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Topic Title: Fused plugs in UK, why not in the rest of Europe?
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Created On: 02 May 2010 09:56 AM
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 05 May 2010 10:39 PM
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westfield6

Posts: 169
Joined: 12 October 2007

Originally posted by: Jaymack

Originally posted by: gkenyon

Originally posted by: Jaymack



It would be feasible to design an interlocking system with the switch/plug, so that the switch is in the OFF position before a plug is withdrawn; and to ensure a plug is inserted before the switch can be placed in the ON position. Motivation would be required though for an individual manufacturer to adopt such a design and risk losing market share, this would have to be adopted in the standards.



Regards


Indeed, and back in the late '50s such sockets existed in BS546 5A and 15A versions. The earth pin opened the interlock which enabled the switch to be turned on. Once on a spike of some sort dug into the earth pin so that the plug could not be removed. These sockets were huge DC rated things and were installed in the classrooms at school. Being inquisitive teenagers we quickly discovered that inserting a thin pencil in the earth socket enabled us to turn on the switch. If the pencil was thin enough it could be removed without too much damage.
 05 May 2010 10:59 PM
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daveparry1

Posts: 7407
Joined: 04 July 2007

I haven't been following this thread that much and haven't read all the posts but I was just wondering how many here remember the DS plugs (live pin was the fuse) that were around in the 50's & early 60's? Sorry if this is out of context but just curious as no-one I know seems to remember them!
Dave.
 05 May 2010 11:27 PM
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Angram

Posts: 625
Joined: 23 March 2009

Yes,
I found one once in an odds and sods box in a store room.
I always thought the end cap might come off with excessive use; did they ever ?
 06 May 2010 02:26 PM
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Deuchar

Posts: 59
Joined: 25 July 2008

Originally posted by: OMS

It's the responsibility of designers to take a holistic view on whatever they're designing as far as I'm concerned. To design, then market any product or commodity, without a proper macroscopic viewpoint in regard to social engineering and the consequences of injuries, being sued or prosecuted is irresponsible, - if it can happen it will.

I disagree - engineers only have limited duties to thier clients generally.

If we take you comments literally then we wouldn't design anything.

OMS


Let's not forget that there is ethical guidance for engineers, here is an extract from the "Statement of Ethical Principles" developed by the Royal Academy of Engineering:

"The Royal Academy of Engineering, in collaboration with Engineering Council (UK) and a number of the leading professional engineering institutions, has created a Statement of Ethical Principles to which it believes all professional engineers and related bodies should subscribe.

Professional Engineers work to enhance the welfare, health and safety of all whilst paying due regard to the environment and the sustainability of resources. They have made personal and professional commitments to enhance the wellbeing of society through the exploitation of knowledge and the management of creative teams."
 06 May 2010 02:41 PM
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OMS

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Yes, I've read the statement of ethical principles along with all the other aspirational stuff like not damaging the environment etc etc ad infinitum.

My point was whilst we may like to think that we could comply in truth most of us can't. Globalisation of the market place and displacement from clients almost certainly means that it's almost impossible for engineers to determine who they owe duties to - and at what level those duties are owed.

Regards

OMS

-------------------------
Let the wind blow you, across a big floor.
 06 May 2010 04:11 PM
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AJJewsbury

Posts: 13929
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OMS has a point. A few years ago I remember that one member (not me!) of a certain professional institution (not the IET, but not dissimilar) pointed out a clause in the Society's constitution that demanded that members did no harm to society (or words to that effect) and asked if this mean that they should refuse membership to those that worked for tobacco companies. The learned society disagreed but when challenged could only issued lots of words, none of which appeared to marry up their policy with their constitution...
- Andy.
 06 May 2010 04:27 PM
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OMS

Posts: 21094
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And it's not just tobacco Andy - chemical, oil and gas, agri chemicals, defense, armaments, building services, medical engineering and a host of other sectors are have potential to create harm and are sectors in which many engineers work.

The publication by John Uff on behalf of the RAENG is an interesting read

Regards

OMS

-------------------------
Let the wind blow you, across a big floor.
 06 May 2010 04:43 PM
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Deuchar

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Originally posted by: OMS

Yes, I've read the statement of ethical principles along with all the other aspirational stuff like not damaging the environment etc etc ad infinitum.

