Are 3A plug fuses really necessary? Why not always 13A?

[David Robinson]

Not my question, or belief, but found here...

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


Is there a counter-argument?

Thanks,
David.

[John Williamson]

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?
>

It depends on the cross sectional area of the cable cores. As is
correctly pointed out in the thread, the fuse is to protect against
cable faults, not internal faults in the box. If the cores are too
small, a 13 A fuse may not blow or carry enough current to rapidly trip
the MCB, leading to a cable that at the best is going to melt the
insulation, and at worst may start a fire.


--
Tciao for Now!

John.

[GB]

On 07/11/2012 18:50, John Williamson wrote:

> It depends on the cross sectional area of the cable cores. As is
> correctly pointed out in the thread, the fuse is to protect against
> cable faults, not internal faults in the box. If the cores are too
> small, a 13 A fuse may not blow or carry enough current to rapidly trip
> the MCB, leading to a cable that at the best is going to melt the
> insulation, and at worst may start a fire.

Just anecdotally, I had a decorator in my house using a steam stripper.
He asked to borrow an extension lead, and I conscientiously checked the
extension lead was man enough for the job, then left him to it. Half an
hour later, the power went off.

Investigating, I found that he hadn't bothered to unreel more of the
extension cable than he needed to reach the job - despite clear
instructions on the reel to that effect. The entire lot inside the reel
had melted, and the power went off when the cores touched. This was a
man who had been doing this sort of work for over 10 years, mind.

[Hugh - in either England or Spain]

Have to admit I have done the same. Stripper well within reels
capability but it cut out after a while. My reel has an overheat cut-out
fortunately. Lesson learned for all types of wiring.

If I take anything bought in Spain back to the UK I will have to change
the plug or use it through a correctly fused adaptor. Using them unfused
on a 30A ring main could be a recipe for disaster.

Worries me sightly that lamps and other itmes out here with thin flex
plug into fairly highly rated power sockets.

[Graham.]

Here's a counter argument I made a couple of years ago in response to
those that say it's only there to protect the cable.

[It] May not be mandated for appliance protection, but isn't it true
to say that choosing
a plug fuse value sensibly having regard for the maximum current
demand of
the appliance rather than than just the capability of the cable has
always been good practice?

The appliance manufactures seem to think so.

Take the case of three items I regularly install, all with supplied
0.75mm2 IDE cables

A Dell PC with a 5A fuse in the plug
A Cisco router with a 10A fuse
A Brother laser printer with 13A fuse.

Of course this might now create issues with interchangability.
I would be interested to see your comments about the above.


--
Graham.
%Profound_observation%

[meow...@care2.com]

All modern appliances and leads are required to be safe with a 13A fuse. However the reality is that fires do happen, and there are at least some faults where a 3A would blow before a 13A, so maybe preventing a small percentage of fires.

Old appliances are another matter, and many are not properly protected by a 13A fuse.

So its better to keep using 3A where suitable.


NT

[ARW]

I am sure that some boiler installation manuals state the use of a 3A fuse -
and there is no legal reason why a boiler cannot be powered using a plug and
unswitched socket......

--
Adam

[Bill Wright]

13A fuses can go with a right bang, frightening old ladies. 3A fuses are
nicer.

Bill

[polygonum]

Please can you provide a reference to when that changed? And, ideally,
what the requirements actually are - in an accessible form.

--
Rod

[Dave Liquorice]

On Wed, 07 Nov 2012 20:47:53 +0000, polygonum wrote:

>> All modern appliances and leads are required to be safe with a 13A
>> fuse. However the reality is that fires do happen, and there are at
>> least some faults where a 3A would blow before a 13A, so maybe
>> preventing a small percentage of fires.
>

> Please can you provide a reference to when that changed? And, ideally,
> what the requirements actually are - in an accessible form.

That would be interesting.

The big bad assumption made in the digital spy thread was to assume only
short circuit faults and that massive currents will flow. In that
particular case there is little difference between a 3A or 13A fuse.

However if the short circuit current is only high, maybe limited by weak
spring tension in the fuse holder, corosion of the holdler/fuse cap,
dodgy wire termination some where, and say only 20A is flowing. Thene
there is a significant difference between a 3A and 13A fuse.

--
Cheers
Dave.

[Dave Liquorice]

On Wed, 07 Nov 2012 19:19:33 +0000, GB wrote:

> Investigating, I found that he hadn't bothered to unreel more of the
> extension cable than he needed to reach the job - despite clear
> instructions on the reel to that effect. The entire lot inside the reel
> had melted, and the power went off when the cores touched. This was a
> man who had been doing this sort of work for over 10 years, mind.

And was his comment "That's odd. The last time I used a cable reel like
that one, the same thing happened".

I hope he paid for a replacement.

--
Cheers
Dave.

[The Natural Philosopher]

Or more to the point, under overcurrent, which would you rather have go?
a thin piece of flex with plastic insulation lying over a newspaper, or
a fuse in a plug.


--
Ineptocracy

(in-ep-toc’-ra-cy) – a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

[Peter Crosland]

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.


--
Regards Peter Crosland

[John Rumm]

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?

Counter to what?

Frank1 is obviously missing a clue.

grahamthompson and Nigel Goodwin seem to have explained more than
adequately.

Its easy enough to check. From the BS7671:2008 table 41.3[1], the
maximum earth loop impedance for a circuit protected by a B32 MCB is
1.44 ohms. That is what gives a fault current on the longest path of the
circuit of around 160A - or enough to open a B32 MCB on the "instant"
part of its trip response.

So we could take that as an example of the minimum fault current the
flex will need to withstand when someone shorts it.

Lets say the appliance has a flex with 0.5mm^2 CSA conductors. For a
short flex (i.e. typically 1.8m) you can ignore the additional
resistance of the flex, so can just assume the prospective fault current
of 160A. Now that should open a 13A fuse in less than 0.1 secs (probably
significantly less). So all you need to know is, will the flex will
carry that fault current for long enough to allow the fuse to do its
stuff without either vaporising or bursting into flames.

