than 3A



Unless yuo need to.



Pay attention. Then you use fuses other than 3 or 13A

Which are availble.



and fit correct sized fuse to protect the cable. The

cable should never be rated less than the fuse.



Some fit larger rated fuses because of surge.



Which is wrong.

No it isn;t .


If there is surge then fit

anti-surge fuses, not a large rated fuse.



Which is right. Good you are catching on.

But you can't buy such fuses for the standard 3 pin plugs.



A while ago I brought some 20mm 32ma slow-blow for a piece of euipment.



Good you are catching on.

Yep I know what I'm doing you clearly don;t if yuo'd put a 5 amp fuse in a 1kw fire.

In article ,
whisky-dave wrote:
On Friday, November 9, 2012 6:41:28 PM UTC, Mike Tomlinson wrote:
En el artículo ,

whisky-dave escribió:



If I wass using cvommon sense I;'d use teh lowest fuses I have which
is a 1 amp,

but I use management sense which means 3 amp is chosen.



If by 'management sense' you mean common sense, then we're arguing about

precisely nothing :-)

Now we're talking about what you'r told to do by the regulations or
managment that's in charge of your job, it is that simple.

Years ago we were told to check all plugs and replace any fuses that were
wrong with the correct fuse whether it was 3, 5 10 13 amp. Now wee not
suppoosed to replace fuses where you need to open the plug up and if you
do so you need teh aplince PAT'd before it cane be re-used .

So NO common sense is NOT the correct method.

opening the plug and checking fusing and terminals is part of a PAT test.

--
From KT24

Using a RISC OS computer running v5.18

"whisky-dave" wrote in message
...

..and then the fuse breaks.

Only if the fuse is of a lower rating than the cable.
you might fidn a 3 amp cable gets hot before the 13 amp fuse blows.

Why you shoud pout in the correct fuse.

Some fit larger rated fuses because of surge.


Which is wrong.

No it isn;t .

IT IS dope! The fuse should never be great than the cable. If you have
surge get an anti-surge fuse.

A while ago I brought some 20mm 32ma slow-blow for a piece of
euipment.

Good you are catching on.

Yep I know what I'm doing

I know you do. You deliberately make electrical systems unsafe. You are
some sort of pychopath.

wrote in message
...

You're the only person I've ever heard describe pound shops as specialist
outlets.

This man is mad.

In article ,
charles wrote:
opening the plug and checking fusing and terminals is part of a PAT test.

But surely this can't be done in most cases?

--
*Can fat people go skinny-dipping?

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

In article ,
Doctor Drivel wrote:
IT IS dope! The fuse should never be great than the cable. If you have
surge get an anti-surge fuse.

Please give a supplier of such fuses that conform to the BS for 13 amp
plug fuses?

--
*I don't have a license to kill, but I do have a learner's permit.

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

In article ,
Dave Plowman (News) wrote:
In article ,
charles wrote:
opening the plug and checking fusing and terminals is part of a PAT
test.

But surely this can't be done in most cases?

be sensible, if it's a moulded on plug, you can't do that.

--
From KT24

Using a RISC OS computer running v5.18

Dave Plowman (News) wrote:
In article ,
Doctor Drivel wrote:
IT IS dope! The fuse should never be great than the cable. If you
have surge get an anti-surge fuse.

Please

This man needs to eff off.

On Thu, 22 Nov 2012 13:53:44 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Doctor Drivel wrote:
IT IS dope! The fuse should never be great than the cable. If you have
surge get an anti-surge fuse.

Please give a supplier of such fuses that conform to the BS for 13 amp
plug fuses?

Plantpot Fuses R Us ?

Once used a Farnell 60v 50A PSU that was wired to a normal 13A plugtop. On
startup after being in cold storage you needed a small handful of 13A fuses that
lasted about a few mains cycles so you could get enough charge in the smoothing
caps to reduce the inrush. Once you'd done that it worked ok. It wasn't a case
of reforming the caps as the were replaced, ideally it needed two plugs to the
ring


--

On Thursday, November 22, 2012 1:58:34 PM UTC, Dave Plowman (News) wrote:
In article ,
Doctor Drivel wrote:

IT IS dope! The fuse should never be great than the cable. If you have
surge get an anti-surge fuse.

Please give a supplier of such fuses that conform to the BS for 13 amp
plug fuses?

And the 32mA fuses Drivel recommended


NT

On 22/11/2012 12:41, Doctor Drivel wrote:

IT IS dope! The fuse should never be great than the cable. If you have
surge get an anti-surge fuse.

