Talk:BS 546

Photo - group shot

A group of BS 546 plugs, sockets and adaptors.

Here is a group shot of some BS 546 plugs, an inline 5A 2 pin socket and a couple of adaptors. I have more of these plugs & sockets than are shown here including some wall sockets. If anyone can think of some good photos to take for this article (angles, group shots, insides, etc.) then I can do so. Ziltro 16:23, 3 February 2006 (UTC)

BS 546

this is a very good article. A few points to add for completeness: -

Each of the three sizes - 2, 5 and 15 amp - had a 2 pin and 3 pin version. Unlike other plug systems (e.g. Australian) the 2 and 3 pin versions differed by gauge and diameter so were not compatible. I have no idea why the design deliberately ruled out compatibility - this seems pointless. The 2 and 15 amp 2 pin versions dropped out of use as a result, while the 5A version remained in use for longer, both because of its use as a shaver plug and because of the widespread availablility of adaptors (strictly speaking, these 2-pin variants probably pre-dated BS546 and were not covered by it).

The BS 1363 standard first made an appearance in 1947 and gradually replaced the BS546 types - in the UK, Ireland, most of the countries that were still ruled by the British at the time, plus a few others - e.g. Saudi Arabia (alongside the US system). India, Pakistan and South Africa were by then independent, so did not adopt BS 1363. For some reason the replacement by BS1363 was slower in Hong Kong than elsewhere. Whilst adaptors that allowed different BS546 types to mate used to be very common, those allowing mating between BS1363 and 546 were less so, other than those allowing the 5A, 2 pin size to be used in 13 A sockets.

on the subject of adaptors apparently socket doublers with 15A pins and 13A sockets are considered a rare and highly prized (and hoarded) item in the theatre lighting industry. Plugwash 23:57, 15 June 2006 (UTC)

Nice to know, I got given one recently! I shall have to photograph it. I thought they were quite common in some other country/ies though? Ziltro 04:20, 8 December 2006 (UTC)

Tone?

Someone has requested that this be cleaned up for tone. I assume the problem is particularly with the discussion of 2a 2 pin, which is indeed quite familiar. But is there anything else folks think needs improving? Bryson430 00:21, 8 December 2006 (UTC)

BS 546 2A, 5A, and 15A.

Diagrams

I eventually decided to learn SVG and measured & created these drawings. They are pretty close sizes for comparison, but are not the sizes from the regs because I don't know what they are! If anyone knows what the 'official' dimensions are then I can update these files with them. Shown looking at the socket (note titles if you view the SVG) but measured diameters are taken from the pins. Ziltro 04:20, 8 December 2006 (UTC)

• 
  2A 2P
• 5A 2P
  5A 2P
• 
  2A 3P
• 
  5A 3P
• 
  15A 3P

It should be noted that the images purporting to be 2 pin BS 546 types are no such thing. There is not, and has never been, a 2 pin BS 546 plug/socket. BS 546 deals only with earthed plugs and sockets. Mautby (talk) 14:24, 20 March 2013 (UTC)

BS socket and Europlug

In what BS socket fit an Europlug???
The 5A 2pin ?

http://en.wikipedia.org/wiki/Europlug

79.230.182.250 (talk) 23:01, 18 April 2010 (UTC)

No BS Standard socket accommodates a Europlug. However, a Europlug compatible socket is usually included in a dedicated shaver socket. Mautby (talk) 14:28, 20 March 2013 (UTC)

BC plugs

Nowhere in this category can I find any mention of British BC plugs, which were very popular up until the 1970s. Theyre not BS546, so dont belong in this article. These bayonet cap plugs fitted into bulb holders, and were how upstairs appliances such as irons, electric blankets, and heaters used to be powered. AFAIK they never conformed to any BS, and were thus effeectively banned in the early 70s.

I'd put this mention elsewhere, but there isnt really anywhere else to put it. Tabby 16:58, 29 June 2007 (UTC)

British BC plugs don't conform to any British Standard, which is why they vanished from the market place when conformance with British Standards became mandatory for all electrical accessories. It would have been up to one of the manufacturers to get them added to BS 5042 (the then standard for BC lampholders, now replaced by BS EN 61184), but presumably no manufacturer thought the cost of the effort worth what they would make in sales. BC plugs can still be found in some other countries which use BC lampholders. Occasionally they can be found for sale in the UK, but strictly it's illegal to sell them now.
81.187.162.109 20:03, 23 August 2007 (UTC)

"BC Adaptors" enabling 2 pin Europlugs to be connected to a lamp socket were also available. However BC adaptors and plugs were widely misused (overloading and the use with three wire appliances with the earth wire cut) in a dangerous manner. Does the British standard legislation make it unlawful to sell Schuko (European) or NEMA (American) plugs in the UK ? 213.40.115.69 (talk) 12:47, 8 August 2009 (UTC)

