Double sockets

[holmslaw]

..

 

[mikhailfaradayski]

Go on, stick yr neck out and substantiate your claim that 'most electricans believe that.... 20A blah, blah etc...

Ah – a subscriber to the fashionable ‘blame culture’ who needs 'named culprits'

no, not at all, i was merely trying to get you to substantiate your claim of 'many/most/lots/majority of electricians....believe in 20A 13A sockets. (I do get the feeling that you like to employ quite a bit of conjecture in your POV with the intention of making your POV a fact of 'how it is' and i think that is unfair if you won't back up your beliefs.) Since you weren't specific about who made those claims, but did seem to intimate that this belief was widespread. The actual wording of this is a point of pedantry, but the sentiment seemed quite clear.

Well, for a start, you have cunningly changed my 'many electricians' to 'most electricians'!

not intended to be manipulative, just a word change since i didn't scan back to ensure it was verbatim.

That aside, identifying the culprits has proved far more tedious than I had expected, because this forum's search facility is less sophisticated that I had hoped - it seems that in only searches within thread titles.

thats why i declined to go randomly searching in the dark, as per your invitation, to attempt to find something which you claim exists, but won't produce the facts yourself, when i don't agree that such evidence is in abundance anyway. Surely it would be appropriate for you to show the evidence, not for me to go find it....

I believe that the belief in the existence of '20A 13A sockets' is far from widespread amongst electricians. Nobody has jumped into this thread to suggest or support this POV....

I agree that no-one has said it explicitly in this thread.

i would go further and suggest that the number of folk who claim '13A sockets are rated at 20A' would be in single figures at worst.

BAS strikes me as someone who can look after himself,

I think he has a care support team to help him sometimes, perhaps twice a day for washing and cleaning?

so I'm not too hesitant to point out the he got very close early in the thread:

MK twin sockets are only rated to 13A total.

No - they would not be compliant with BS 1363 if that were the case.
(and then added a paste from BS1363 indicating the 20A testing condition for double sockets, but without further comment)

admittedly, i overlooked that, but to be fair, when i see sheddy's name and lots of cut/paste adjacent to it, i often scan past it as it is usually just lots of offensive comments toward someone or other.

I’m sure that he (I’m assuming it’s a he!)

I don't think sheddy is comfortable with being pidgeon-holed like that

will speak for himself, but I presume he was trying to suggest that the rating was not ‘13A total’ but 20A total;

Ah, I see. That would suggest that there is even less credibility to your 'most/many/lots of electricians believe...' thing. It would seem that sheddy stands alone in this belief, but he is not an electrician!

I can’t think of any other interpretation. Whatever, he certainly was saying that RF Lighting’s ‘rating = 13A total’ was wrong.

So, you now have to rely on BAS's honesty to tell us what he would have answered if, at the time he wrote that message, he had been asked to state what he believed was the 'rating' of a double socket.

Kind Regard, John.

You'd have to ask him, as I think he still claims to have been ignoring me for the past six months or so...

 

[JohnW2]

I believe that to be compliant with BS 1363 a DSO has to be rated at 20A - the test is carried out with the socket mounted inside a closed wooden box with the current flowing for at least 4 hours, and no more than 8 hours, by which time the temperatures of various parts of the socket must have become stable and must not exceed certain values.

Many thanks for clarifying your view. Per earlier discussions, I think that this illustrates the reason for many of the confusions. In order for a double socket to be compliant with BS1363, it has to pass the temperature rise test (at 20A) you mention, but that does not mean that the product then has to be 'rated' at 20A. I think that these different 'understandings' of what is meant my 'rating'/'rated' is probably the basis of most of the apparent disagreements we've seen in this thread (and elsewhere).

How that time period and requirement to cope with 20A squares with "Research by ourselves and third party organisations has shown that all MK double sockets can safely withstand a continuous load of 19.5A for an indefinite period. Increasing the load slightly will begin to cause heat and mechanical stresses on the components in a relatively short period" I don't know,....

If the information we have is all still current, I can but presume that the statement squares with the reported test results because a very small increase from 19.5A to 20A does not result in the product failing the BS1363 test - since it clearly is claiming compliance to that standard.

.... but I do know I can't find that statement on the MK website, or in either my electronic or paper MK catalogues. True they are not the latest, but they post-date April 2004.

I didn't know it had been quoted that early in the IET forum. As I said, the post I was quoting from (which seems virtually identical to the earlier one you found) was posted on 2nd December 2009, namely December 2009. Unless you are missing it, it sounds as if that statement may have disappeared from more recent editions of the MK catalogue.

Kind Regards, John

 

[JohnW2]

I’m sure that he (I’m assuming it’s a he!) will speak for himself, but I presume he was trying to suggest that the rating was not ‘13A total’ but 20A total;

Ah, I see. That would suggest that there is even less credibility to your 'most/many/lots of electricians believe...' thing. It would seem that sheddy stands alone in this belief, but he is not an electrician!