Let me help you with a translation for that. What dribble was trying to
say was:

The fuse should never have a greater rating than the fault withstand
current of the cable. If you have a high inrush surge to deal with, then
fit a 13A fuse since there is no such thing as a time delay BS1362 fuse,
and a 13A will give adequate fault protection anyway while withstanding
high inrush.

You're welcome.


--
Cheers,

John.

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

wrote in message
...

And the 32mA fuses Drivel recommended

He did? Wow.

"John Rumm" wrote in message
o.uk...
On 22/11/2012 12:41, Doctor Drivel wrote:

IT IS dope! The fuse should never be great than the cable. If you have
surge get an anti-surge fuse.

Let me help you with a translation for that.

snip drivel

On Thursday, November 22, 2012 12:41:01 PM UTC, Doctor Drivel wrote:
"whisky-dave" wrote in message

...



..and then the fuse breaks.



Only if the fuse is of a lower rating than the cable.

you might fidn a 3 amp cable gets hot before the 13 amp fuse blows.



Why you shoud pout in the correct fuse.

Yes exactly you put the correct fuse in not the 'calculated' value.



Some fit larger rated fuses because of surge.





Which is wrong.



No it isn;t .



IT IS dope! The fuse should never be great than the cable.


yes I know the plug fuse is to protect the cable.


If you have

surge get an anti-surge fuse.

You can't buy anti-surge fuses for standard 3 pin plugs.


A while ago I brought some 20mm 32ma slow-blow for a piece of

euipment.



Good you are catching on.



Yep I know what I'm doing



I know you do. You deliberately make electrical systems unsafe. You are

some sort of pychopath.

How would putting the correct fuse in make electrical systems unsafe ?
(unless the equipment was faulty or failed anyrequired test)

On Thursday, November 22, 2012 12:19:21 PM UTC, charles wrote:
In article ,

whisky-dave wrote:

On Friday, November 9, 2012 6:41:28 PM UTC, Mike Tomlinson wrote:

En el artículo ,



whisky-dave escribió:







If I wass using cvommon sense I;'d use teh lowest fuses I have which

is a 1 amp,



but I use management sense which means 3 amp is chosen.







If by 'management sense' you mean common sense, then we're arguing about



precisely nothing :-)



Now we're talking about what you'r told to do by the regulations or

managment that's in charge of your job, it is that simple.



Years ago we were told to check all plugs and replace any fuses that were

wrong with the correct fuse whether it was 3, 5 10 13 amp. Now wee not

suppoosed to replace fuses where you need to open the plug up and if you

do so you need teh aplince PAT'd before it cane be re-used .



So NO common sense is NOT the correct method.



opening the plug and checking fusing and terminals is part of a PAT test.

yes that's the point when PAT'ing equipment you test the equipemnt and any leads that power it. With the IEC leads it can be cheaper and more efficinet to buy a new lead rather than pay £1.49p to have one tested.
Unfortunalty some of our older equipment has dedicated leads so that's not an option.





--

From KT24



Using a RISC OS computer running v5.18

"whisky-dave" wrote in message
...

I know you do. You deliberately make electrical systems unsafe. You are
some sort of pychopath.

How would putting the correct fuse in make electrical systems unsafe ?


Read above.

On Friday, November 23, 2012 12:06:58 PM UTC, Doctor Drivel wrote:
"whisky-dave" wrote in message

...



I know you do. You deliberately make electrical systems unsafe. You are

some sort of pychopath.



How would putting the correct fuse in make electrical systems unsafe ?



Above what the Drivel ?



Read above.

wrote in message
...
On Friday, November 23, 2012 1:55:07 PM UTC, whisky-dave wrote:
On Friday, November 23, 2012 12:06:58 PM UTC, Doctor Drivel wrote:

Above what the Drivel ?

do yourself a favour and plonk him. You'll never get reason from Drivel.

You mean I will never agree with an idiot.

On 25/11/2012 22:47, Doctor Drivel wrote:

wrote in message
...
On Friday, November 23, 2012 1:55:07 PM UTC, whisky-dave wrote:
On Friday, November 23, 2012 12:06:58 PM UTC, Doctor Drivel wrote:

Above what the Drivel ?

do yourself a favour and plonk him. You'll never get reason from Drivel.

You mean I will never agree with an idiot.

Hmm. Do you agree with yourself?

