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Topic Title: Fuses in IEC leads
Topic Summary: What is the maximum fuse rating for an IEC lead?
Created On: 29 May 2009 11:08 AM
Status: Read Only
Linear : Threading : Single : Branch
 Fuses in IEC leads   - RobinBarton - 29 May 2009 11:08 AM  
 Fuses in IEC leads   - AJJewsbury - 29 May 2009 10:41 PM  
 Fuses in IEC leads   - timjames2 - 30 May 2009 12:10 AM  
 Fuses in IEC leads   - gkenyon - 30 May 2009 02:08 PM  
 Fuses in IEC leads   - perspicacious - 30 May 2009 04:04 PM  
 Fuses in IEC leads   - davyn1 - 30 May 2009 05:50 PM  
 Fuses in IEC leads   - timjames2 - 31 May 2009 12:05 AM  
 Fuses in IEC leads   - timjames2 - 31 May 2009 12:26 AM  
 Fuses in IEC leads   - gkenyon - 03 September 2009 05:14 PM  
 Fuses in IEC leads   - davyn1 - 31 May 2009 08:32 AM  
 Fuses in IEC leads   - Baz - 31 May 2009 02:14 PM  
 Fuses in IEC leads   - perspicacious - 31 May 2009 02:58 PM  
 Fuses in IEC leads   - alancapon - 31 May 2009 03:50 PM  
 Fuses in IEC leads   - Angram - 03 September 2009 10:32 PM  
 Fuses in IEC leads   - perspicacious - 03 September 2009 11:02 PM  
 Fuses in IEC leads   - gkenyon - 04 September 2009 09:34 AM  
 Fuses in IEC leads   - sparkingchip - 06 September 2009 11:57 AM  
 Fuses in IEC leads   - sparkingchip - 06 September 2009 12:03 PM  
 Fuses in IEC leads   - sparkingchip - 06 September 2009 12:16 PM  
 Fuses in IEC leads   - gkenyon - 06 September 2009 02:58 PM  
 Fuses in IEC leads   - Angram - 06 September 2009 02:38 PM  
 Fuses in IEC leads   - sparkingchip - 06 September 2009 03:07 PM  
 Fuses in IEC leads   - anastasis - 06 September 2009 03:17 PM  
 Fuses in IEC leads   - sparkingchip - 06 September 2009 03:18 PM  
 Fuses in IEC leads   - sparkingchip - 06 September 2009 04:39 PM  
 Fuses in IEC leads   - sparkingchip - 06 September 2009 04:46 PM  
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 29 May 2009 11:08 AM
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RobinBarton

Posts: 6
Joined: 07 November 2002

If you have a lead with a 13A plug and an IEC socket (which is rated at 10A), surely the maximum rating of fuse in the plug is 10A as a large proportion of IEC inlets are not fused. A lead with a 13A fuse should, surely, fail a visual inspection?

Am I wrong?

I queried this with my supplier (as their leads are all supplied with 13A fuses). Their response was that it is to do with inductive loads and the associated inrush current. I cannot work this one out myself - surely a 10A BS1362 fuse would withstand the inrush of most 10A inductive loads.

If I install a 32A 60309 outlet on a wall - I have to protect it with a 32A breaker, regardless of the load (although I can choose the breaker type with respect to inrush currents etc). So how come these leads can be supplied with 13A fuses...?
 29 May 2009 10:41 PM
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AJJewsbury

Posts: 17795
Joined: 13 August 2003

If I install a 32A 60309 outlet on a wall - I have to protect it with a 32A breaker

Ah, but if you install several 16A ones, you can supply them all from a 20A breaker...

- Andy.
 30 May 2009 12:10 AM
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timjames2

Posts: 120
Joined: 17 January 2006

This has been a source of confusion for many years.

The IEC socket is rated at 10A, but most IEC leads supplied with equipment are fitted with 0.75mm cable, which is (nominally)rated at 6A. Hence, you would expect to see a 5A fuse, and this is what is normally fitted.

However, BS1362 only now recognises 2 values of plug top fuse, stating that a 3A fuse should be fitted to an appliance of less than 700W and a 13A fuse to an appliance bigger.

Consequently, it is not uncommon to find brand new IEC cables fitted with 13A fuses.

Unfortunately the suppliers are not much help - I queried this with Dell once (they supply 13A fuses in their IEC leads and the guy on their technical desk had little clue about it.)

