Double sockets

[mikhailfaradayski]

If you are an electrician tasked with installing these devices, Which do you feel is the most relevant standard to work to BS1363 or BS7671:2008?

BS7671 is of course the standard for installations. It requires socket-outlets for a.c. to comply with BS1363, with a few exceptions listed in 533.1.5.

Are they in agreement with each other, or do they contradict each other?

Neither. They do however complement each other.

Ah, maybe i should have been more specific here. Ill try again-

From both standards, with respect to the definition of what a socket outlet is (including the possibility of a single device containing the facility for more than one plug to be connected at the same time), do they agree or disagree?

If you were in a customer house, having just installed one of these devices, and then this question is asked, how would you choose to respond to the customer?

I wouldn't be in that situation, not being an electrician. However if someone were to ask the question (what was it again?)

err, let me look back a few pages

I would reply along the lines that a dual 13A socket-outlet, whatever the make, may reach an uncomfortable temperature if two 13A loads are connected to it for a long period.

About the same as me, and then i might just finish your sentence by adding "so I would advise against doing so"
Safe advice, not confusing to the customer, everyones happy, home in time for tea

 

[stillp]

with respect to the definition of what a socket outlet is (including the possibility of a single device containing the facility for more than one plug to be connected at the same time)

Ah, but the definition of a socket-outlet is clear, although less so in BS7671, and it does not include the facility for more than one plug to be connected at the same time. 1363 is clear that the term refers to the "set of three", and 7671 states "intended to receive a plug". Not "one or more plugs, but "a plug".

About the same as me, and then i might just finish your sentence by adding "so I would advise against doing so"
Safe advice, not confusing to the customer, everyones happy, home in time for tea

Glad we agree.

 

[JohnW2]

I don't really understand how you can disagree with the first statement. In terms of safety-related issues, it is probably the rule, rather than the exception that 'safety margins' are built in to standards - i.e. that products have to pass tests undertaken at conditions more severe than those for which the product is 'rated'

With hindsight, you're probably right that tests are often more arduous that the parameter being verified. Not always though.
Tests less severe than the rating are quite common, for example when testing at the full rating would be dangerous or destructive. The committee has to judge how severe a test is necessary to verify that the requirements of the standard are met.

I'm not sure that I really agree with that, although a lot is dependent upon one's views on the meanings of 'often' and 'common'. 'Type testing' is not infrequently destructive, as are sample tests as a part of production QC. If you weighed 90 kg and had to be suspended over a long drop by a rope, would you be happy to use a rope that had been tested at 90kg (or even, by analogy with what you say, 70 kg), inevitably ± testing errors and manufacturing tolerances - or would you perhaps be happier withy a rope that had been testsed at, say, 150kg, or ideally which had been type- and sample- tested to destruction in order to determine it's breaking strength?

I think that you (John) and I are in agreement, that the rating of each "set of three" is 13A, regardless of how many are attached to a mounting plate. They are likely though to overheat if a multiple socket-outlet has all outlets loaded to the full rated current - a situation that the standard does not consider to be normal.

Yes, I think we do agree on all that, but on the basis of common sense. I strongly suspect that you would not get (m)any manufacturers to say that their multiple sockets were 'rated' at 13A 'per set of three', and nor do I think that a lot of electricians, here or elsewhere, would necessarily agree with us. After all, it is they (many of them) who have so often said that that double sockets ("except MK ones") are 'rated' at 20A total.

Kind Regards, John

 

[mikhailfaradayski]

with respect to the definition of what a socket outlet is (including the possibility of a single device containing the facility for more than one plug to be connected at the same time)

Ah, but the definition of a socket-outlet is clear, although less so in BS7671, and it does not include the facility for more than one plug to be connected at the same time.

I would disagree with that. The definition in chapter 2 does not exclude the possibility of connecting more than one plug. Furthermore, the pictoral representation of a 'BS1363 socket outlet' contained in app15 clearly shows twin sockets, but still refers to them in the singular. If 1363 says only 1 set of female contacts, then7671 shows a single 1363 device, but it has two sets of contacts, surely thats not complimenting each other and there is a contradication

1363 is clear that the term refers to the "set of three", and 7671 states "intended to receive a plug". Not "one or more plugs, but "a plug".

indeed, it says 'a plug' not 'one plug', its says 'female contacts' but does not specify how many contacts are permitted

About the same as me, and then i might just finish your sentence by adding "so I would advise against doing so"
Safe advice, not confusing to the customer, everyones happy, home in time for tea

Glad we agree.

lol, i'm not sure how long we have been agreeing for? The whole time or just most of the time?

The only part i disagree with is that 'its confusing' when its clearly straight forward and unambiguous

TBH i can't quite believe this thread has gone 6 pages so far

 

[Robgers]

"Never before in the field of household sockets has so much been written by so many for so few"


Winston O'Boogie wrote that I believe.

A fake fiver for identifying Winston.

 

[mikhailfaradayski]

Hi John,

Can you name and shame those who talk about '20A 13A sockets' as i know i have never said that and i'm not sure its safe to say 'many say that...' when it may just be down to the repetitive ramblings of just one rum soaked idiot who owns a set of wire cutters.
Please don't tar us all with the same brush!!

 

[JohnW2]

If you were in a customer house, having just installed one of these devices, and then this question is asked, how would you choose to respond to the customer?

