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Appliance Ratings and 13A plug tops

statter
Hello

I looked last year for portable heating and not surprisingly there was little above 2.5kW rating.  All the old 3kW stuff has long gone.

I was surprised however to find a wide range of steam irons rated at 3000W and even 3100W.  (that's almost 13.5A at 230V).  I realise of course that irons are likely to be much more intermittent than heating and that 13.5A is very unlikely to blow a 13A fuse but it cant be good practice to overload plug/ socket like this.  A decent ironing session can still be hours ……   OFC at 240v its under 13A but 230v has been the standard for ages now.   In my experience many socket/ plug combinations are marginal approaching their rating so deliberate overloading will only make matters worse over time.  I would have thought that these appliances wouldn't qualify for CE marking and couldn't be sold legally?  Does anyone know if there is a BS or EN for small appliances?


Thanks


Peter
  • 0
    The test methods for 13A plugs and sockets are discussed in the old forum here

    It was really in the context of electric car charging, but I think the general conclusion was that a 13A plug and socket are fine for 13A, in short bursts, but the steady state rating is a bit hit and miss - and the BS test method of clamping to the pins to test the plugs in isolation, and using test plugs to test the sockets may not catch all cases of contacts being not really well enough cooled to avoid the onset of heat induced oxidation and then thermal run-away.


    Real plugs  do not remain polished like new, and for good reasons no-one sticks little wire brushes into their sockets to burnish the contacts (*), so once things get a bit browned off, it is likely to go down hill irreversibly.


    * Actually I did see an advert for such a thing for the CEE form sockets once, looking like a small bottle brush but with brass bristle, more like a suede shoe brush, and it struck me as a contender for some sort of  "most dangerous product of the year" award. For such things sockets have shutters.


    I'm not sure how well the old 15A round pin plugs  fare on a 16A breaker, but the larger contact area must help.



  • 0

    davezawadi:

    I used to have an MK safetyplug on my 180A stick welder, perhaps a 10 kW appliance with a solid fuse fitted. It never overheated despite some fairly heavy and extended use. Products today are just plain useless, but made to BS EN standards of course. 




    Though plugs are not made to a BS EN standard. They are made to a pure BS which has not been approved by a majority (for which read 'compromised') at CENELEC.

    Alasdair

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    Chris Pearson:

    This plug (with bottom, sides, and top) was on a 3 kW heater. I suspect that the over-heating may have been in part due to inadequate insertion leading to arcing. I cannot see why the pins would run so much hotter than the cable.

     



    The problem with 13A plugs is that they have a built-in heating element, in the form of a BS1362 fuse.  At currents that would cause any other design of plug to get a bit warm, the fuse in a BS1363 plug can produce a significant amount of heat, which is then trapped inside a well-insulated enclosure.
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    Simon Barker:




    Chris Pearson:

    This plug (with bottom, sides, and top) was on a 3 kW heater. I suspect that the over-heating may have been in part due to inadequate insertion leading to arcing. I cannot see why the pins would run so much hotter than the cable.

     



    The problem with 13A plugs is that they have a built-in heating element, in the form of a BS1362 fuse.  At currents that would cause any other design of plug to get a bit warm, the fuse in a BS1363 plug can produce a significant amount of heat, which is then trapped inside a well-insulated enclosure. 


    Yes, but in this case, the fuse receptacle is undamaged.

  • 0

    davezawadi:

    Interesting that both pins got very hot (well probably over 70C). I wonder what the pins are made of, perhaps high resistance material. Brass is expensive now! I don't see much sign of arcing on the pins, they usually get discoloured and pitted if this happens. Did the socket survive the onslaught?




    There is discolouration which is consistent with arcing just where the chamfers on the live pins begin. It can be seen on the N pin in the photo.


    My thinking is that the load would heat the pins to let's say 50 deg C and a little arcing would take it over the safe level. So careless insertion or may be tripping over the flex may have been enough. Alternatively, with the contacts gripping poorly, might there have been a resistive element to the overheating?


    I don't know which socket was in use at the time, but none shows any sign of damage. They are all good old MK.


    P.S. no I am not going to fit AFDDs. ?

  • 0
    3kW immersion heaters are still on sale. No doubt that some are plugged into 13A sockets.

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