The situation is slightly confused by some manufacturers who fit 10A IEC sockets to high powered appliances, and supply 1.0mm IEC cables fitted with 10A fuses! (I tested a 2000W Power Amplifier today with this very cable)

The user of said appliance had a rack full of DJ equipment and a box full of leads. He never uses the same lead twice. If I had changed all of his IEC cables to 5A fuses (apart from the thicker one) he would have at some point used a 5A one with the amp and blown the fuse half way through his DJ set. That's when you find the fuse has been replaced with a bolt or a piece of silver foil!

The ony sensible approach is to pass the lead on a visual inspection if it has a 5, 10 or 13A fuse in.

It's got nothing to do with inrush currents or inductive loads - more to do with cost (13A fuses are cheap) and the fact that BS1362 has been simplified for the general public and therefore is slightly at odds with BS7671.

Fail all the IEC cables with silver paper wrapped around the fuse, the ones with nicks, squashed and damaged cable, the leads joined with insulating tape, and all those with cracked plugs or non-sleeved pins, and you'll be fine.

-------------------------
Tim James
PAT Testing Expert Ltd

PAT Testing Course
 30 May 2009 02:08 PM
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gkenyon

Posts: 5354
Joined: 06 May 2002

It's 13A.

From UK perspective, the plug fuse protects the flexible cord, and nothing else. The following standards/rules are in place, as per Plugs & Sockets Regulations:

1. BS1362 itself says that the preferred values for the plug fuse are 3A and 13A

2. BS1363-1 says that you size the plug top fuse off the CABLE SIZE - 0.5 sq mm is 3 A fuse, except some large inrush appliances where 5A is acceptable. 0.75 and greater is 13A.


Don't get too hung up on the rating of the socket outlet in particular - in other EU countries, the socket outlet on the wall, feeding the UNFUSED plug end of the lead will be fed from 16A or 20A mcb.


So, who is supposed to look at the rating of the outlet, you'll ask?
Answer: the designer of the appliance the outlet feeds !

-------------------------
EUR ING Graham Kenyon CEng MIET TechIOSH
G Kenyon Technology Ltd

Web-Site: www.gkenyontech.com
 30 May 2009 04:04 PM
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perspicacious

Posts: 8055
Joined: 18 April 2006

"Fail all the IEC cables with silver paper wrapped around the fuse, the ones with nicks, squashed and damaged cable, the leads joined with insulating tape, and all those with cracked plugs or non-sleeved pins, and you'll be fine.
-------------------------
Tim James
PAT Testing Expert"


Is this a fail in the CoP?

Regards

BOD
 30 May 2009 05:50 PM
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davyn1

Posts: 2870
Joined: 01 August 2004

unsleeved pins is not retrospective so not a fail
also
However, BS1362 only now recognises 2 values of plug top fuse, stating that a 3A fuse should be fitted to an appliance of less than 700W and a 13A fuse to an appliance bigger.
the COD recommends the fuse recomended by the manufacturers be used ??
the COD just says 3/13A are generaly used,and remember the fuse in the plug top is to protect the cable not the appliance
davy

-------------------------
just because i'm paranoid doesn't mean theyre not out to get me

Edited: 30 May 2009 at 10:45 PM by davyn1
 31 May 2009 12:05 AM
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timjames2

Posts: 120
Joined: 17 January 2006

BOD - good point well made.

You're right in the issue of unsleeved pins is not retrospective. Personally I feel it should be - BS1363 was updated in the 1970's because plugs without sleeving were considered dangerous, and even now we occassionally hear of injuries and deaths from plugs with unsleeved pins. I also believe that seatbelts should be fitted to all cars, even those manufactured before they became law (also not retrospective but should be!)

I'm not sure how long IEC leads have been around, but I'm sure they came along AFTER BS1363 required sleeving on the pins. Therefore, any IEC cable fitted with a non-sleeved plug WOULD fail because it shouldn't have been put on in the first place.

The Plugs and Sockets Regs require any plug being fitted to meet the CURRENT version of BS1363, whereas the other regs only require the plug to have met the standards when it was manufactured.

Hence it is permitted to pass a plug which meets an earlier version of the standards, but it is not permitted to take a plug off and refit it unless it meets the current standard.

-------------------------
Tim James
PAT Testing Expert Ltd

PAT Testing Course
 31 May 2009 12:26 AM
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timjames2

Posts: 120
Joined: 17 January 2006

A little research shows the following:-

IEC connectors are defined in IEC320 / BSEN60320 - the earliest version of this standard I can find is 1987.

