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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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 02 May 2010 09:56 AM
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Greeny

Posts: 4
Joined: 14 March 2010

Hi All,

In the Uk we accept that for protection of cables we use protective devices. We also have fused plugs, which for instance might be 3 amps on a low current using device such as a mains radio. The 3 amp fuse is going to be safer and offer a level of secuity to the radio, and maybe a simple fault on it could be rectified instead of the whole thing going up in flames if there was no fused plug.



WHY is it that in Europe they do not have fused plugs and rely on the mcbs ?

I would welcome others comments.

Thanks

Greeny
 02 May 2010 11:31 AM
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gel

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Imagine closely related to fact that we unlike Europe, and just about anywhere else, use the ring main system.

-------------------------
Gel__Big Brother is here
 02 May 2010 02:23 PM
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ebee

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Using Ring Mains has nowt to do with it.

Using Ring Final Circuits might have though

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 03 May 2010 09:23 AM
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rogerbryant

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Turning the question round, why does the UK use fused plugs?

A decision was taken to try to save installation costs by installing a ring final circuit with the sockets distributed allong it. As this one circuit could be supplying a complete small house a fuse rating of 32A with 2.5mm2 (or strictly 7/0.29) conductors was decided on. This did not offer protection to existing small flexible cords so a protective device was required in the plug. The rating of this device was 13A to allow a load of 3kW at 230V. Various smaller ratings were supplied though currently only 3A is recognised.
As it is impossible to ensure that a lower rated fuse will be fitted if required (fuses are interchangable and are fitted by laymen) it was also determined that a 13A fuse will offer short circuit protection to a 0.5mm2 flexible cord of restricted length. Overload protection was deemed to be a requirement of the appliances and was put in the product standards for them.

In this case the product standards require an appliance to be 'safe' when protected with a 13A fuse. As there is very little difference or discrimination between a 13A fuse and a 10A or 16A circuit protective device as used in Europe they meet the same safety requirements with a radial per room or group of small rooms protected by a 10A or 16A device and using unfused plugs.

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.

Europe has much smaller, lighter plugs which avoid all these problems and allow for a more compact installation. Typically 3 sockets can be fitted into the same space as one UK type. They have also ended up with the almost universal 2 pin Europlug for smaller appliances.

Just my 0.02EUR worth.

Best regards

Roger
 03 May 2010 10:03 AM
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gkenyon

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Roger,

One thing missing from your post, I think.

The arrangement in the UK permits appliances connected with 0.5 sq mm flex to be safely connected to the same power circuit, because the plug can be fitted with a 3A or 5 A fuse (as per Tables in BS1363).

We therefore don't need additional 6A small power circuits.

I'm understand that 0.5 sq mm flex is not adequately protected against short-circuits for all conditions in the UK, from 16A and 20 A mcb's.

-------------------------
Eur Ing Graham Kenyon CEng MIET TechIOSH
 03 May 2010 11:33 AM
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Inrush

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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.


You can't design for idiocy
 03 May 2010 12:23 PM
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gkenyon

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Originally posted by: Inrush
You can't design for idiocy
Tongue-in-cheek this statement may be, and standards committees often say their standards don't account for mis-use, but more & more frequently these days, for one reason or another (typically fear of being sued, or prosecuted under H&S legislation), it seems we're being asked to do just that more and more these days.

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Eur Ing Graham Kenyon CEng MIET TechIOSH
 03 May 2010 04:39 PM
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rogerbryant

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Graham,

The system I am most familiar with, Switzerland, has a maximum 10A circuit protection device for the 'normal' domestic outlets which also accept the Europlug. Germany, and I believe France, have a maximum rating of 16A. These countries do not use additional 6A circuits or outlets.
I have seen two different sizes of the Italian plug (with the pins all in a line) which I think may be 10A and 16A but I don't know the circuit details.
I believe that the 0.5mm2 flex is protected against short circuits by a 16A opd (MCB or bottle fuse) but like you say I doubt if a 20A device would be suitable under all conditions.

Best regards

Roger
 03 May 2010 06:22 PM
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Angram

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There was a serious attempt at specifying a "universal plug" standard some years ago.
I don't think anyone anywhere was keen to have another standard to deal with.
There were pictures of the proposed plug I think.

Large rated appliances are hard wired in some countries aren't they?
They stay as part of the property when folks move house.
So they don't need 3.2 kW plugs and can increase diversity in their radials.

