13A plugs will not carry 13A !

[JohnW2]

I would think there are quite a lot of immersion heaters wrongly connected by a plug.

I'm sure there are. Indeed, I don't even know if it has always been regarded as 'wrong'.

However, the duty cycle of the average immersion heater is not all that high, so I don't think it qualifies as a protracted 13A load.

As I said before, the only 'plugged in' domestic equipment I can think of which is likely to draw sustained high current for several hours or more is a heater (partricularly if it has no thermostat) - and that's usually going to be nearer 2kW than 3kW.

Kind Regards, John.

 

[davelx]

Perhap someone who has access to the BS 1363 document could look up/summarise exactly what the current rating spec/test entails?

 

[JohnW2]

Perhap someone who has access to the BS 1363 document could look up/summarise exactly what the current rating spec/test entails?

Although primarily about dounle sockets, this extensive thread may be of some assistance, in particular:

...and....

[I took this:


The test current shall be passed through the plug
and through a load connected to the flexible cord for
a minimum continuous period of 4 h, or longer until
stability is reached with a maximum of 8 h, stability
being taken as less than1 K rise within 1 h. The
temperature rise is calculated by deducting the
reference point temperature from the measurement
point temperatures recorded (see Figure 17 and
Figure 17(a) respectively).

Table 4 — Permitted temperature rises

[code:1]Measurement point Temperature
rise

K

Line plug pin spacer (see Figure 17) 35

Neutral plug pin spacer 35
(see Figure 17)

Terminals or terminations 45
(fixed accessories only)

Terminals or terminations (portable 50
accessories only)

Accessible external surface 50[/code:1]

to mean that if the temperature had not stabilised it would fail the test.

Kind Regards, John.

 

[DetlefSchmitz]

At a quick glance the temperature rise test for a plug involves a single socket in a wooden cabinet, and a current of 14A for at least 4 hours or up to 8 if stability isn't reached.

The permitted temperature rise for terminals or external surfaces is 52°K.

Draw your own conclusions...

 

[JohnW2]

At a quick glance the temperature rise test for a plug involves a single socket in a wooden cabinet, and a current of 14A for at least 4 hours or up to 8 if stability isn't reached. The permitted temperature rise for terminals or external surfaces is 52°K. Draw your own conclusions...

Indeed (but where does your 52°K come from; the material I posted seems to say 50°K ? ). Since I continue to assume that at least the more reputable of manufacturers ensure that their products pass this test, a few points:

• 1...The test seems a bit deficient, in that it appears to allow one to stop (and take the temperature figure) at 8 hours, even if the temperature is still rising at more than 1°K per hour at that time. Although one would imagine that temperature stability normally would have been achieved long before then, it seems odd to have a potentially 'uncompleted' test like that in a standard.
  
  2...Many/most of the reports of plug damage we hear of relate to very protracted high loading. A temperature rise of 50°K could easily mean a maintained stable temperature of 75°C or more, and one imagines that might well do damage if sustained for 12h, 24h or whatever (and the test may well have stopped at 4h) - not the least the annealing of fuse contacts which has already been mentioned, which could lead to subsequent overheating.
  
  3...These tests are presumably undertaken on pristine new products. One imagines that once there is some grime, oxidation or whatever on the scene, temperature rises could easily be greater.

Kind Regards, John.

 

[DetlefSchmitz]

Sorry, I was summarizing from the standard itself, from the section relating to plugs rather than sockets.

And yes the impression is of a series of tests on a new plug with pass criteria. The tests don't really relate to real-life usage, and of course don't guarantee behaviour over protracted periods.

The most relevant test may be the aging test. The plug is heated under certain conditions for 1 week, and then examined to see whether there is any degradation likely to cause it not to pass any other test. Mmm.

 

[JohnW2]

Sorry, I was summarizing from the standard itself, from the section relating to plugs rather than sockets.

Ah, OK - but there doesn't seem any material difference apart from the fact that the plug is allowed to get 2° hotter than the socket - that makes sense, I suppose, since one can only test a plug-socket combination!

Kind Regards, John

 

[DetlefSchmitz]

Sorry, I added to my post.

It seems to me from memory that the permitted temperature rise makes it hotter than BS7671 allows touchable items to get.


Ed: No it's probably just inside.

 

[JohnW2]

And yes the impression is of a series of tests on a new plug with pass criteria. The tests don't really relate to real-life usage, and of course don't guarantee behaviour over protracted periods.

Quite.

The most relevant test may be the aging test. The plug is heated under certain conditions for 1 week, and then examined to see whether there is any degradation likely to cause it not to pass any other test. Mmm.

As you say, Hmmm - that sounds also rather subjective, unless it's much better defined that you have indicated.

Kind Regards, John.

 

[JohnW2]

It seems to me from memory that the permitted temperature rise makes it hotter than BS7671 allows touchable items to get. Ed: No it's probably just inside.

Hmmmm. Whatever BS7671 may say, there's no way you're going to get me touching anything which is 50 degrees above ambient - that's seriously hot!! 14A for 4 hours isn't that far beyond credibility for real world use, so I'm a bit surprised that the Standard allows a plug/socket to get that hot under such use.

Kind Regards, John.

 

[DetlefSchmitz]

As you say, Hmmm - that sounds also rather subjective, unless it's much better defined that you have indicated.

Judge for yourself:

Untitled

• DetlefSchmitz
• 19 Oct 2011
• 1

 

[JohnW2]

As you say, Hmmm - that sounds also rather subjective, unless it's much better defined that you have indicated.

Judge for yourself:...

You seem to have 'indicated' all that there is to indicate

It's really a bit ridiculous for it to say "...following which they are examined and shall show no damage which: - would lead to non-compliance with this standard..." - since the only way one could know the answer to that would be to repeat all the other tests and, if that's what it means, it should say so!

Kind Regards, John.