The Plugs and Sockets regulations require a plug fitted to a new appliance to comply with BS1363:1984 - which does require insulation on the pins. I'm not sure, but I believe that the requirement to sleeve the pins was in BS1363:1973, although I am prepared to be corrected on this. It was definitely a requirement of the 1984 standard.

Therefore, I believe it is correct to say that ALL IEC cables should have sleeved pins on the plug tops.

I really should get a life.....

-------------------------
Tim James
PAT Testing Expert Ltd

PAT Testing Course
 03 September 2009 05:14 PM
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gkenyon

Posts: 5354
Joined: 06 May 2002

Originally posted by: timjames2

A little research shows the following:-



IEC connectors are defined in IEC320 / BSEN60320 - the earliest version of this standard I can find is 1987.



The Plugs and Sockets regulations require a plug fitted to a new appliance to comply with BS1363:1984 - which does require insulation on the pins. I'm not sure, but I believe that the requirement to sleeve the pins was in BS1363:1973, although I am prepared to be corrected on this. It was definitely a requirement of the 1984 standard.



Therefore, I believe it is correct to say that ALL IEC cables should have sleeved pins on the plug tops.



I really should get a life.....
My life is far sadder.

I seem to remember that these outlets used to be BS4491. So I looked at the history, and found that it appears to have been originally published in 1967 as a draft, and published "issued" in 1969 ! (Implementing the old CEE22 standard as it was then . . .).

As I said - very sad !

-------------------------
EUR ING Graham Kenyon CEng MIET TechIOSH
G Kenyon Technology Ltd

Web-Site: www.gkenyontech.com
 31 May 2009 08:32 AM
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davyn1

Posts: 2870
Joined: 01 August 2004

i agree they should be sleeved but COD isnt specifficaly on about IEC leads(although the OP is) just the plug top itself isnt retro so you could come across an old iron (for ex) and you could'nt fail it for the plug
davy

-------------------------
just because i'm paranoid doesn't mean theyre not out to get me
 31 May 2009 02:14 PM
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Baz

Posts: 146
Joined: 24 May 2009

OK lets go back to College, the fuse is there to protect the circuit conductors, not the appliance. So for the IEC connector, it's not the rating of the connector that's important, but the rating of the lead. Yes I agree that it's a 10A connector, but is this a name rather than a rating? I can see where the confusion arises, but I would be happy to accept a moulded on IEC connector with a moulded on 13A plug with a 13A fuse (provided that the connector had the notch in the side)
 31 May 2009 02:58 PM
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perspicacious

Posts: 8055
Joined: 18 April 2006

"OK lets go back to College, the fuse is there to protect the circuit conductors, not the appliance" Baz

How the the Europeans manage without fuses in their plugs?

Non-College chaps may wish to have a read of the CoP to see what that has to say about unfused cords and appliances....

Regards

BOD

edit as smiley not working properly....
 31 May 2009 03:50 PM
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alancapon

Posts: 7492
Joined: 27 December 2005

Originally posted by: Baz
OK lets go back to College, the fuse is there to protect the circuit conductors, not the appliance. So for the IEC connector, it's not the rating of the connector that's important, but the rating of the lead. Yes I agree that it's a 10A connector, but is this a name rather than a rating? I can see where the confusion arises, but I would be happy to accept a moulded on IEC connector with a moulded on 13A plug with a 13A fuse (provided that the connector had the notch in the side)


Not convinced you have all the facts. The specification IEC60320 gives details of 12 matched plug/socket combinations. The socket on the end of what is usually referred to as an "IEC cable" or "computer cable", is actually variant C13 of this standard, and is rated for 10A. The connector you refer to has having a "notch" in it is actually the C15 or occasionally the C15A. These two connectors also have a rating of 10A each. The difference is the maximum temperature ratings. The C13 is 70 degrees Celsius, the C15 is 120 degrees Celsius and the C15A is 155 degrees Celsius. This is why a "kettle lead" which is usually a C15 can be used to power a computer, but the "computer lead" being a C13 can not be used for the kettle.


Regards,

Alan.
 03 September 2009 10:32 PM
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Angram

Posts: 657
Joined: 23 March 2009

Tim,

can I pass a .75mm lead with a 13amp fuse serving a 2kW applance?

Most users and computer suppliers have no idea that there are two
sizes of lead cable.