My point was whilst we may like to think that we could comply in truth most of us can't. Globalisation of the market place and displacement from clients almost certainly means that it's almost impossible for engineers to determine who they owe duties to - and at what level those duties are owed.OMS


But is that not being rather defeatist? Surely Jaymack is correct in his original point re an holstic view, to do otherwise is to encourage anarchy!
 06 May 2010 04:54 PM
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OMS

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Not defeatist no - just the practical reality of working in global engineering - many of us don't get the chance to pick and choose the client, the project or the location to be fair.

So the ethics does tend tend to take on a fair amount of "when in Rome............".

I didn't disagree with Jaymacks comments - I merely pointed out that the rhetoric and the practical reality are often divergent - and if they were honest, the institutions would actually acknowledge that fact

Regards

OMS

-------------------------
Let the wind blow you, across a big floor.
 06 May 2010 05:51 PM
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gkenyon

Posts: 4703
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We've already lost our way in the electrical industry.

I can buy a table lamp, and put it on my bedside table.

My two-year-old could climb on our bed, unscrew (or push, twist and remove) the lamp.

Then switch it on, and insert fingers !

How dangerous - yet we still are allowed to sell these products !!!


How do I know this?

When I was 18 months old, I did just that, woke up my dad screaming and looking at little black marks on two adjacent fingers!



The corollary: could it be that we are really taking the safety thing too far?

(Or alternatively, we need to ban many types of screw and bayonet lampholders ! )

-------------------------
EUR ING Graham Kenyon CEng MIET TechIOSH
Principal and Proprietor,
G Kenyon Technology

Web-Site: www.gkenyontech.com
 06 May 2010 07:39 PM
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maxheidi

Posts: 2
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Hi,

I went to wholesalers in Northern Sweden for some socket as we were rewiring to be asked ' is it a new house or an old house?'

'Whats thats got to do with it? ' I asked

The reply was 'old houses dont have earth just 2 pins new have earth so 3 pins'

It s quite layed back and many labour saving ideas, when I am in the shower and I want the heating on just reach and turn on the 3 ph pump, its nice and warm when you get out if it goes wrong you still end warm!

Might brighten your day!
 06 May 2010 08:27 PM
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gkenyon

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Anyone want to explain about Scandinavia and Class 0 then ?

-------------------------
EUR ING Graham Kenyon CEng MIET TechIOSH
Principal and Proprietor,
G Kenyon Technology

Web-Site: www.gkenyontech.com
 07 May 2010 01:32 PM
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AJJewsbury

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Anyone want to explain about Scandinavia and Class 0 then ?

Sounds like some continental installs I've seen (Shucko sockets) - earth contacts on sockets on in "wet" rooms - bathrooms and kitchens - others just L&N (but will accept earthed plugs). Not unlike section 418.1 in our book I think (or 418.2 if you have several appliances on an extension lead).

- Andy.
 28 February 2016 09:28 AM
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Ietsurfer

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"The UK is therefore stuck with large, heavy and expensive plugs which are a safety hazard in there own right:
1) Many accidents have occured where people have lifted an appliance down off a shelf or cupboard and have been struck, often in the eye, by the plug.
2) The plug will normally lie on the floor pins up. Most of us will have steped on one at some time.
3) The fuse connections tend to overheat, especially with cheap plugs on high loads. This has resulted in the live pin remaining in the socket as the plastic surounding it has been degraded by the heat."


The UK plug is the safest design in the world because:
1. The earth pin is longest it goes in first and comes out last
2.The earth pin fatter is than the rest therefore it cannot get inserted in to the L or N socket
3. The plug cannot be inserted the wrong way round
4. The plug is fused
5. The cover cannot be removed while plugged in as screws are on the other side
6. If manufactured correctly to the BS1363 standard will not overheat and will withstand 13A. Excess current will blow the fuse and safely cut off the current.
 28 February 2016 12:03 PM
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joepostle

Posts: 97
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Well said letsurfer. Personally I like the discrimination the plug fuse provides between the appliance the mains. Equally I like the idea & convinience of the mini-mcb idea (thought of the idea years ago!) protecting from user 'errors' in a similar manner to MCBs in DBs.
 28 February 2016 03:55 PM
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AJJewsbury

Posts: 13929
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Just in the interests of balance. (or debate or just playing Devil's Advocate!)....