So we can work out the minimum size (s) of conductor required for that
with the adiabatic equation[2] and the PVC cable type k value of 115.

s = sqrt( 160^2 x 0.1 ) / 115

s = 0.44mm^2

Which is less that the actual flex CSA of 0.5mm^2, so in this particular
example the flex would actually be adequately protected by the 32A MCB
at the origin of the circuit (although the fuse will probably open
before the MCB gets a chance to operate)

If you try that sum on a shorter circuit - or one with a lower Ze, then
you may get an ELI of say 0.5 ohms at the end of the flex. That gives a
fault current of 460A which would need a conductor size of aver 1mm^2 to
be protected by the main MCB, so here the fuse would be essential.

(if the circuit were protected by a BS3036 rewireable fuse, or the
circuit a tad out of spec, the flex longer or thinner etc then the fuse
in the plug would be essential).



[1]
http://wiki.diyfaq.org.uk/index.php?title=Calculating_A_Cable_Size#Checking_the_Maximum_Earth_Loop_Impedance

[2]
http://wiki.diyfaq.org.uk/index.php?title=Calculating_A_Cable_Size#Adiabatic_Check

--
Cheers,

John.

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

[John Rumm]

On 07/11/2012 20:20, Graham. wrote:
> On Wed, 7 Nov 2012 10:40:34 -0800 (PST), David Robinson
> <davidr...@postmaster.co.uk> 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.
>
>
> Here's a counter argument I made a couple of years ago in response to
> those that say it's only there to protect the cable.
>
> [It] May not be mandated for appliance protection, but isn't it true
> to say that choosing
> a plug fuse value sensibly having regard for the maximum current
> demand of
> the appliance rather than than just the capability of the cable has
> always been good practice?

Indeed - but its not a counter argument. The logic Humax (or whoever)
are applying is that the 13A fuse is adequate to protect the flex. That
is demonstrably true.

However what you say is also true, and in no way conflicts with that.

More closely matching the actual size required will mean that when
things do go pear shaped, the actual energy let through may be a little
lower. Less spark, less heating stress on the cables etc.

> The appliance manufactures seem to think so.
>
> Take the case of three items I regularly install, all with supplied
> 0.75mm2 IDE cables

Strange place to be using a disk interface cable ;-)

(IEC perhaps?)

> A Dell PC with a 5A fuse in the plug
> A Cisco router with a 10A fuse
> A Brother laser printer with 13A fuse.
>
> Of course this might now create issues with interchangability.
> I would be interested to see your comments about the above.

For stuff running with "normal" IEC leads its does not make any real
difference. The appliance will have an internal fuse if it needs it, and
the cables are quite sturdy (assuming they are not Chinese knock offs!)
The kit will have been designed to run safely on 16A circuits with no
plug fuse (as it will need to in most countries) so the flex will be
specced to suit.

IME leads for IT kit doe get swapped about without any regard for their
rating (most people have not even spotted there are two different specs
of lead and fuse). So 3A fusing may be pushing your luck depending on
what it gets connected to.

[John Rumm]

If there is only 20A of fault current, then there is 11.5 ohms of
resistance somewhere! The > 4kW you are dissipating in the fuse holder
might be more of a worry than whatever is going on with the flex ;-)

[John Rumm]

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

http://s833.beta.photobucket.com/user/Elmer_BeFuddled/media/CounterfeitFuse.mp4.html

or

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

[Graham.]

Damn. that will teach me to proof read my own regurgitated words. In
the original thread you quipped:
"You can see why SATA became popular if the IDE leads were that size"

--
Graham.
%Profound_observation%

[meow...@care2.com]

On Wednesday, November 7, 2012 8:47:55 PM UTC, polygonum wrote:
> On 07/11/2012 20:33, meow...@care2.com wrote:
> > On Wednesday, November 7, 2012 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.

> > All modern appliances and leads are required to be safe with a 13A
> > fuse. However the reality is that fires do happen, and there are at
> > least some faults where a 3A would blow before a 13A, so maybe
> > preventing a small percentage of fires.
> >
> > Old appliances are another matter, and many are not properly
> > protected by a 13A fuse.
> >
> > So its better to keep using 3A where suitable.

> Please can you provide a reference to when that changed? And, ideally,
> what the requirements actually are - in an accessible form.

Unfortuately no, I've not kept any notes of those points. One thing it has changed is the minimum permissible conductor cross section in appliance leads, if you look at appliances from the 50s and 60s, some shavers & clocks etc have very thin conductors. Now all new flexes need to be able to survive the i squared t of a 13A fuse blow.


NT

[Frank Erskine]

On Wed, 07 Nov 2012 22:26:06 +0000, Peter Crosland <g6...@yahoo.co.uk>
wrote:

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

[polygonum]

Heigh-ho. Anyone else know?

--
Rod

[Graham.]

On Wed, 07 Nov 2012 22:44:35 +0000, John Rumm
<see.my.s...@nowhere.null> wrote:

>On 07/11/2012 20:41, Bill Wright wrote:
>> 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.
>> 13A fuses can go with a right bang, frightening old ladies. 3A fuses are
>> nicer.
>
>You want to see the bang with the counterfeit ones arriving with your
>latest mains lead from China via ebay:
>
>http://s833.beta.photobucket.com/user/Elmer_BeFuddled/media/CounterfeitFuse.mp4.html
>
>or
>
>http://www.bs1363.org.uk/counterfeit_fuse.mpeg

I assure you there was no dummy fuse in the adapter I got with a
handheld transceiver from China recently.
http://www.flickr.com/photos/g3zvt/8165352944/in/photostream/lightbox/

The strange thing was that the charger supplied had a Euro plug, so
didn't fit this adapter anyway.

The black sleeving on the pins appears to be thin heatshrink that I
could easily pick odd with a fingernail.

I wonder what internal protection a wall-wart with a Euro or Stucco
pins has to have compared to one with our 13A pins?
Without an x-ray machine, you've only got their word that they are
safe, and they are not only at the mercy of a 32A MCB.

--
Graham.
%Profound_observation%

[Graham.]

If I just reach in this drawer...
http://www.flickr.com/photos/g3zvt/8165426270/in/photostream/lightbox/

--
Graham.
%Profound_observation%

[Martin Crossley]

It was around the time the voltages were harmonised at 230V, flexes were
marked <HAR> and CE marking came in.
1995?