With the exception of shavers and toothbrushes, it is illegal to sell domestic appliances in the UK which are fitted with anything but a UK standard plug. Mautby (talk) 14:34, 20 March 2013 (UTC)

http://www.plugsocketmuseum.nl/SouthAfrica2.html provides an interesting read about BS 317 → BS 372 → BS 546 BC plugs and sockets, which were indeed used in the UK (and more recently in South Africa) — Preceding unsigned comment added by 78.147.197.1 (talk) 00:48, 14 December 2017 (UTC)

5 Amp BS 546 in India, Sri Lanka, Nepal, and Namibia,

In theory 15 amp plugs were proposed to be used for larger appliances (e.g. electric heaters) while smaller appliances (e.g. radios, table lamps etc) were supposed to use 5 amp. In practice this was found to be inconvenient and in many households the 15 amp plug was used for everything.

How widespread is the 5 Amp version of BS 546 in these countries ? Is the 5 Amp version always used for low current applications or is (as was the case in the UK) 15 Amp universally used for everything ? -- 80.229.222.48 (talk) 19:14, 16 November 2007 (UTC)

South Africa

The 15A 3Pin is the only current domestic wall socket standard in South Africa. In the article there is a statement about it "almost always" having a switch in countries where it is the current standard. In the case of South Africa the "almost" can be deleted as the regulations make a switch mandatory. Heavier current items such as stoves and geysers are "hard wired" into the supply with a dedicated trip-switch on the distribution board. The 5A 2Pin type is still found on older appliances but has been replaced by the Europlug in current trade and manufacture. The 5A 3Pin plug is becoming very rare and is no longer made or sold at all although many people still have adapters for them. The CEE 7/7 plug has also appeared on appliances, usually in 2pin non-polarised form. Adapters for 15A3Pin to Europlug and CEE7/7 are widely available. Roger (talk) 19:26, 25 January 2008 (UTC)

No longer made or sold at all is a very strong statement do you have evidence to back it up or are you just going on what you see in your local wholesalers or worse DIY stores? Plugwash (talk) 23:58, 25 January 2008 (UTC)

You're asking me to prove a negative? If you show me just one example of a 5A 3Pin plug or socket in a current South African manufacturer's catalog, I will withdraw my statement. Roger (talk) 06:59, 26 January 2008 (UTC)

Atlantic Lighting and Electrical Distributors in Booysens, Johannesburg stock the 5A 3Pin plug Gary van der Merwe ^(Talk) 09:39, 14 November 2008 (UTC)

Namibia

The page seems to perpetuate a theory that the 5A BS546 is the standard for this country. From where does this information derive? Pre-independence South West Africa was effectively a fifth province of South Africa and on my many visits there (in both hotels and private houses) the standard sockets were the 15A variety - I know because it fitted all of my South African gear without a problem.

I have seen this 5A "fact" presented on a few popular web sites but I have never seen any official back-up for this and I suspect that there is a fair degree of mutual self-support for this misplaced hypothesis.

Echoing Roger's comments:- in my many years in RSA I never came across a domestic 5A socket (i.e. on a standard 4x4" or 4x2" plate). I did find (and use) 5A plugs, and regularly bought 5A sockets on 2.5" circular fittings that were used with industrial conduit systems. I wired up workshop fluorecent tubes and battery back-up lighting with these. I only ever came across the 2A varieties back in the UK.

Oxonhutch (talk) 21:20, 4 February 2009 (UTC)

I'm going to do the WP:BOLD thing and remove Namibia from the "list" of countries that have 5A wall sockets - it is simply not true. All "sources" out there that say so got their info from here! Roger (talk) 16:06, 19 February 2012 (UTC)

Pin diameter

Why do the pins on a 15 Amp BS546 plug appear to have a larger diameter than those on a European Schuko plug (4.8 mm) despite the latter having a slightly higher (16 amp) current rating ? What are the official pin daimaters/spacings for the various BS546 plugs ? 213.40.115.69 (talk) 12:59, 8 August 2009 (UTC)

Someone has posted a table in the article. "15 Amp" BS546 plug have a live/neutral pin diameter of 6.9mm (Earth pins are larger) Even "5 Amp" plugs have a live/neutral pin diameter of 5.1mm (probably derived from imperial). It does seem odd that European plugs are rated for 16 Amps when their pin diameter is only 4.8mm. Maybe its because BS546 tends to use brass pins while the pins on European plugs tend to be some other material (nickel ?) although this is not always the case so can anyone else come up with a better explanation ? 86.112.87.162 (talk) 15:10, 24 December 2010 (UTC)