--
Rod

In message , polygonum
writes
On 25/11/2012 22:47, Doctor Drivel wrote:

wrote in message
...
On Friday, November 23, 2012 1:55:07 PM UTC, whisky-dave wrote:
On Friday, November 23, 2012 12:06:58 PM UTC, Doctor Drivel wrote:

Above what the Drivel ?

do yourself a favour and plonk him. You'll never get reason from Drivel.

You mean I will never agree with an idiot.

Hmm. Do you agree with yourself?

Drivel and dIMM spend their time having arguments with each other

and then kissing and making up

if only D was a dog, eh?
--
geoff

"geoff" wrote in message
...
In message , polygonum
writes
On 25/11/2012 22:47, Doctor Drivel wrote:

wrote in message
...
On Friday, November 23, 2012 1:55:07 PM UTC, whisky-dave wrote:
On Friday, November 23, 2012 12:06:58 PM UTC, Doctor Drivel wrote:

Above what the Drivel ?

do yourself a favour and plonk him. You'll never get reason from
Drivel.

You mean I will never agree with an idiot.

Hmm. Do you agree with yourself?

Drivel and dIMM spend their time having arguments with each other

and then kissing and making up

if only D was a dog, eh?

Maxie, how are you? Are you still doing psychedelic things? Fantastic. Do
you have a psychedelic Paddy band now. Amazing. Only Maxie does these sorts
of things. What a man!

On 08/11/2012 07:57, harry wrote:
On Nov 7, 11:56 pm, Frank Erskine
wrote:
On Wed, 07 Nov 2012 22:26:06 +0000, Peter Crosland
wrote:

On 07/11/2012 18:40, David Robinson wrote:
Not my question, or belief, but found here...

http://forums.digitalspy.co.uk/showthread.php?t=1755197

Is there a counter-argument?

Only the terminally stupid would use a 13A fuse when a 3A is appropriate.

In the early days of colour TV I was told by a TV engineer that the
correct plug fuse for a CTV was 7A to allow for the switch-on current
surge of the degaussing circuitry.

I don't know whether or not "intermediate" BS1362 fuses such as 5A or
7A are still available.

In fact, was there not also a 1A BS1362 fuse, used for clock plugs,
but not shaver adaptors (or was it the other way round?)?

--
Frank Erskine

There was indeed. One was physically smaller than the plug fuse. You
found them in mains electric clock connectors. Of course, you never
see mains clocks any more except as radios.

Or Nixies

SteveW

On Wednesday, November 7, 2012 at 6:40:34 PM UTC, David Robinson wrote:
Not my question, or belief, but found here...

http://forums.digitalspy.co.uk/showthread.php?t=1755197


Is there a counter-argument?

Thanks,
David.

To "the fuse is there to protect the cable" ? Hmmm, that's rather to vague, and technically incorrect. I think you need to ask what are we protecting really, and I beg to differ that the fuse is there to protect the cable, here are some reasons why:

Really what we are protecting is ourselves and other property from electrocution and fire, The simple fact is that if the cable is overloaded then it will melt and cause a fire, it will then also short out the supply causing further risk. To illustrate lets consider the service fuse in your electricity supply, without it any short or overload would probably take out at least part of your street.
It's easy to forget that the fuse is there to protect against overload because in most cases it's blown due to a direct short, but if you are running a 3KW heater on a 5A lighting circuit with a 13A fuse, that wire is going to melt sooner or later, but even assuming it doesn't, over time the excess heat will make the plastic brittle and one day it will crack, perhaps when you pick up the cable! A 13A fuse will certainly protect a direct short an a 3A cable as it won't really have time to melt before the fuse blows, but if you want a demonstration of what can happen try dropping a some 13A stranded wire across a 12V car battery, make sure you aren't holding it and there is nothing combustable around though as the whole length will instantly burn all it's length before it vapourises- It's quite spectacular, yo might want to wear suitable eye protection as it could be quite bright.

On Friday, 18 November 2016 22:49:09 UTC, wrote:
On Wednesday, November 7, 2012 at 6:40:34 PM UTC, David Robinson wrote:
Not my question, or belief, but found here...

http://forums.digitalspy.co.uk/showthread.php?t=1755197


Is there a counter-argument?

Thanks,
David.

You're replying to a 4 year old discussion for some reason.

To "the fuse is there to protect the cable" ? Hmmm, that's rather to vague, and technically incorrect. I think you need to ask what are we protecting really, and I beg to differ that the fuse is there to protect the cable, here are some reasons why:

Really what we are protecting is ourselves and other property from electrocution and fire, The simple fact is that if the cable is overloaded then it will melt and cause a fire, it will then also short out the supply causing further risk.