Does a round pin make a more reliable connection than a square one?

Terence.
 03 May 2010 06:31 PM
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gkenyon

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Roger,

Whilst I understand that some countries use the arrangements you describe for appliances with 0.5 sq mm flex, hence my italics in previous post, I'm not sure that in the UK we agree with the fact that 0.5 sq mm flex is protected by 16A OPD (in fact 13A, neither by 13A BS1362).

As a quick get-out, I refer to Section 6.8 of and Figure 6.10 of Paul Cook's "Commentary on IEE Wiring Regulations. 16th Ed BS7671: 2001".

However, if memory serves from calculations I've carried out myself in the past, I believe that a 16A mcb may well offer better protection than a BS1362 fuse in some parts of the magnetic region; but there is a "dubious region" where the 16A Type B does not offer protection , with both adiabatic and non-adiabatic calculations, in some regions of the worst-case mcb curves.

-------------------------
Eur Ing Graham Kenyon CEng MIET TechIOSH
 03 May 2010 10:52 PM
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westfield6

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Originally posted by: rogerbryant

Typically 3 sockets can be fitted into the same space as one UK type.



Really! The most common 3 pin connectors in Europe are the Schuko type, either the German version with side contacts for earth of the French version with an earth pin in the sockets. I fail to see how even 2 of these could be fitted in the space of a BS1363 socket let alone 3. Yes you might get 3 two pin sockets in that space, but that is hardly comparing like with like.

Incidently BS1363 sockets are also used in Ireland, Malta, Gibraltar, and Cyprus within Europe so we are not unique.
 04 May 2010 10:01 AM
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rogerbryant

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Terence,

The larger appliances, cookers, washing machines, etc are often run from dedicated 3 phase radials, sometimes with plug and socket, otherwise hard wired like UK cookers. There is also a much greater tendency to have centralised heating systems (and better insulation in the colder regions) so plug in heaters are not common.
I believe that the use of multiple 3kw electric fires was another reason given for the UK ring final circuit.

Graham,

I agree that there are some areas where the theory suggests that there will be problems, the same also applies to an unequally loaded ring final circuit, but in reality there do not seem to be any significant issues. This is probably due to the fairly high factor of safety (or ignorance) in most electrical distribution systems. Short circuit ratings are if I remember correctly based on a conductor temperature of 160C for PVC. The cable will not fail instantly at 161C and will probably survive 170C or even 180C before the conductor starts to migrate.

Westfield6

I could not find a picture of the outlet I had in mind, but here is a 4 way Schuko in a 108 x 98 housing. I believe a UK single 13A socket is typically 86mm square.

http://www.schaltertresen.de/i...4fach_6604.02_Si.html

Best regards

Roger
 04 May 2010 10:26 AM
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gkenyon

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Of course, there is no reason why the fuse in the plug top needs to be in the plug top.

It could be in the socket.

Still permits RFCs to be used.

But still unsure about 0.5 sq mm flex.

As Roger says, what's the actual risk? I'll need to repeat the calcs to look at that, I think.

-------------------------
Eur Ing Graham Kenyon CEng MIET TechIOSH
 04 May 2010 12:40 PM
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iansettle

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Originally posted by: gkenyon

Of course, there is no reason why the fuse in the plug top needs to be in the plug top.



It could be in the socket.


Still permits RFCs to be used.



But still unsure about 0.5 sq mm flex.



As Roger says, what's the actual risk? I'll need to repeat the calcs to look at that, I think.


Not a very good idea as what if the was a 3A fuse in the socket and a 13A appliance was plugged in?
 04 May 2010 01:53 PM
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Jaymack

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Originally posted by: iansettle
Originally posted by: gkenyon
Of course, there is no reason why the fuse in the plug top needs to be in the plug top.
It could be in the socket.
Still permits RFCs to be used.
But still unsure about 0.5 sq mm flex.
As Roger says, what's the actual risk? I'll need to repeat the calcs to look at that, I think.

Not a very good idea as what if the was a 3A fuse in the socket and a 13A appliance was plugged in?

Bang! - call an electrician.
Agree with the reasoning (a la fusewire), though the same limitation exists for replacing fuses in plugs.