I wouldn't be in that situation, not being an electrician. However if someone were to ask the question (what was it again?) I would reply along the lines that a dual 13A socket-outlet, whatever the make, may reach an uncomfortable temperature if two 13A loads are connected to it for a long period.

.
I wouldn't be in that situation, either, for the same reason stillp gave, but if I were asked the question, I would give the same answer as him/her, probably supplemented by the "...and I would therefore advise against it" bit. However, my concern would be that the customer would almost certainly not ask the question, since virtually all of them would believe (I would personally say, not unreasonably) that two 'full' 13A loads was perfectly OK.

Imagine that a set of car tyres were 'rated' for use at 80 mph. Would you expect a driver to ask whether that meant that driving continuously for 4 hours at 80mph was OK, or expect that the truth was that testing had only been done for 3 hours (since more than that was considered 'not usual') and that >3 hours might well be dangerous?

Kind Regards, John.

 

[mikhailfaradayski]

"Never before in the field of household sockets has so much been written by so many for so few"


Winston O'Boogie wrote that I believe.

A fake fiver for identifying Winston.

maybe we could introduce a sub topic about the boolean logic for mowing the lawn, that should keep this going for a few more pages yet....

BTW, wasn't it Winston P. O'Boogie?

Fake fiver sent to you in the fake post, fake 1st class

 

[JohnW2]

Hi John, Can you name and shame those who talk about '20A 13A sockets' as i know i have never said that and i'm not sure its safe to say 'many say that...' when it may just be down to the repetitive ramblings of just one rum soaked idiot who owns a set of wire cutters. Please don't tar us all with the same brush!!

I'm certainly not going to point fingers, but if you do a search (here or in other forums), you will find that some of the most seemingly authorititive contributors have 'pointed' out that 'double sockets are only rated for a total load of 20A' on many occasions. Were that not the case, I would not even have started this thread. Maybe some of them would be prepared to 'shop themselves'?

Kind Regards, John.

 

[JohnW2]

Hi John, If you thought this subject was complicated and confusing, take a look at this question:-
//www.diynot.com/forums/viewtopic.php?t=265550
Its gonna mash your melon

Well, it's far too short a thread to mash any of my melons - but I thought the whole subject of diversity was invented by publicans who wanted to profit out of the endless hours of debate in the bars that it would generate

Kind Regards, John.

 

[mikhailfaradayski]

If you were in a customer house, having just installed one of these devices, and then this question is asked, how would you choose to respond to the customer?

I wouldn't be in that situation, not being an electrician. However if someone were to ask the question (what was it again?) I would reply along the lines that a dual 13A socket-outlet, whatever the make, may reach an uncomfortable temperature if two 13A loads are connected to it for a long period.

.
I wouldn't be in that situation, either, for the same reason stillp gave

so what is it you do?

, but if I were asked the question, I would give the same answer as him/her, probably supplemented by the "...and I would therefore advise against it" bit. However, my concern would be that the customer would almost certainly not ask the question,

sorry John, but thats nothing more than conjecture

since virtually all of them would believe

ditto

(I would personally say, not unreasonably) that two 'full' 13A loads was perfectly OK.

again, you seem to be taking your personal view point and then suggesting that lots and lots of people think the same way. I disagree with this.

Imagine that a set of car tyres were 'rated' for use at 80 mph. Would you expect a driver to ask whether that meant that driving continuously for 4 hours at 80mph was OK, or expect that the truth was that testing had only been done for 3 hours (since more than that was considered 'not usual') and that >3 hours might well be dangerous?

If they were rated at 80 mph, then driving at 80mph should be safe to do indefinitely.

However, employing you rationale, if the same driver had the same tyres at the same rating, but also knew that part of the testing of those tyres was that they were tested for 3 hours at 120mph, and he then asked 'how long can i safely travel at 120mph for? what would your response be?

can you name and shame the culprits who refer to the '20A 13A sockets?

(BTW, i take it that you know that the size of the fuel tank on a Bugatti Veyron is considered as a safety feature in respect to the tyres?)

 

[mikhailfaradayski]

Hi John, Can you name and shame those who talk about '20A 13A sockets' as i know i have never said that and i'm not sure its safe to say 'many say that...' when it may just be down to the repetitive ramblings of just one rum soaked idiot who owns a set of wire cutters. Please don't tar us all with the same brush!!

I'm certainly not going to point fingers, but if you do a search (here or in other forums), you will find that some of the most seemingly authorititive contributors have 'pointed' out that 'double sockets are only rated for a total load of 20A' on many occasions. Were that not the case, I would not even have started this thread. Maybe some of them would be prepared to 'shop themselves'?

Kind Regards, John.

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

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, if the problem were as endemic as you report, then im sure someone would have put down the rum bottle for long enough to give us an insight into their thoughts

 

[ban-all-sheds]

Commission Regulation (EC) No 2257/94:

http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31994R2257:EN:HTML[/QUOTE]
And what does that say?

 

[JohnW2]

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'

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

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. BAS strikes me as someone who can look after himself, 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)

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; 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.

 

[ban-all-sheds]

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.

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, 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 also know that when I googled for "All MK socket-outlets are manufactured to comply with BS1363 part 2: 1995 and are rated at 13A per unit" I couldn't find anything except it being endlessly recycled around forums like this one.