If there are going to be high current devices on low temperature
IEC leads; danger can arise if lead sizes become mixed surely?

I have always standardised on 1mm and 5amp fuses for personal
use and made up my own leads if necessary .

1,3,5,7,10 and 13A were available in the past.

terence
 03 September 2009 11:02 PM
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perspicacious

Posts: 8055
Joined: 18 April 2006

"1,3,5,7,10 and 13A were available in the past."

A quick look in RS will give their current (sic) availability

When the proposals for post war building studies were being carried out in early 1944, there was a proposal to have the fuses in the actual yet to be standardised new type of socket-outlet, to be wired on the proposed ring final circuit due to the likelyhood of the shortage of rubber (interestingly not Cu) after the hostilities ceased. Late in 1944 it was proposed that the manufacturers designed a new 3 kW plug (ie 13 A) with the fuse in the plug, that being either 3 A or 13 A.

Also the figure of 1000 sq ft or latterly 100 m2 for the area of a ring final circuit came from the anticipation of the standard family 3 bed semi being built with a floor area of 850 to 1000 sq ft.

Regards

BOD
 04 September 2009 09:34 AM
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gkenyon

Posts: 5354
Joined: 06 May 2002

Originally posted by: Angram

Tim,



can I pass a .75mm lead with a 13amp fuse serving a 2kW applance?



Most users and computer suppliers have no idea that there are two

sizes of lead cable.



If there are going to be high current devices on low temperature

IEC leads; danger can arise if lead sizes become mixed surely?



I have always standardised on 1mm and 5amp fuses for personal

use and made up my own leads if necessary .



1,3,5,7,10 and 13A were available in the past.



terence
There is no problem, as long as it's less than 2m.

Table 2 of BS1363-1 says that 0.75 sq mm, protected by 13A fuse, is rated at 10A (i.e. 2.3 kW), PROVIDED that it is less than 2m.

Over 2m, 1.0 sq mm must be used.

BS1363-1 should be a standard that ALL "PAT-Testers" have to hand.

-------------------------
EUR ING Graham Kenyon CEng MIET TechIOSH
G Kenyon Technology Ltd

Web-Site: www.gkenyontech.com
 06 September 2009 11:57 AM
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sparkingchip

Posts: 11682
Joined: 18 January 2003

I will stick my neck out and state the only appliances fitted with these leads, in common usage, which draw more than ten amps are a 3kw electric kettle, large kettles of the Burco "tea urn" type and steam wall paper strippers with the same elements fitted.

The kettle is intermittent usage, all new kettle automatically turn off when the water boils, so although the lead may get hot to touch it is unlikely to burst into flames.

So the only real problem would be with the Burco type heater and steam wall paper strippers drawing twelve and a half amps over a extended period,, this is indeed a problem I have witnessed on a regular basis, steam wall paper leads failing, I don't have a answer to this problem.

As these elements take the C15 connectors I would expect to see "notched leads" fitted with 13A fuses and "unnotched" fitted with no more than an 5A fuse.

The case of Tim's amplifier seems like a product not being manufactured using appropiate components, so may be a different issue.

Andy
 06 September 2009 12:03 PM
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sparkingchip

Posts: 11682
Joined: 18 January 2003

If the lead is protected by the fuse, not the appliance, should there be a fuse holder built into the amplifier if it needs a ten amp? otherwise a notched lead and 13A plugtop fuse supplys a appliance rated at less than ten amps so it is not a problem.

Andy
 06 September 2009 12:16 PM
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sparkingchip

Posts: 11682
Joined: 18 January 2003

regards the steam wall paper strippers, the 13 amp plug top tends to fail along with every thing else.

Andy
 06 September 2009 02:58 PM
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gkenyon

Posts: 5354
Joined: 06 May 2002

Originally posted by: sparkingchip
I would expect to see "notched leads" fitted with 13A fuses and "unnotched" fitted with no more than an 5A fuse.
Andy,

I don't agree, and this is based on the standards (and also on the Wikipedia page you posted to).

The C13 and C14 connectors are rated 10A too, and therefore should have a 13A fuse, if the lead is >0.75 sq mm, or if 0.75 sq mm and <= 2 m long !

The only difference between C13/14 and C15/16 is the temperature withstand (see again your Wikipedia page).

I know this also to be the case in the BS EN IEC60320-series standards, as someone asked me to check in the past - the info in the Wikipedia page seems correct (to the extent that I have checked on C13/14 and C15/16 connectors).