That certainly isn't fact.

To illustrate lets consider the service fuse in your electricity supply, without it any short or overload would probably take out at least part of your street.
It's easy to forget that the fuse is there to protect against overload

maybe for strangely forgetful folk

because in most cases it's blown due to a direct short, but if you are running a 3KW heater on a 5A lighting circuit with a 13A fuse, that wire is going to melt sooner or later,

Rubbish. BTDT.

but even assuming it doesn't, over time the excess heat will make the plastic brittle and one day it will crack, perhaps when you pick up the cable! A 13A fuse will certainly protect a direct short an a 3A cable as it won't really have time to melt before the fuse blows, but if you want a demonstration of what can happen try dropping a some 13A stranded wire across a 12V car battery, make sure you aren't holding it and there is nothing combustable around though as the whole length will instantly burn all it's length before it vapourises- It's quite spectacular, yo might want to wear suitable eye protection as it could be quite bright.


It's all quite simple. 3A fuses aren't required for new goods that conform to the law, if extension leads aren't used. IOW in most cases 3A fuses are unnecessary. Now add the real life facts of old appliances, nonconforming goods, extension leads and daisy chained extension leads and it's easy to see why 3A fuses are still a smart idea.


NT

On 18/11/2016 22:49, wrote:
On Wednesday, November 7, 2012 at 6:40:34 PM UTC, David Robinson
wrote:
Not my question, or belief, but found here...

http://forums.digitalspy.co.uk/showthread.php?t=1755197


Is there a counter-argument?

Yup plenty ;-)

Thanks, David.

To "the fuse is there to protect the cable" ?

One needs to be specific about which fuse, and in what circumstance.

There are some circumstances where the primary of job of a fuse is to
provide fault protection to a cable. However there are other times it
may be required to provide overload protection (to a cable or an
appliance).

In this particular case it seems to be talking about the plug fuse on an
appliance lead. If one ignores some very old appliances, then its true
the only purpose of the fuse is for *fault* protection of the lead. If
the appliance needs overload protection, then it must include its own
internally.

(note this is a different situation from hard wired appliances that
don't have fitted flex and plug - there a manufacturer may require a
particular fuse rating in the supply)

Hmmm, that's rather to
vague, and technically incorrect. I think you need to ask what are we
protecting really, and I beg to differ that the fuse is there to
protect the cable, here are some reasons why:

Really what we are protecting is ourselves and other property from
electrocution and fire, The simple fact is that if the cable is
overloaded then it will melt and cause a fire, it will then also

Bit of a red herring there. We are talking about a DVR with its own
internal overload protection. So overload is non issue.

The only thing we need demonstrate is that the plug fuse will clear a
fault at the far end of the lead.

(and that is just a matter of establishing the Prospective Fault
Current, and the applying the adiabatic equation[1] to establish if the
flex has enough cross section to withstand the fault - we don't even
care if it ends up with a conductor temperature north of 150 deg C in
the process, so long as the thing does not vaporise or burst into flames)

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

short out the supply causing further risk. To illustrate lets
consider the service fuse in your electricity supply, without it any
short or overload would probably take out at least part of your
street. It's easy to forget that the fuse is there to protect against
overload because in most cases it's blown due to a direct short, but
if you are running a 3KW heater on a 5A lighting circuit with a 13A
fuse, that wire is going to melt sooner or later,

More twaddle really... Even with lighting circuits wired in 1mm^2 T&E
the current handling capacity of the cable will take a 3kW load
indefinitely in the majority of cases (unless the cable is buried in
insulation).

but even assuming
it doesn't, over time the excess heat will make the plastic brittle
and one day it will crack, perhaps when you pick up the cable!

again, probably incorrect.

The current carrying capacity of a cable is dictated by its maximum long
duration conductor temperature. For PVC insulated cables that is
typically 70 deg C. So long as the cable can reach thermal equilibrium
at or below that, then you can expect a long service life from it.

A 13A
fuse will certainly protect a direct short an a 3A cable as it won't
really have time to melt before the fuse blows,

and that is really the end of the discussion - its purpose in life has
been achieved ;-)


but if you want a
demonstration of what can happen try dropping a some 13A stranded
wire across a 12V car battery, make sure you aren't holding it and
there is nothing combustable around though as the whole length will
instantly burn all it's length before it vapourises- It's quite
spectacular, yo might want to wear suitable eye protection as it
could be quite bright.