[John Rumm]

Lol, which to be fair I had completely forgotten about until your
comment prompted me to search for it (well it was 18 months ago!)

Still nice to know that even of my memory is going I am still consistent
(or predictable!)

[charles]

In article <79sl981rkkm75ood9...@4ax.com>,

clock plugs use a smaller fuse. They are 19mm long as opposed to 1" for
BS1362.

CPC stock 1A,2A,3A,5A,7A,10A & 13A in BS1362 size

--
From KT24

Using a RISC OS computer running v5.18

[harry]

That's about the size of it.

Years ago a "Euro-plug" was designed. It had no fuse and was a
throwback to the fifteen amp plugs we had nicely got rid of. I think
it was sixteen amp.
Fortunately it was abandoned. MK actually started making them.

I think the 13a plug is the only one in the world with a fuse.
There was another where the fuse was a screw-in pin on the plug.
Haven't seen one for years.

[A.Lee]

Dave Liquorice <allsortsn...@howhill.com> wrote:

> However if the short circuit current is only high, maybe limited by weak
> spring tension in the fuse holder, corosion of the holdler/fuse cap,
> dodgy wire termination some where, and say only 20A is flowing. Thene
> there is a significant difference between a 3A and 13A fuse.

Exactly.
Like in the house I was working at this week. the best earth fault loop
reading I could get on the 30A fused socket outlets was 5.6 ohms.The
worst, 9ohms.
At the 'best' socket, with 5.6 ohms, at the measured voltage of 247V, it
would be passing 44 amps, which just wouldnt break the fusebox fuse.

At the worst socket, it would be passing 27 Amps, which may break a 13A
fuse, but I doubt it would do it in 0.4 of a second, more like a second,
which is enough to kill.
A 3A fuse would break it immediately (well, ok, in less than half a
second).
The fuse in the fusebox will be happlily buzzing away, passing the
current for half an hour before it broke. The figures were likely to be
worse in the evening, as other people came home, and the voltage may
drop a little, allowing more current through.

Ok, thats an extreme example, but a true one, so the final fuse rating
can have safety implications, hence best to put the lowest rating
possible in.

Alan.

--
To reply by e-mail, change the ' + ' to 'plus'.

[harry]

Not all faults are dead shorts. Transformer overheat/burnout for
example.
Not all equipment has internal fuses.
3Kw/13a of sustained energy in an electronic device/small electric
motor could start a nice little fire.

[harry]

On Nov 7, 11:56 pm, Frank Erskine <frank.ersk...@btinternet.com>
wrote:

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.
There have been all sorts of odd sizes over the years.

[Mike Barnes]

meow...@care2.com:

I remember those thin leads. My '60s soldering iron had a lead about
half the diameter of (today's!) CAT5 patch cables. My assumption up
until now has been that globalisation has resulted in all leads being
designed for the unfused plugs used in most of the world outside the UK.

--
Mike Barnes

[meow...@care2.com]

Optional mains plug fuses were in use a century ago in the UK, but they were open wire links in plugs that were often wooden. They were banned in 1913 as a fire risk.


NT

[charles]

In article
<96c1a4ee-d434-4db3...@c17g2000yqe.googlegroups.com>,

harry <harry...@btinternet.com> wrote:
> On Nov 7, 10:26 pm, Peter Crosland <g6...@yahoo.co.uk> 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.

> That's about the size of it.

> Years ago a "Euro-plug" was designed. It had no fuse and was a
> throwback to the fifteen amp plugs we had nicely got rid of. I think
> it was sixteen amp.
> Fortunately it was abandoned. MK actually started making them.

do you mean the CEEform plug? MK Commando, etc. Very much in use.

> I think the 13a plug is the only one in the world with a fuse.

some of our old 5A round pin plugs had fuses. Perhasp they still do in
India.

> There was another where the fuse was a screw-in pin on the plug.
> Haven't seen one for years.

those were made by D&S.

[John Rumm]

> Not all faults are dead shorts. Transformer overheat/burnout for
> example.

For the purposes of this discussion they are (its in the definition of
"fault current")

Transformers are unlikely to be able to present any sustained load above
their design maximum for long - the wire size on their primary winding
will typically be *significantly* thinner than that of the supply flex.

> Not all equipment has internal fuses.

If it needs overload protection then it is required to have its own
protection. Remember in most markets, protection via a plug fuse is not
an option.

> 3Kw/13a of sustained energy in an electronic device/small electric
> motor could start a nice little fire.

Which would be an overload and not a fault. If there is a plausible
overload scenario, then the device in question must include its own
protection.

[Man at B&Q]

Is it Panto time yet? Oh yes they are.

And all short circuits are faults.

Anything else is an overload.

MBQ

[dochol...@gmail.com]

On Wednesday, November 7, 2012 11:56:12 PM UTC, Frank Erskine wrote:

> 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?)?

1,2,3,5,7,10 and 13A fuses are all still available. I remember seeing 1A fuses in clock plugs - though some clock plugs used fuses with a different mechanical size just to be awkward...

[The Natural Philosopher]

On 08/11/12 10:49, Man at B&Q wrote:
all short circuits are faults.
>
> Anything else is an overload.
>

What a peculiar version of the english language you speak...

Lets say we have an SMPS, and due to a fault in the main 400V reservoir
on the mains side, it starts leaking several amps ...

You are saying that's not a fault?

[meow...@care2.com]

On Thursday, November 8, 2012 10:46:10 AM UTC, John Rumm wrote:
> On 08/11/2012 07:52, harry wrote:
> > On Nov 7, 10:35 pm, John Rumm <see.my.signat...@nowhere.null> wrote:
> >> On 07/11/2012 20:20, Graham. wrote:
> >>> On Wed, 7 Nov 2012 10:40:34 -0800 (PST), David Robinson
> >>> <davidrobin...@postmaster.co.uk> wrote:



> > Not all faults are dead shorts. Transformer overheat/burnout for
> > example.

> For the purposes of this discussion they are (its in the definition of
> "fault current")

Welcome to the strange world of Aurthur Brown. The wiring regs use 'fault current' to specifically mean a dead short, but obviously in the real world appliance faults occur that produce current (fault current by definition) that covers the full range from a smallish increase than only overheats a motor to a dead short. Introducing a narrow perspective definition that applies specifically to wiring and using it outside of where it makes good sense is not productive, and insisting it must mean that elsewhere is illogical. In the world of electronics (which many appliances are) fault current does not usually mean a dead short across the mains.