Although pin diameter is related to maximum current capacity, the pins on most plugs have a maximum capacity that is much larger than the nominal rating of the plug. The pins on the 15 Amp plug, for example, could easily carry 30 Amps or more. That the plug is rated for 15 Amps is purely a decision that the designer took. Compare the pin size of the IEC Connector. This has much smaller pins but can still carry up to 15 Amps (see the C13 and C15 types). 86.169.33.6 (talk) 16:40, 2 June 2012 (UTC)

15A 2 pin plug

The article makes no mention of the 15A 2 pin plug, which I'm sure was part of this standard at one time. They were widely used in older British houses before rewiring in the 1960s. I can't update the article myself as I'm unsure of their status. --80.176.142.11 (talk) 17:43, 28 September 2009 (UTC)

There is not, and has never been, a 2 pin BS 546 plug/socket. BS 546 deals only with earthed plugs and sockets. Mautby (talk) 14:36, 20 March 2013 (UTC)

Not just AC

BS 546 is an old British Standard for domestic AC power plugs and sockets. .

It was also used on DC mains systems. 213.40.128.233 (talk) 20:46, 2 November 2009 (UTC)

The cover of the 1950 edition on Scribd says AC 50/60 Hz (was there ever much 60 Hz in the UK?). Scrbid kills my computer so I didn't look at more than a couple of pages, but there was no mention of DC. --Wtshymanski (talk) 20:53, 13 September 2011 (UTC)

(What we now call) "BS 546" plugs were around long before the 1950's (they were developed in the mid-late 1920's) DC supplies were quite common back then -even after 240v/50Hz standardisation "legacy" DC systems continues in many areas for several decades. It is highly likely that BS546 plugs were used on DC supplies. The BS546 standard may not have been completly formally ratefied until 1950 but in the athmosphere of the preceeding decades (when standards would have been more piecemeal and ad-hoc) it was likely that they were used in all manner of configurations. 192.65.220.73 (talk) 14:44, 19 January 2012 (UTC)

This makes sense but it's frustrating that we can't find sources for this. The same problem exists with the NEMA connectors; for all you can tell from Wikipedia, they might as well have been raked out of the remains of a crashed flying saucer. --Wtshymanski (talk) 15:43, 19 January 2012 (UTC)

History needed

When was the first edition of BS 546 issued? What is the current edition? What were major revisions (and why?) ? Why didn't they just add fuses and shutters to BS 546 instead of coming up with BS 1363? --Wtshymanski (talk) 19:49, 4 September 2011 (UTC)

"When was the first edition of BS 546 issued?" --dunno, BSI don't seem good about presenting history on their website

"What were major revisions (and why?) ?" -- see comment above.

"Why didn't they just add fuses and shutters to BS 546 instead of coming up with BS 1363?" -- Adding fuses and shutters to an existing plug type (BTW shuttered BS546 sockets do exist as do fused BS546 plugs) does not solve the problem of preventing people connecting appliances with unfused plugs to a circuit designed for fused plugs.

"Is BS 546 still current?" (asked on BS1363 talk page). According to british standards online the core version of the standard hasn't changed since 1950 but there have been a few amendments and the standard is still current. Plugwash (talk) 20:37, 4 September 2011 (UTC)

That's unfortunate; other standards documents I have read often have a brief recitation of the editions of the standard somewhere in the preface. It makes no sense that BS 546:1950 was replaced by BS 1363:1947! There must be an older edition of BS 546. The plug museum Web site is uninformative on this point. --Wtshymanski (talk) 23:05, 4 September 2011 (UTC)

"It makes no sense that BS 546:1950 was replaced by BS 1363:1947! "

It makes perfect sense. I'm really tired of your perennial crusade to delete things just because you don't understand them. Andy Dingley (talk) 09:30, 5 September 2011 (UTC)

So you don't know either. No-one on Wikipedia ever says "I don't know". --Wtshymanski (talk) 14:06, 5 September 2011 (UTC)

Of course I know - it's very obvious to anyone familiar with the subject. I wouldn't in all honesty expect that of a Canadian, it being such a regional issue, any more than I'd be expected to understand ice hockey. However you never seem to see WP:COMPETENCE as no bar to editing blindly across any article that catches your eye, usually deleting swathes of them as you trample. Mind you, Avaya and Nortel have Canadian links now, so catalogue-list entries like Avaya IP Phone 1120 are seemingly safe from your scrutiny.

As to the dates of 546 & 1363, then why ever should the dates of the standards have to be ordered in the same order as their standard numbers?