Not sure how the suggestion that one sticks a 0.5mm^2 CSA flex across a
source capable of supplying several hundred amps for an extended period
demonstrates anything other than how do dangerous stuff and abuse a
battery.

ISTM the poster in question (and I have a feeling this ancient thread
has been discussed here before) does not really have a clear
understanding of the difference types of over current situation that one
may need to protect against.

Overload protection (i.e. stopping something drawing more than its
design current for a prolonged period) is different from clearing a
fault where the only limit on current draw is the resistance of the
wires in question (i.e. a short between live conductors, or between an
line and earth conductor).

A fuse may do either or both in different circumstances.

(plug fuses are not usually called on to provide overload protection,
apart from the situation where they are protecting a spur from a high
capacity circuit. (you could also include multiway extension leads in
that category))


Having said that, there is a slight advantage to using lower rated plug
fuses when running appliances from extension leads or in other
circumstances when cascaded from another BS1362 13A fuse, since they may
discriminate better in the event of a fault.

i.e. put the metal leg of your ladder through your drill's battery
charger flex, and a 3A fuse in its plug may blow without taking out the
13A fuse in the multiway extension lead feeding it.



--
Cheers,

John.

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

On 19/11/2016 02:44, wrote:


It's all quite simple. 3A fuses aren't required for new goods that
conform to the law, if extension leads aren't used. IOW in most cases
3A fuses are unnecessary. Now add the real life facts of old appliances,
nonconforming goods, extension leads and daisy chained extension leads
and it's easy to see why 3A fuses are still a smart idea.


NT


Just a thought but do you know if they have ever been "required". I ask
because, when I were a lad (late 60s early 70s) our council house was
rewired from 15A Round pin to 13A square pin. The contractors who did
the rewiring put new plugs on all of the appliances that were about and
in use and every one of these plugs had a 13A fuse in it.

As a 14 year old who was just starting to get into engineering I thought
this was wrong and changed some of the fuses appropriately. However I
thought the contractors might have been doing a dodgy job and I wrote
off to someone (Cant honestly remember who but BSI comes to mind - their
kite-mark was everywhere at the time).

I definitely got a reply, the gist of which was "Any fuse is better than
none and yes there is nothing really wrong with putting a 13A fuse in a
table lamp"

I have been pretty relaxed about fuse ratings ever since.

--
Chris B (News)

On 18/11/16 22:49, wrote:
On Wednesday, November 7, 2012 at 6:40:34 PM UTC, David Robinson
wrote:
Not my question, or belief, but found here...

http://forums.digitalspy.co.uk/showthread.php?t=1755197


Is there a counter-argument?

Thanks, David.

To "the fuse is there to protect the cable" ? Hmmm, that's rather to
vague, and technically incorrect. I think you need to ask what are we
protecting really, and I beg to differ that the fuse is there to
protect the cable, here are some reasons why:

Really what we are protecting is ourselves and other property from
electrocution and fire, The simple fact is that if the cable is
overloaded then it will melt and cause a fire, it will then also
short out the supply causing further risk. To illustrate lets
consider the service fuse in your electricity supply, without it any
short or overload would probably take out at least part of your
street. It's easy to forget that the fuse is there to protect against
overload because in most cases it's blown due to a direct short, but
if you are running a 3KW heater on a 5A lighting circuit with a 13A
fuse, that wire is going to melt sooner or later, but even assuming
it doesn't, over time the excess heat will make the plastic brittle
and one day it will crack, perhaps when you pick up the cable! A 13A
fuse will certainly protect a direct short an a 3A cable as it won't
really have time to melt before the fuse blows, but if you want a
demonstration of what can happen try dropping a some 13A stranded
wire across a 12V car battery, make sure you aren't holding it and
there is nothing combustable around though as the whole length will
instantly burn all it's length before it vapourises- It's quite
spectacular, yo might want to wear suitable eye protection as it
could be quite bright.




Now try putting your 13A rated bare wire in series with a 13A fuse
across a car battery. I guarantee that the wire will be fine. Google
"Let through energy" for more detail.

The fuse is designed to heat up and melt before the cable heats up to
beyond its operating temperature (70C for PVC insulated).

Yes, a 13A fuse will not help a 3A cable, but you should have had a 3A
fuse there in the first place.

As for your 3kW heater on a 5A lighting circuit - yes, the breaker at
the source WILL protect the cable and will trip before the cable gets to
70C for an otherwise correctly designed and installed circuit.