The UK plug is the safest design in the world because:
1. The earth pin is longest it goes in first and comes out last

Although an earth that makes first and breaks last is common to just about every plug/socket design in the world - either via a longer pin, contacts recessed less deeply (so same length pin still makes contact first) or scraping earth contact on the body of the plug.

2.The earth pin fatter is than the rest therefore it cannot get inserted in to the L or N socket

Again, most designs achieve the same effect, if not by pin shape (e.g. US) or scraping (Shuko) then by socket geometry. In a similar vein, there's a flaw in BS 1363 for extension lead sockets that allows the earth pin to be put into the socket with the plug upside down so opening the shutters without the L & N contacts being covered by the plug

3. The plug cannot be inserted the wrong way round

Not an issue with modern appliances and an a.c. supply...

4. The plug is fused

Not an issue where lower rated final circuits are used. The fuse also creates heat which can aggrevate other problems. Also means the plug shouldn't be used on systems where the neutral isn't earthed (e.g. small generators).

5. The cover cannot be removed while plugged in as screws are on the other side

Most european designs achieve the same by having the plug inside a recess in the socket which holds the two halves together when plugged in.

6. If manufactured correctly to the BS1363 standard will not overheat and will withstand 13A. Excess current will blow the fuse and safely cut off the current.

That's not entirely true - if you want to use a 13A plug/socket for the full 13A for a long duration (e.g. for electric vehicle charging) BS 7671 demands you get the manufactuer's specific approval for such a use as the basic BS 1363 tests aren't sufficient. (Partly the problem is the heat produced by the fuse...)

Also discrimination with the ring circuit protective device has practically disappeared for faults since the introduction of MCBs.

For all that I do still rather like the BS 1363 plug!
- Andy.
 28 February 2016 04:45 PM
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rocknroll

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1) Many accidents have occured where people have lifted an appliance down off a shelf or cupboard and have been struck, often in the eye, by the plug.

My dear ole granny used to say when I was doing something, "stop doing that or you'll have your eye out.

I remember once dragging a circular saw of a shelf and at the same time the jigsaw came as well and bounced off my nut, hurt for weeks with a big bump. Not been right since LOL.

I think banging your toe on the bed or piece of furniture when you get up for a widdle is worse than treading on a plug.

regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 28 February 2016 06:39 PM
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Zoomup

Posts: 2211
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"That's not entirely true - if you want to use a 13A plug/socket for the full 13A for a long duration (e.g. for electric vehicle charging) BS 7671 demands you get the manufactuer's specific approval for such a use as the basic BS 1363 tests aren't sufficient. (Partly the problem is the heat produced by the fuse...)"

I have come across 13 Amp fuses in fused connection units supplying immersion heaters.They can get a little warm in use, but generally they seem to dissipate the heat away without problems.

A 13 Amp plug, fitted with a 13 Amp fuse supplying a 13 Amp load, can lose its heat by conduction or convection when fully loaded. The B.S. 1362 13 Amp fuse is thermally connected to a big brass plug pin and a good copper flex, albeit by a short terminal link in the case of the flex. Both of these offer good heat sinks for the low resistance fuse element.

Just how much heat does a 13 Amp fuse generate when fully loaded. What is its resitance when in use? Less than 0.1 I would say.

Long live the 13 Amp plug.

Z.
 28 February 2016 08:21 PM
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ectophile

Posts: 637
Joined: 17 September 2001

6. If manufactured correctly to the BS1363 standard will not overheat and will withstand 13A. Excess current will blow the fuse and safely cut off the current.


So what happens if you take a standard 4-way extension lead and plug in two kettles full of water?

You get two kettles of boiling water. A 13A fuse will happily pass 20A for long enough to boil a kettle. I've seen it done.

-------------------------
S P Barker BSc PhD MIET
 28 February 2016 09:44 PM
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AJJewsbury

Posts: 13929
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Just how much heat does a 13 Amp fuse generate when fully loaded. What is its resitance when in use? Less than 0.1 I would say.

So I2R comes out at 16.9W? (by way of extreme comparison - how hot can a 16W soldering iron get?)

I have come across 13 Amp fuses in fused connection units supplying immersion heaters.They can get a little warm in use, but generally they seem to dissipate the heat away without problems.

Entirely true, but equally there have been other ones that also comply with BS 1363 and have had problems (just search the forum for several examples).

- Andy.
IET » Wiring and the regulations » Fused plugs in UK, why not in the rest of Europe?

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