> Transformers are unlikely to be able to present any sustained load above
> their design maximum for long - the wire size on their primary winding
> will typically be *significantly* thinner than that of the supply flex.

> > Not all equipment has internal fuses.

> If it needs overload protection then it is required to have its own
> protection.

In practice not all has, particularly old appliances

> Remember in most markets, protection via a plug fuse is not
> an option.

Old UK appliances were typically designed for only the UK market

> > 3Kw/13a of sustained energy in an electronic device/small electric
> > motor could start a nice little fire.

> Which would be an overload and not a fault. If there is a plausible
> overload scenario, then the device in question must include its own
> protection.

But in practice a fair few don't. There are still significant numbers of old electrical goods in use spanning the range from pre-95 to 1920s. And not all new goods meet the standards legally required of them.


NT

[Man at B&Q]

On Nov 8, 12:33 pm, The Natural Philosopher <t...@invalid.invalid>
wrote:

> On 08/11/12 10:49, Man at B&Q wrote:
> all short circuits are faults.
>
> > Anything else is an overload.
>
> What a peculiar version of the english language you speak...
>
> Lets say we have an SMPS, and due to a fault in the main 400V reservoir
> on the mains side, it starts leaking several amps ...
>
> You are saying that's not a fault?

Well, it is faulty, but in the jargon, that is not a fault current.

MBQ

[whisky-dave]

On Wednesday, November 7, 2012 8:20:19 PM UTC, Graham. wrote:
> On Wed, 7 Nov 2012 10:40:34 -0800 (PST), David Robinson
>

> <davidr...@postmaster.co.uk> 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.
>
>
>
>
>
> Here's a counter argument I made a couple of years ago in response to
>
> those that say it's only there to protect the cable.
>
>
>
> [It] May not be mandated for appliance protection, but isn't it true
>
> to say that choosing
>
> a plug fuse value sensibly having regard for the maximum current
>
> demand of
>
> the appliance rather than than just the capability of the cable has
>
> always been good practice?
>
>
>

> The appliance manufactures seem to think so.
>
>
>
> Take the case of three items I regularly install, all with supplied
>
> 0.75mm2 IDE cables
>
>
>

> A Dell PC with a 5A fuse in the plug

That seems OK as few computers would exceed 1kw
but if that lead was used as a kettle lead.....

>
> A Cisco router with a 10A fuse

No idea perhaps they had a lot of 10Amp fuses spare I have, I think they are black, 13Amp brown and 3A red.

>
> A Brother laser printer with 13A fuse.

In the days ofm teh first laser printers they took quite a heaft startup current, in fact you shouldn;t put laswer printers on sureg protection blaocks either. Not sur eif it's still true as I can't believe the modern USB laserpriners would need a high startup cutrrent....

>
>
>
> Of course this might now create issues with interchangability.
>
> I would be interested to see your comments about the above.

I broguht about 100 "Y" leads that have two IEC sockets on the end and they have 13amp fuses. There's a health and safety notice that says were not allowed to use them as you can't connect two pieces of equipment to one plug.


>
>
>
>
>
> --
>
> Graham.
>
> %Profound_observation%

[Mike Tomlinson]

In article <Zr2dncYhfNDyeQfN...@brightview.co.uk>, John
Rumm <see.my.s...@nowhere.null> writes

>http://s833.beta.photobucket.com/user/Elmer_BeFuddled/media/CounterfeitFuse.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.

--
(\_/)
(='.'=)
(")_(")

[David WE Roberts]

"David Robinson" <davidr...@postmaster.co.uk> wrote in message
news:94667b91-ef5d-4c75...@k20g2000vbj.googlegroups.com...

> Not my question, or belief, but found here...
>
> http://forums.digitalspy.co.uk/showthread.php?t=1755197
>
>
> Is there a counter-argument?

Just to note that I've just replaced the 5A fuse in an extension lead for
the second time in a week.
Rated 4A coiled and 5A uncoiled.
We use it for lights but passing builders tend to plug anything into
anything.
So yes, the fuse does protect the cable :-)

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)

[Mike Tomlinson]

In article <Vvadne0ZO_qFfQfN...@brightview.co.uk>, John
Rumm <see.my.s...@nowhere.null> writes

>(if the circuit were protected by a BS3036 rewireable fuse, or the
>circuit a tad out of spec, the flex longer or thinner etc then the fuse
>in the plug would be essential).

And this is part of the reason why appliance flexes are so short
nowadays: not only is the manufacturer saving a few pennies but they're
ensuring the flex is short enough with low enough resistance for a fault
current to blow the 13A fuse in the plug.

--
(\_/)

[Mike Tomlinson]

In article <79sl981rkkm75ood9...@4ax.com>, Frank Erskine

<frank....@btinternet.com> writes

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

Pretty sure 5A is still commonly available.

The RS catalogue does BS1362 fuses in 1A, 2A, 3A, 5A, 7A, 10A and 13A.

>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?)?

In clock plugs, yes, 1A fuses are (were) common. Clocks used to be
connected with what was essentially bell wire.

For myself, I fit 3, 5 or 13A depending on what is appropriate for the
load. 3A for things like lamps, 5A for stuff like PCs and TVs, 13A for
washing machine, fridge/freezer, dishwasher, etc.

I fitted a 1A fuse in the plug for something recently, buggered if I can
remember what it was though. Something like christmas tree lights IIRC.

[John Rumm]

On 08/11/2012 12:51, meow...@care2.com wrote:
> On Thursday, November 8, 2012 10:46:10 AM UTC, John Rumm wrote:
>> On 08/11/2012 07:52, harry wrote:
>>> On Nov 7, 10:35 pm, John Rumm <see.my.signat...@nowhere.null>
>>> wrote:
>>>> On 07/11/2012 20:20, Graham. wrote:
>>>>> On Wed, 7 Nov 2012 10:40:34 -0800 (PST), David Robinson
>>>>> <davidrobin...@postmaster.co.uk> wrote:
>
>
>
>>> Not all faults are dead shorts. Transformer overheat/burnout
>>> for example.
>
>> For the purposes of this discussion they are (its in the definition
>> of "fault current")
>
> Welcome to the strange world of Aurthur Brown. The wiring regs use
> 'fault current' to specifically mean a dead short, but obviously in
> the real world appliance faults occur that produce current (fault
> current by definition) that covers the full range from a smallish
> increase than only overheats a motor to a dead short.