Just a final warning, though. I've seen some leads with moulded free socket, rating stating 6A rather than 10A. Of course, this can still be fitted with a 13A fuse, per the guidelines of BS1363-1 (as referred to from the Plugs & Sockets Regulations in the UK), but it is up to the user to ensure no "overloading".

-------------------------
EUR ING Graham Kenyon CEng MIET TechIOSH
G Kenyon Technology Ltd

Web-Site: www.gkenyontech.com
 06 September 2009 02:38 PM
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Angram

Posts: 657
Joined: 23 March 2009

Andy,

What precisely is the failure mode of the stripper leads ?

There is a miss-match here between what one would
specify and what one is entitled to fail in a PAT.

I just find this whole concept of specifying cable sizes
on intermittent overloads, in cords or ring circuits
difficult to accept in principle. Doing it on interchangeable
leads is the last straw for me.

Strippers are the camel's back then.

terence.
 06 September 2009 03:07 PM
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sparkingchip

Posts: 11682
Joined: 18 January 2003

just typing certificates and doing part p notification for a kitchen job just finished.

Whilst carrying out the work Craig the builder boarded and skimmed the ceiling, then over skimmed the walls having first striped the wall paper and tile adhesive using the steam stripper.

Part way through the stripping the stipper packed up, typical stripper from a DIY shed. The IEC connector and 13A plug top both showed signs of overheating, the IEC connector was deformed around the entry slots, the 13 A plug pins were blackened and the insulation on the pins were deformed, the flex itself appeared ok apart from nicks, cuts and scuffs. This lead was thrown away and another one out of the van used to finish the job.

I know there is the issue that these leads get plugged into a often low quality extension lead and there is a poor contact between the extension socket and plug top pins cause overheating and damage, however it is not unusual for the strippers to be used continuosly for four to ten hours at full load, I know I have done it myself, on the kitchen job Craig used his for around half a day, now the only other domestic appliance likely to run at 12.5/ 13 amps for that long is a fan heater or electric fire and normally the flex is wired straight in, a IEC lead would not be used.

We are now getting domestic dishwashers fitted with a IEC lead and fridge/ freezers, but they don't draw 3kw.

I would say with the wall paper strippers there is a mis-match and if carrying out a PAT on one the lead needs careful inspection, how you go about failing one I'm unsure as I don't think there are generally any not using a kettle lead as they have a kettle element in them, so you could find yourself banning all of them

Andy

I have seen similar damage to plug tops fitted to immersion heaters and ovens.
 06 September 2009 03:17 PM
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anastasis

Posts: 676
Joined: 01 September 2009

Andy, do you know what the rating of the steam stripper was? Presumably not more the 10A.

13A plugs do get warm if used at full load for a long time, and can overheat if the pins are tarnished or the socket contacts are loose. We've all seen this...
 06 September 2009 03:18 PM
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sparkingchip

Posts: 11682
Joined: 18 January 2003

"just find this whole concept of specifying cable sizes
on intermittent overloads, in cords or ring circuits
difficult to accept in principle. Doing it on interchangeable
leads is the last straw for me."

agreed, however if you have a extension lead with a four way adaptor on the end it will be ok with four power tools used alternatively, get four people using all four tools and you may blow a fuse, so you work on intermittent loads at times, but as you say it should not happen on the individual appliance leads.

There is only a few pieces IT equipment and the like that piggy back power supplies off another piece of equipment using IEC leads and the loads are not that large.

I have a cordless kettle in our kitchen with fixed wiring to the base, so we should not have these problems, i suspect a lot of kettles run at ten amps anyway.

Andy
 06 September 2009 04:39 PM
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sparkingchip

Posts: 11682
Joined: 18 January 2003

just looking at the link again, remember the kettle lead plug if the kettle boiled dry the connector was pushed apart by a plunger coming out of the kettle, you had to boil a pan of water on the stove then so you could have a cup of tea whilst it cooled down again so you could get the lead back in. I bet those were rated more than ten amps

Andy
 06 September 2009 04:46 PM
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sparkingchip

Posts: 11682
Joined: 18 January 2003

we are assuming that these are not some cheap counterfeit leads with statndards marks applied without any authority.


I have just pulled one out from under my desk manufactured by I-Sheng "no groove" the wiring instructions attached to the lead states use a ASTA approved 5amp fuse which is what is fitted.

Andy
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