Not at all. As I said, searching for the other assertions about a 20A 'rating' (which were the reasons I started the thread) is too tedious in this forum - that one instance from BAS was easy to find, since it's in this thread! If I stumble across any of the others, I'll let you know, but I'm not going to spend ages hunting for them.

Kind Regards, John.

 

[stillp]

I believe that to be compliant with BS 1363 a DSO has to be rated at 20A - the test is carried out with the socket mounted inside a closed wooden box with the current flowing for at least 4 hours, and no more than 8 hours, by which time the temperatures of various parts of the socket must have become stable and must not exceed certain values.

Not quite correct BAS, the socket-outlet is mounted on a metal back box that is set into a wooden block. The front face of the socket-outlet will therefore be in free air, although the standard doesn't say so.
The test is continued for at least 4 hours or until a stable temperature is reached, with a maximum of 8 hours, so the temperature could still be increasing after 8 hours.

Some of the other test conditions are interesting (to me and my fellow standards anoraks, at least).
A single socket-outlet is connected to an incoming cable and an outgoing cable. A twin or multiple is connected to an incoming cable only. Does that imply that the standard writers thought that twin socket-outlets would not be used in ring final circuits?
2.5 mm sq is used for single and twin, but 4mm for "more than two sets of socket contacts".

 

[mikhailfaradayski]

I’m sure that he (I’m assuming it’s a he!) will speak for himself, but I presume he was trying to suggest that the rating was not ‘13A total’ but 20A total;

Ah, I see. That would suggest that there is even less credibility to your 'most/many/lots of electricians believe...' thing. It would seem that sheddy stands alone in this belief, but he is not an electrician!

Not at all. As I said, searching for the other assertions about a 20A 'rating' (which were the reasons I started the thread) is too tedious in this forum - that one instance from BAS was easy to find, since it's in this thread! If I stumble across any of the others, I'll let you know, but I'm not going to spend ages hunting for them.

Kind Regards, John.

No worries, I understand the tedious act of searching this forum, but if you ever do stumble across any more supporters of the '20A 13A socket' thing, it would be nice to see their thoughts.
Until such time, i'll respectfully maintain the belief that you are really focusing so closely on something that you can't see the wood for the trees, generating a storm in a teacup based on your inflated view that most/many electricians are confused about the subject, when they are not as it is quite a simple concept to grasp.

Its been nice chatting, but since sheddy seems to be involved again and someone is questioning his dictat, i expect this thread to be locked soon.

Regards

Mik

 

[ban-all-sheds]

Many thanks for clarifying your view. Per earlier discussions, I think that this illustrates the reason for many of the confusions. In order for a double socket to be compliant with BS1363, it has to pass the temperature rise test (at 20A) you mention, but that does not mean that the product then has to be 'rated' at 20A. I think that these different 'understandings' of what is meant my 'rating'/'rated' is probably the basis of most of the apparent disagreements we've seen in this thread (and elsewhere).

Well - apologies for any additional confusion - I guess I should have said "I believe that to be compliant with BS 1363 a DSO has to be rated at at least 20A....."

 

[ban-all-sheds]

Not quite correct BAS, the socket-outlet is mounted on a metal back box that is set into a wooden block.

Again apologies for lack of precision - the socket itself is mounted in a metal back box - what I meant was that the whole assembly being tested is enclosed in a wooden box.

The front face of the socket-outlet will therefore be in free air, although the standard doesn't say so.

No it doesn't, and you'd have to have (IMO) an odd definition of "free air" because (unless they've changed it - I've got the 1984 version), the description says

"The incoming cable and outgoing flexible cord shall
enter the test cabinet through holes in the top
surface which shall then be sealed to prevent
circulation of air."

and in Figure 17(a) — Apparatus for temperature rise test which specifies the dimensions, materials and finish of the box, and the position of the socket under test and the thermocouple reference point, it says "One wall to be removable to provide access."

To my mind, specifying that implies that the front is not open, and saying that cable entry points are to be sealed to prevent circulation of air indicates that the intention is that the socket under test shall not be in free air.

The test is continued for at least 4 hours or until a stable temperature is reached, with a maximum of 8 hours, so the temperature could still be increasing after 8 hours.

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.

That would be consistent with the purpose of the test, whereas allowing a socket to carry on getting hotter and hotter after 8 hours would make a mockery of it.

 

[JohnW2]

Well - apologies for any additional confusion - I guess I should have said "I believe that to be compliant with BS 1363 a DSO has to be rated at at least 20A....."

I fear that doesn't really help the confusion but, rather, perpetutes the notion that BS1363 in some way dictates the 'rating' of a product.

Passing the specified tests is necessary in order to achieve compliance with the Standard. However, the 'rating' is something which is decided by the manufacturer, and will often be different (in one or other direction) from the test conditions required for compliance with the Standard.