Indeed. However the wiring regs separate these out into overload and
fault since they need to be treated separately.

> Introducing a
> narrow perspective definition that applies specifically to wiring and
> using it outside of where it makes good sense is not productive, and

Except in this case we are not using it outside. The link the OP
referred to was a very specific question about whether a small
electronic device can be adequately "protected" by a 13A fuse. The
answer to which is yes. The protection that the fuse is there to offer
is to limit the effects of fault current - i.e. stopping the mains lead
bursting into flames, vaporising and spewing hot metal and plastic about
the place etc when someone sticks a metal chair leg through it. Once you
can demonstrate that you have achieved that level of protection, then
your job (and that of the fuse in the plug) is done.

This is a completely separate issue from minimising damage to the device
itself because some internal motor got latched on when it should not
have, and its now sucking more power than it ought. Yes that is a
"fault" in the device, and that may result in overcurrent (wiring regs
use of the term). If its a problem, then the designer can do something
about it.

> insisting it must mean that elsewhere is illogical. In the world of
> electronics (which many appliances are) fault current does not
> usually mean a dead short across the mains.

True, but not relevant to the point under discussion.

If you want to protect electronics you are designing now from damage
resulting from overload, then you need a fuse (or thermal cutout etc).
However you can't rely on the one in the plug, since outside the UK it
won't be there.

>> Transformers are unlikely to be able to present any sustained load
>> above their design maximum for long - the wire size on their
>> primary winding will typically be *significantly* thinner than that
>> of the supply flex.
>
>>> Not all equipment has internal fuses.
>
>> If it needs overload protection then it is required to have its
>> own protection.
>
> In practice not all has, particularly old appliances
>
>> Remember in most markets, protection via a plug fuse is not an
>> option.
>
> Old UK appliances were typically designed for only the UK market

Indeed. And for those, a lower rating fuse may be required in the plug.

Don't confuse the situation as it applies to fault current protection
for the flex on a new device one is putting onto the market in the EU
now, with old kit built to different requirements and standards.

Also don't assume that just because a 13A fuse will meet the fundamental
requirement for fault protection on new kit that there is no benefit you
using a lower value fuse in some cases. There might be.

>>> 3Kw/13a of sustained energy in an electronic device/small
>>> electric motor could start a nice little fire.
>
>> Which would be an overload and not a fault. If there is a
>> plausible overload scenario, then the device in question must
>> include its own protection.
>
> But in practice a fair few don't. There are still significant numbers
> of old electrical goods in use spanning the range from pre-95 to
> 1920s. And not all new goods meet the standards legally required of
> them.

As I said, in these cases if the maker said the appliance must be
protected by a 3A fuse then so be it. If they designed it to rely on a
3A fuse in a plug, that is fine, use one and not a 13A. They would not
be able to do it now (for a product to be marketed internationally) but
it does not mean it did not happen in the past.

Fault current protection is a minimum requirement - something that must
be taken into account and protection put in place for. None of that
precludes doing more than the minimum.

[John Rumm]

On 08/11/2012 13:48, whisky-dave wrote:

>> A Dell PC with a 5A fuse in the plug
>
> That seems OK as few computers would exceed 1kw but if that lead was
> used as a kettle lead.....

The irony that has been highlighted before, the one thing that what many
people refer to as a "kettle lead" won't fit, is a kettle!

(i.e. an IEC cold condition connector won't go into an IEC hot condition
appliance).

>> A Cisco router with a 10A fuse
>
> No idea perhaps they had a lot of 10Amp fuses spare I have, I think
> they are black, 13Amp brown and 3A red.

IIRC, all fuses that are not 3 or 13A are required to be black now...

>> A Brother laser printer with 13A fuse.
>
> In the days ofm teh first laser printers they took quite a heaft
> startup current, in fact you shouldn;t put laswer printers on sureg
> protection blaocks either.

They are fine on just a normal surge protected supply - but they are not
usually put onto UPS supplies. (many UPSs will have a dedicated surge
suppressed outlet that is not maintained during mains interruption for
the purposes of powering stuff like laser printers)

> Not sur eif it's still true as I can't
> believe the modern USB laserpriners would need a high startup
> cutrrent....

Modern ones can be worse rather than better. Old ones tended to heat the
fuser and keep it hot. They might have a long startup time, but then
once hot, were ready to go. More energy efficient ones will use "instant
on" fusees, but these may require higher short term currents to minimise
the delay in printing the first page.

[John Rumm]

Na, just air...

Shows you want a fault current (wiring regs meaning) can do!

[John Rumm]

or more likely needing to be short enough to open a 16A MCB (that and
being cheapskates!)

(short leads on power tools get on my tits!)

[whisky-dave]

On Thursday, November 8, 2012 2:59:37 PM UTC, John Rumm wrote:
> On 08/11/2012 13:57, Mike Tomlinson wrote:
>
> > In article <Vvadne0ZO_qFfQfN...@brightview.co.uk>, John
>
> > Rumm <see.my.s...@nowhere.null> writes
>
> >
>
> >> (if the circuit were protected by a BS3036 rewireable fuse, or the
>
> >> circuit a tad out of spec, the flex longer or thinner etc then the fuse
>
> >> in the plug would be essential).
>
> >
>
> > And this is part of the reason why appliance flexes are so short
>
> > nowadays: not only is the manufacturer saving a few pennies but they're
>
> > ensuring the flex is short enough with low enough resistance for a fault
>
> > current to blow the 13A fuse in the plug.
>
>
>
> or more likely needing to be short enough to open a 16A MCB (that and
>
> being cheapskates!)
>
>
>
> (short leads on power tools get on my tits!)