Regards
 04 May 2010 02:16 PM
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Pactrol

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yes the 13A plug has its faults but why has no one re designed it like the euro plug but retaining the square pins & fuse so it can,t lay on the floor with pins up waiting to be stood on Ouch!!!
 04 May 2010 03:08 PM
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gkenyon

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Originally posted by: Jaymack

Originally posted by: iansettle

Originally posted by: gkenyon

Of course, there is no reason why the fuse in the plug top needs to be in the plug top.

It could be in the socket.

Still permits RFCs to be used.

But still unsure about 0.5 sq mm flex.

As Roger says, what's the actual risk? I'll need to repeat the calcs to look at that, I think.


Not a very good idea as what if the was a 3A fuse in the socket and a 13A appliance was plugged in?


Bang! - call an electrician.

Agree with the reasoning (a la fusewire), though the same limitation exists for replacing fuses in plugs.



Regards
Yes, and FCUs - we use this arrangement already. Are you saying it's unsafe?

There's no reason the "fuse" needs to be a BS1362 either - what about a mini-mcb, the type found in appliances and certain outlets?

There are two lines of thought:

1. If as Roger suggests, we feel confident to protect 0.5 sq mm by a 10A or 16A OPD (I'm not suggesting this personally, just discussing), then there is only one OPD type, and not a problem - it could be a mini-mcb too, to prevent "polo-wrapper man" from "foiling the protection"

2. Or we accept that we need "13A" and "5A" outlets, so we have a new socket design, which has one earth receptable, one neutral receptable, and two phase receptacles, say 5A with round pin and 13A say 4-5 mm away with square pin. Each as a separate OPD in the socket. Won't be £1.50 each though !

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Eur Ing Graham Kenyon CEng MIET TechIOSH
 04 May 2010 03:24 PM
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AJJewsbury

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why has no one re designed it like the euro plug but retaining the square pins & fuse so it can,t lay on the floor with pins up waiting to be stood on Ouch!!!

I understood that having the flex at 90-degrees to the pins was meant to be a safety improvement in that it discouraged people from unplugging by tugging on the flex, but had to grab the plug properly - hence avoiding lots (possibly more dangerous) problems with wires coming adrift when the cord grip eventually gives up. I guess you can't win them all!

There are some "schuko" moulded plugs with the cord coming out of the bottom - BS 1363 style.

There was a serious attempt at specifying a "universal plug" standard some years ago.

I think there's a de-facto standard emerging - the IEC 60320 C13/14 (a.k.a. "kettle connectors") (and C19/20 for 16A) - already in common use not just throughout Europe but across the world - on 115V as well as 230V systems. It's graduated from just an appliance inlet to equipment distribution (e.g. IT racks, computer extension leads) - 'to the wall' would be a logical next step.

- Andy.
 04 May 2010 04:26 PM
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gkenyon

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Originally posted by: AJJewsbury
I think there's a de-facto standard emerging - the IEC 60320 C13/14 (a.k.a. "kettle connectors") (and C19/20 for 16A) - already in common use not just throughout Europe but across the world - on 115V as well as 230V systems. It's graduated from just an appliance inlet to equipment distribution (e.g. IT racks, computer extension leads) - 'to the wall' would be a logical next step.
Andy,

Not sure about this too. Whilst it appears logical, the big problem I see is that the Installation Overvoltage Category of the IEC60320 C13/C14 is not compatible with being part of the fixed wiring installation - only for use "after socket or connection unit".

I think the same also applies to the C15/16, C17/18 and C19/20 connectors.

That is, unless we install PDUs similar to IT racks, that is . . .

-------------------------
Eur Ing Graham Kenyon CEng MIET TechIOSH
 04 May 2010 06:48 PM
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Jaymack

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Originally posted by: gkenyon

Yes, and FCUs - we use this arrangement already. Are you saying it's unsafe?


The possibility is always there for say a 13A replacement fuse for say a 3A. The general public is not too clever on electrics, they should be protected from themselves - foolproof as far as possible where cost will allow. The design, despite the failings will be around for a long time, economics and a reaction to inconvenience will prevail; unless there's a major justification for change.
There has been one major modification over the years that I'm well aware of - the sleeving of the live pins, (my son of 3 years then, pushed a yale key down behind a live plug).
In the 60's, there was also doubt on the ability of the plug/socket to handle the 13A rating continuously, I remember one authority recommended withdrawing and re-inserting the plugs to keep the plugin connections clean, maybe the standards have been uprated in this regard.

Regards
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