Imagine that a company manufactures some new-fangled double socket which was easily able to sustain 2x13A loads indefinitely without overheating. If it also 'passed' all the other tests specified in BS1363, that product would most certainly be compliant - but there is no reason why they could not 'rate' it at 26A. Equally, if it were an ultra-cautious compnay, there is no reason why they could not 'rate' it at 13A, or even 10A, if they felt that was appropriate. It would remain compliant with BS1363 with any of those 'ratings'.

Kind Regards, John.

 

[ban-all-sheds]

I take your point.

But MI's can't cancel BS requirements - if I had such a socket from Cautious Electrical Accessories plc, and I ran 20A through it and it suffered damage, CEA would not get away with saying "but we only rate it for 10A" when they've also said that it complies with BS 1363:1995.

 

[JohnW2]

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 snipped]

to mean that if the temperature had not stabilised it would fail the test.
That would be consistent with the purpose of the test, whereas allowing a socket to carry on getting hotter and hotter after 8 hours would make a mockery of it.

Again, frighteningly imprecise language for a Standard, but I am inclined to agree that your interpretation is probably what was intenbded.

My father, who was a Standards Engineer in ther aeronautical industry, will be undoubtedly be turning in his grave at some of the potentially ambiguous wording of these Standards!

Kind Regards, John.

 

[stillp]

BAS, I suspect the standard has changed somewhat since your 1984 edition. There is no Figure 17a in the 1995 edition of Part 2. There is a box as you describe illustated in BS 1363 Part 1, but that is the standard for plugs, not socket-outlets. There are some references to cable lengths "within the enclosure" which, since no other enclosure is specified, must mean the back box.
The only reference I can find in Part 2 to sealing of entry and exit points is "Where possible, the cable shall enter and leave the enclosure through the standard knockouts provided and these, if required, shall be fitted with suitable grommets. The points of entry and exit shall be sealed to prevent circulation of air".

Regarding the test duration, "with a maximum duration of 8h" means exactly what it says, regardless of whether the temperature has stabilised.

Do you have a view on why only one cable is used for the test of a dual socket-outlet?

 

[ban-all-sheds]

BAS, I suspect the standard has changed somewhat since your 1984 edition. There is no Figure 17a in the 1995 edition of Part 2. There is a box as you describe illustated in BS 1363 Part 1, but that is the standard for plugs, not socket-outlets. There are some references to cable lengths "within the enclosure" which, since no other enclosure is specified, must mean the back box.

So :1995 says that the temperature rise test shall be carried out inside a test cabinet but does not describe how that cabinet is to be constructed or used?

The only reference I can find in Part 2 to sealing of entry and exit points is "Where possible, the cable shall enter and leave the enclosure through the standard knockouts provided and these, if required, shall be fitted with suitable grommets. The points of entry and exit shall be sealed to prevent circulation of air".

The terms "standard knockouts" and "grommets" indicate with a high degree of certainty that they're talking about the socket backbox, not the test cabinet.

Regarding the test duration, "with a maximum duration of 8h" means exactly what it says, regardless of whether the temperature has stabilised.

How does the actual text differ from the 1984 version? Does it no longer refer to the temperature stabilising at all?

Do you have a view on why only one cable is used for the test of a dual socket-outlet?

None whatsoever.

 

[JohnW2]

I take your point.
But MI's can't cancel BS requirements - if I had such a socket from Cautious Electrical Accessories plc, and I ran 20A through it and it suffered damage, CEA would not get away with saying "but we only rate it for 10A" when they've also said that it complies with BS 1363:1995.

The only thing CEA could not get away with would be claiming BS1363 compliance for a product that did not pass the tests specified by that standard.

However, a manufacturer is free to make whatever recommendations ('ratings') they may wish, regardless of any Standard. If, for example, it is their view that, despite being able to pass a BS1363 temp-rise test (over 4-8h), it is inadvisable to use their product for 20A (partiocularly continuously), they are perfectly free to make that recommendation ('rating') - and I personally suspect that would be a good defence against any claim relating to damage resulting from long-term use at 20A, regardless of the BS compliance.

Of course, if the socket suffered damage at 20A in less than 8 hours, then that could bring into question whether the product really was BS1363 compliant, which is a different matter. However, I think BS1363 only refers to tests on spanking new products. It is very possible that a product which passes the temp-rise test when new would fail that test (within 8 hours) after it had been on someones kitchen wall for 20 years (and that may well be why many/most manufacturers appear to choose to 'rate' double sockets at 13A total, despite the 20A BS1363 test) - so even early overheating at 20A does not necessarily provide evidence of non-compliance.

Kind Regards, John

 

[JohnW2]

Regarding the test duration, "with a maximum duration of 8h" means exactly what it says, regardless of whether the temperature has stabilised.

I think the wording is far more ambiguous than you seem to believe - and, as I've said, on the basis of common sense I'm more inclined to go with BAS's interpretation of what was intended - although it's basically anyone's guess.

Kind Regards, John