Well that's the problem with long lead they can reach tits ;-)

[polygonum]

On 08/11/2012 00:47, Martin Crossley wrote:
<>
>
> It was around the time the voltages were harmonised at 230V, flexes were
> marked <HAR> and CE marking came in.
> 1995?
>
>
I remember the ads now Har, Har, Harmony... :-)

Never noticed that on a flex - only CE and other markings.

--
Rod

[bert]

In message <7voWMoBy...@jasper.org.uk>, Mike Tomlinson
<mi...@jasper.org.uk> writes

>For myself, I fit 3, 5 or 13A depending on what is appropriate for the
>load. 3A for things like lamps, 5A for stuff like PCs and TVs, 13A for
>washing machine, fridge/freezer, dishwasher, etc.

<Snip>

My approach too. They can argue about the semantics as much as they like
but to me it make sense to have the minimum fuse necessary and also not
to rely on the safety device as an inherent part of the design.
--
bert

[meow...@care2.com]

They're very different. It was common for old appliances to rely entirely for overload protection on the plug fuse, and often to require it to be 5A rather than 15A. It was also common to simply not consider the issue.

> Also don't assume that just because a 13A fuse will meet the fundamental
> requirement for fault protection on new kit that there is no benefit you
> using a lower value fuse in some cases. There might be.

There often is, a 3A fuse ruptures much quicker than 13A in many fault/overload scenarios, and that can prevent fire sometimes.

> >>> 3Kw/13a of sustained energy in an electronic device/small
> >>> electric motor could start a nice little fire.
> >
> >> Which would be an overload and not a fault. If there is a
> >> plausible overload scenario, then the device in question must
> >> include its own protection.
> >
> > But in practice a fair few don't. There are still significant numbers
> > of old electrical goods in use spanning the range from pre-95 to
> > 1920s. And not all new goods meet the standards legally required of
> > them.
> As I said, in these cases if the maker said the appliance must be
> protected by a 3A fuse then so be it. If they designed it to rely on a
> 3A fuse in a plug, that is fine, use one and not a 13A. They would not
> be able to do it now (for a product to be marketed internationally) but
> it does not mean it did not happen in the past.

I think the normal recommendations were 5A, 2A, and sometimes 1A, and later 3A. But tracking any such recommendations is unlikely to work out in many cases, and many manufacturers simply ignored the issue. Some of the safety issues were very basic, a lot didn't even have a cordgrip. I recall one relatively well regarded 1960s product that used a strip of ali foil for earthing, stapled down to connect it.

> Fault current protection is a minimum requirement - something that must
> be taken into account and protection put in place for. None of that
> precludes doing more than the minimum.

Exactly.


NT

[The Other Mike]

On Wed, 07 Nov 2012 22:44:35 +0000, John Rumm <see.my.s...@nowhere.null>
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 ?
--

[Mike Barnes]

Man at B&Q <manat...@hotmail.com>:

So, you're agreed. The jargon = a peculiar version of English.

--
Mike Barnes

[Jules Richardson]

On Thu, 08 Nov 2012 14:55:34 +0000, John Rumm wrote:

> On 08/11/2012 13:48, whisky-dave wrote:
>
>>> A Dell PC with a 5A fuse in the plug
>>
>> That seems OK as few computers would exceed 1kw but if that lead was
>> used as a kettle lead.....

I remember having one computer which needed a 'kettle lead' with a notch
cut out of it (which may indeed be a *real* 'kettle lead' connector, but
I never did check). PSU was rated to 800W IIRC, and it was probably
running at close to that.

[Jules Richardson]

On Wed, 07 Nov 2012 23:43:36 -0800, harry wrote:
> I think the 13a plug is the only one in the world with a fuse.

Fused plugs do exist here in the US, most often seen on Christmas tree
lights (the ones that are made here, rather than the China-built death
traps) - they have a little trapdoor in them for fuse access (US plugs
are tiny in comparison the the UK's chunk-o-rama ones :-) and a pair of
fuses that are around 10mm in length.

cheers

Jules

[Graham.]

On Wed, 7 Nov 2012 23:57:08 -0800 (PST), harry
<harry...@btinternet.com> wrote:

>On Nov 7, 11:56 pm, Frank Erskine <frank.ersk...@btinternet.com>
>wrote:
>> On Wed, 07 Nov 2012 22:26:06 +0000, Peter Crosland <g6...@yahoo.co.uk>

>> 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.
>There have been all sorts of odd sizes over the years.

I have a working mains clock on the desk here, with starter and
tick/silent gismos.
The clock connecter fuse is the same size as the ones on 5A Wylex
plugs.

--
Graham.
%Profound_observation%

[Doctor Drivel]

"David WE Roberts" <nos...@btinternet.com> wrote in message
news:ag1s4u...@mid.individual.net...

>
> "David Robinson" <davidr...@postmaster.co.uk> wrote in message
> news:94667b91-ef5d-4c75...@k20g2000vbj.googlegroups.com...
>> Not my question, or belief, but found here...
>>
>> http://forums.digitalspy.co.uk/showthread.php?t=1755197
>>
>>
>> Is there a counter-argument?
>
>
> Just to note that I've just replaced the 5A fuse in an extension lead for
> the second time in a week.
> Rated 4A coiled and 5A uncoiled.
> We use it for lights but passing builders tend to plug anything into
> anything.
> So yes, the fuse does protect the cable :-)

You are correct, but a little slower - it may go to 4A before the fuse
breaks. If current is say 1A and the fuse 3A, then the current increases for
whatever to 4A the fuse may not break so quick, but will eventually, so
giving protection. 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.

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. They only time the current would be high enough to melt
the flex would be if there is a fault, which would be momentarily and the
fuse would then snap. I "think" that is what is he on about. He says the
13A fuse will break faster on a fault than a 3A. BTW, I recall as a kid my
sister's cheap Italian (looked good though) table lamp switch melting. It
obviously had a "fault" and" a 13A fuse. A 3A fuse would have snapped
stopping the melting, which was a fire hazard. The switch could be classed
as a part of the cable and the appliance the light bulb.

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

[meow...@care2.com]

On Thursday, November 8, 2012 2:57:26 PM UTC, John Rumm wrote:
> On 08/11/2012 13:53, Mike Tomlinson wrote:
> > In article <Zr2dncYhfNDyeQfN...@brightview.co.uk>, John
> > Rumm <see.my.s...@nowhere.null> writes
> >
> >> http://s833.beta.photobucket.com/user/Elmer_BeFuddled/media/CounterfeitFuse.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.