Blimey 2012, almost up to date.

On an allied subject, Remember some time back an incident where a person
died due to a fuse not blowing when a mains cable was taken up by an old
style beater hover, mostly made of metal. The cord was not the one on the
hoover but one on a table light, which only had a 13 amp fuse not a lower
one so it never blew.
However I'd not suggest taking up live cables in any case to be honest!
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
wrote in message
...
On Wednesday, November 7, 2012 at 6:40:34 PM UTC, David Robinson wrote:
Not my question, or belief, but found here...

http://forums.digitalspy.co.uk/showthread.php?t=1755197


Is there a counter-argument?

Thanks,
David.

To "the fuse is there to protect the cable" ? Hmmm, that's rather to vague,
and technically incorrect. I think you need to ask what are we protecting
really, and I beg to differ that the fuse is there to protect the cable,
here are some reasons why:

Really what we are protecting is ourselves and other property from
electrocution and fire, The simple fact is that if the cable is overloaded
then it will melt and cause a fire, it will then also short out the supply
causing further risk. To illustrate lets consider the service fuse in your
electricity supply, without it any short or overload would probably take out
at least part of your street.
It's easy to forget that the fuse is there to protect against overload
because in most cases it's blown due to a direct short, but if you are
running a 3KW heater on a 5A lighting circuit with a 13A fuse, that wire is
going to melt sooner or later, but even assuming it doesn't, over time the
excess heat will make the plastic brittle and one day it will crack, perhaps
when you pick up the cable! A 13A fuse will certainly protect a direct short
an a 3A cable as it won't really have time to melt before the fuse blows,
but if you want a demonstration of what can happen try dropping a some 13A
stranded wire across a 12V car battery, make sure you aren't holding it and
there is nothing combustable around though as the whole length will
instantly burn all it's length before it vapourises- It's quite spectacular,
yo might want to wear suitable eye protection as it could be quite bright.

On Saturday, 19 November 2016 08:37:48 UTC, Chris B wrote:
On 19/11/2016 02:44, tabbypurr wrote:


It's all quite simple. 3A fuses aren't required for new goods that
conform to the law, if extension leads aren't used. IOW in most cases
3A fuses are unnecessary. Now add the real life facts of old appliances,
nonconforming goods, extension leads and daisy chained extension leads
and it's easy to see why 3A fuses are still a smart idea.


Just a thought but do you know if they have ever been "required". I ask
because, when I were a lad (late 60s early 70s) our council house was
rewired from 15A Round pin to 13A square pin. The contractors who did
the rewiring put new plugs on all of the appliances that were about and
in use and every one of these plugs had a 13A fuse in it.

As a 14 year old who was just starting to get into engineering I thought
this was wrong and changed some of the fuses appropriately. However I
thought the contractors might have been doing a dodgy job and I wrote
off to someone (Cant honestly remember who but BSI comes to mind - their
kite-mark was everywhere at the time).

I definitely got a reply, the gist of which was "Any fuse is better than
none and yes there is nothing really wrong with putting a 13A fuse in a
table lamp"

I have been pretty relaxed about fuse ratings ever since.

It sounds like you were wrongly advised. At that time a lot of table lamps & some other goods used what is now regarded as speaker flex for a mains lead. This stuff is not protected by a 13A fuse, it requires a 3A to be safer.. Also other appliances in use at that time could not be counted on to have inbuilt overload protection.

OTOH the safety standards of the day were a lot laxer. There was plenty of class 0 stuff in use, wires stuffed under plugs, heating run on 1930s lighting circuits, taped twisted flex joints and so on.


NT

Brian Gaff wrote:

Blimey 2012, almost up to date.

On an allied subject, Remember some time back an incident where a person
died due to a fuse not blowing when a mains cable was taken up by an old
style beater hover, mostly made of metal. The cord was not the one on the
hoover but one on a table light, which only had a 13 amp fuse not a lower
one so it never blew.
However I'd not suggest taking up live cables in any case to be honest!
Brian

I really don't think the size of the fuse on the table lamp is the issue
here. It is hoover not being effectively earthed that is the immediate
problem. If it had been earthed it would not have reached a dangerous
voltage and either the 13A fuse or the flex to the table lamp would have
melted and broken the connection.


--

Roger Hayter

I will stick to fusing with the lowest capacity fuse to suit the current of
the appliance. I want the fuse to blow as soon as possible if there is a
fault.