NT

[meow...@care2.com]

Fusing on the neutral pole was banned here eons ago. A blown neutral fuse causes a faulty appliance to look dead, but be live.

A 10mm long fuse must have too low a breaking capacity to cope with more current than the breaker would act on. With the US fixed wiring system's lowish current breakers this shouldn't be a problem though.


NT

[meow...@care2.com]

On Friday, November 9, 2012 8:37:43 AM UTC, Doctor Drivel wrote:
> "David WE Roberts" <nos...@btinternet.com> wrote in message
> news:ag1s4u...@mid.individual.net...

> > "David Robinson" <davidrobinson> wrote in message

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

Nurse!


NT

[whisky-dave]

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


>
> --
>
> bert

[whisky-dave]

On Friday, November 9, 2012 8:37:43 AM UTC, Doctor Drivel wrote:

> "David WE Roberts" <nos...@btinternet.com> wrote in message
>
> news:ag1s4u...@mid.individual.net...
>
> >
>
> > "David Robinson" <davidr...@postmaster.co.uk> wrote in message
>
> > news:94667b91-ef5d-4c75...@k20g2000vbj.googlegroups.com...
>
> >> Not my question, or belief, but found here...
>
> >>
>
> >> http://forums.digitalspy.co.uk/showthread.php?t=1755197
>
> >>
>
> >>
>
> >> Is there a counter-argument?
>
> >
>
> >
>
> > Just to note that I've just replaced the 5A fuse in an extension lead for
>
> > the second time in a week.
>
> > Rated 4A coiled and 5A uncoiled.
>
> > We use it for lights but passing builders tend to plug anything into
>
> > anything.
>
> > So yes, the fuse does protect the cable :-)
>
>
>
> You are correct, but a little slower - it may go to 4A before the fuse
>
> breaks. If current is say 1A and the fuse 3A, then the current increases for
>
> whatever to 4A the fuse may not break so quick, but will eventually, so
>
> giving protection. 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 ?

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

>
> 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.

> They only time the current would be high enough to melt
>
> the flex would be if there is a fault, which would be momentarily and the
>
> fuse would then snap.

After a set time depending on the curretn flowing and the lengh of time.

> I "think" that is what is he on about. He says the
>
> 13A fuse will break faster on a fault than a 3A. BTW, I recall as a kid my
>
> sister's cheap Italian (looked good though) table lamp switch melting. It
>
> obviously had a "fault" and" a 13A fuse. A 3A fuse would have snapped
>
> stopping the melting,

fuses don;t snap they burn out.

>which was a fire hazard. The switch could be classed
>
> as a part of the cable and the appliance the light bulb.

could be if it were on the cable.

>
>
>
> 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.

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

That is not correct, you can't buy mains plug fuses in anti-surge.
Those sort are commom as internal fuses for protecting the equipment rahter than the cable.

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

[Mike Tomlinson]

In article <61ab985f-13f8-42db...@googlegroups.com>,
whisky-dave <whisk...@gmail.com> 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.

[whisky-dave]

So what fuse do you put in a fan that's rated at 50W a 3 amp ?
As that's what's in the fan we brought and it has been PAT tested and passed.

for me 50/230 is NOT 3
So are you saying I should put in a ~250ma fuse instead ?
As that's how I'd calculate it, but I'd put a 3 amp fuse in the plug as that's what the manufactuer did.

[charles]

In article <04b0a114-5d02-4044...@googlegroups.com>,

You forgot the switch on surge. the 50w is the running power

--
From KT24

Using a RISC OS computer running v5.18

[meow...@care2.com]

Exactly. There's also availability, and the fact that fuses below 3A often die of their own accord over time.


NT

[Mike Tomlinson]

En el artículo <04b0a114-5d02-4044...@googlegroups.com>,
whisky-dave <whisk...@gmail.com> escribió:

>So are you saying I should put in a ~250ma fuse instead ?

Use your common sense.

BS1362 fuses are not available in 250ma, so a 3A fuse would be the best
choice.

>As that's how I'd calculate it, but I'd put a 3 amp fuse in the plug as that's
>what the manufactuer did.

There you go then.

[polygonum]

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?

[1] I know they are not all actually meaningless, but to a large
proportion of end users of a lot of appliances, they might as well not
be there.

--
Rod

[whisky-dave]

On Friday, November 9, 2012 4:23:14 PM UTC, Mike Tomlinson wrote:
> En el artículo <04b0a114-5d02-4044...@googlegroups.com>,
>
> whisky-dave <whisk...@gmail.com> escribió:
>
>
>
> >So are you saying I should put in a ~250ma fuse instead ?
>
>
>
> Use your common sense.

Which would be wrong, because I as do others have to abide by the current ;-) legislation so calculating is less than half the battle.
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.

>
>
>
> BS1362 fuses are not available in 250ma,

yes I know and that's also why I said in another post ypou can;t use anit-surge

>so a 3A fuse would be the best
>
> choice.

Yep, which is NOT arrived at through a calculation which is the point.

>
>
>
> >As that's how I'd calculate it, but I'd put a 3 amp fuse in the plug as that's
>
> >what the manufactuer did.
>
>
>
> There you go then.

yep no calculation necessary

[whisky-dave]

On Friday, November 9, 2012 2:37:00 PM UTC, charles 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.

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

[charles]

In article <473510b6-b6a9-40d1...@googlegroups.com>,

I wouldn't calculate it. It needs to be measured. and no, I don't have
the correct meter for the job.

--

[Mike Tomlinson]

En el artículo <c4dc1fcb-6982-403f...@googlegroups.com>,
whisky-dave <whisk...@gmail.com> 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 :-)

[Mike Tomlinson]

En el artículo <ag4pao...@mid.individual.net>, polygonum
<rmoud...@vrod.co.uk> escribió:

>I can't help thinking that it would make sense for manufacturers to
>include "use a 3A plug fuse" on the rating plate.

I do see that sometimes, perhaps not on rating plates but in the user
manual that comes with the appliance.

It normally follows the plug wiring instructions and is worded something
along the lines of, "this appliance is supplied pre-fitted with a plug.
If it is necessary to fit your own plug, the brown wire must be
connected to the terminal coloured brown or marked L, the blue wire must
be connected to the terminal coloured blue or marked N, and the fuse
fitted must be rated at xA."

Because appliance flexes are so stupidly short nowadays and the 13A fuse
is universal (hello Mr Dyson, are you listening?), if I find myself
rewiring an appliance with a longer flex (hello Mr Dyson, I don't live
in a fucking rabbit hutch) I fit a lower-rated fuse in the plug to allow
for the increased wire resistance and therefore lower fault current to
ensure the fuse does blow under fault conditions.

But of course, elfin safety means we have to cater for the lowest common
denominator, so it's 6" flexes and 13A fuses all round.

[polygonum]

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.

--
Rod

[Bill Wright]

meow...@care2.com wrote:

>
> Exactly. There's also availability, and the fact that fuses
below 3A often die of their own accord over time.

If you use a mA fuse that's only barely adequate for the load there's
voltage drop across it.

Bill

[bert]

In message <61ab985f-13f8-42db...@googlegroups.com>,
whisky-dave <whisk...@gmail.com> writes

Take the empirical approach
--
bert

[bert]

In message <04b0a114-5d02-4044...@googlegroups.com>,
whisky-dave <whisk...@gmail.com> writes

3 amp as opposed to 5 amp or 13 amp.

--
bert

[bert]

In message <9e59009a-5be2-4d60...@googlegroups.com>,
meow...@care2.com writes

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

<Snip>
Fusing the neutral must be one of the most brainless ideas ever.
--
bert

[Jules Richardson]

On Fri, 09 Nov 2012 02:57:47 -0800, meow2222 wrote:

> On Thursday, November 8, 2012 11:28:43 PM UTC, Jules Richardson wrote:
>> On Wed, 07 Nov 2012 23:43:36 -0800, harry wrote:
>> > I think the 13a plug is the only one in the world with a fuse.
>> Fused plugs do exist here in the US, most often seen on Christmas tree
>> lights (the ones that are made here, rather than the China-built death
>> traps) - they have a little trapdoor in them for fuse access (US plugs
>> are tiny in comparison the the UK's chunk-o-rama ones :-) and a pair of
>> fuses that are around 10mm in length. cheers
>> Jules
>
> Fusing on the neutral pole was banned here eons ago. A blown neutral
> fuse causes a faulty appliance to look dead, but be live.

Yes, it ain't necessarily a good thing :-) I had a look at a couple of
strings of Chrimbo lights kicking around in the basement, and they're
both using 3A fuses.

> A 10mm long fuse must have too low a breaking capacity to cope with more
> current than the breaker would act on. With the US fixed wiring system's
> lowish current breakers this shouldn't be a problem though.

Well ours all seem to be rated at 15A or 20A (with a few at 30A for
things such as the cooker).

cheers

J

[John Rumm]

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




--
Cheers,

John.

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

[John Rumm]

On 08/11/2012 22:22, The Other Mike wrote:
> On Wed, 07 Nov 2012 22:44:35 +0000, John Rumm <see.my.s...@nowhere.null>
> 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.

[John Rumm]

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.

[John Rumm]

On 09/11/2012 16:29, polygonum wrote:
> On 09/11/2012 13:57, Mike Tomlinson wrote:
>> In article <61ab985f-13f8-42db...@googlegroups.com>,
>> whisky-dave <whisk...@gmail.com> 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!)

[polygonum]

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 <61ab985f-13f8-42db...@googlegroups.com>,
>>> whisky-dave <whisk...@gmail.com> 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

[meow...@care2.com]

On Friday, November 9, 2012 8:20:01 PM UTC, bert wrote:
> In message <9e59009a-5be2-4d60...@googlegroups.com>,
> 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

[meow...@care2.com]

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

[Doctor Drivel]

"whisky-dave" <whisk...@gmail.com> wrote in message
news:d05107dd-aadc-4916...@googlegroups.com...

>> 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.

[whisky-dave]

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.

[whisky-dave]

On Thursday, November 22, 2012 10:48:18 AM UTC, Doctor Drivel wrote:
> "whisky-dave" <whisk...@gmail.com> wrote in message
>
> news:d05107dd-aadc-4916...@googlegroups.com...
>
>
>
> >> 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.

[Doctor Drivel]

"whisky-dave" <whisk...@gmail.com> wrote in message

news:2f978a74-8709-4b09...@googlegroups.com...

>> ..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.

[Doctor Drivel]

<meow...@care2.com> wrote in message
news:6adb6806-a360-4ff2...@googlegroups.com...

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

This man is mad.

[charles]

In article <7cf516c4-340a-4a13...@googlegroups.com>,

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

[Dave Plowman (News)]

In article <52f29ae6...@charleshope.demon.co.uk>,

charles <cha...@charleshope.demon.co.uk> 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 da...@davenoise.co.uk London SW
To e-mail, change noise into sound.

[Dave Plowman (News)]

In article <k8l6gt$t1o$1...@dont-email.me>,

Doctor Drivel <inv...@not-for-mail.invalid> 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.

[charles]

In article <52f2a36...@davenoise.co.uk>,

Dave Plowman (News) <da...@davenoise.co.uk> wrote:
> In article <52f29ae6...@charleshope.demon.co.uk>,
> charles <cha...@charleshope.demon.co.uk> 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.

[Doctor Drivel]

Dave Plowman (News) wrote:
> In article <k8l6gt$t1o$1...@dont-email.me>,
> Doctor Drivel <inv...@not-for-mail.invalid> 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.

[The Other Mike]

On Thu, 22 Nov 2012 13:53:44 +0000 (GMT), "Dave Plowman (News)"
<da...@davenoise.co.uk> wrote:

>In article <k8l6gt$t1o$1...@dont-email.me>,
> Doctor Drivel <inv...@not-for-mail.invalid> 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 :)


--

[meow...@care2.com]

On Thursday, November 22, 2012 1:58:34 PM UTC, Dave Plowman (News) wrote:
> In article <k8l6gt$t1o$1...@dont-email.me>,
> Doctor Drivel <inv...@not-for-mail.invalid> 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

[John Rumm]

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.