546 existed pre-war. It was a reasonable standard for making reliable plugs on radial circuits. Low contact resistance and good terminals, with current/size-coding so as to avoid overheated sockets from excess loads. Post-war we wanted ring circuits (to save copper as a primary reason, but also then implying essential fuses in appliance plugs), and we wanted shuttering to make sockets safer. So a new standard was created, 1363 (actually 1361, 1362 & 13633), ab initio. This didn't obsolete 546 installations overnight though. 546 was still widespread until the 1970s, and I'm sure there's still some around (I bought some 2A lighting round-pin myself just weeks ago, although I don't know which standard they're to). We wanted shuttering for round pin too, hence 546:1950.

546:1950 was never replaced by 1363:1947 because 546 was never replaced by 1363. Both existed, one was a new standard that was certainly encouraged for new work and is now pretty much universal for installations. However 546 wasn't "withdrawn" in any way. The standard still exists, it still applies to round pin, where round pin is to be used. I guess (and this much I don't know) that our permitted scope for installing 546 has shrunk - you never see it as an alternative to 13A 1363 sockets and even the 2A or 5A lighting-only plugs and sockets are now a narrow speciality product. However the standard still exists. Andy Dingley (talk) 14:36, 5 September 2011 (UTC)

So when was the first edition of BS 546? It makes no sense to claim the 1950 edition was the first edition, but we have no references for earlier versions. Evidently BS 546 is not withdrawn, though it would be good to know what supplements or amendments have come out in the last 61 years.

You, too, can recommend catalog entries for deletion. --Wtshymanski (talk) 15:51, 5 September 2011 (UTC)

And isn't it kind of the *point* of an encyclopedia to teach the interested reader something about a subject? We're not just writing essays to show how clever we are; if I don't understand something in the article, maybe the article needs fixing more than I need mocking. --Wtshymanski (talk) 15:57, 5 September 2011 (UTC)

Scribd has a pirated copy of a 1982 print of BS 546, but Scribd makes my computer slow to a crawl - I couldn't look at more than the first two pages, but it interestingly says something about sockets for both 50 and 60 Hz. No DC mentioned, at least not on the first two pages. --Wtshymanski (talk) 20:45, 6 September 2011 (UTC)

Is there any authority for a pre-1950 edition of BS 546? Or was this a de-facto standard that never got formalized until after the war? Anyone? The standard numbers are suggestive, but not definitive. --Wtshymanski (talk) 21:38, 14 September 2011 (UTC)

The standard has been around (in the de-facto sense) has been around since the late 1920's but may not have been formalised until 1950 (pre-WW2 a lot of industry standards in Britain -to the extent that they existed at all seem to have been very ad-hoc and informal). The current wording of the artile isint very clear on this. It gives the iimpression that BS546 has only been around since 1950 (although prior to that it may have been called something else). — Preceding unsigned comment added by 192.65.220.74 (talk) 10:14, 14 February 2012 (UTC)

Ive done some edits in an effore to dispel the confusion somewhat although Im conscious this stuff still needs citations. I have tried finding suitable sources on the net to add but another user seems bent on wasting my time by engaging in four minute revert wars and I really have better stuff for doing. 84.13.206.199 (talk) 20:03, 17 February 2012 (UTC)

It a bit awkward coming up with a good wording for this article. An accurate (if somewhat pedantic) assesesment of the situation would be that its nonsense to speak of any use/existance of "BS546" sockets prior to 1950 seeing as how there was no BS546 standard before then. On the other hand These plug and sockets were the defacto standard (or more accurately set of standards) since the late 1920's and seem to have been in existance for well over a decade before that. So to state without qualification that BS546 came into existance in 1950 while strictly speaking is an accurate statement is nevertheless somewhat misleading. The difficulty is componded by the fact that coming up with acceptable sources on a rather obscure subject like the origins of an old and largely obsolete (at least in its country of origin) standard for electric sockets only ever used in a handful of countries is somewhat challenging. 192.65.220.74 (talk) 10:24, 21 February 2012 (UTC)

It would be highly desirable to find some old wiring manual or something that says that BS546 is a standardization of the <foo> connector that was used back before the Great War. We can't say that BS546 was used before 1950 because we have no evidence that there was an edition of the BS546 standard before 1950. We might say that a connector resembling what was later to be come the BS46 standard was available, but there's no references. (Some of the back numbers of "The Electrician" are on the Web, and even some issues of "New Scientist" talk about such mundane matters.) It's confusing to this reader anyway that the obsolescent BS546 has a first standard date that is years more recent than the BS1363 standard that succeeded it; of course, there may have been other priorities than electrical standards publications in those years. --Wtshymanski (talk) 14:27, 21 February 2012 (UTC)

My knowledge of British culture has now allowed me to work out how the plugs got standardized 30 years before the standard was published. --Wtshymanski (talk) 15:04, 21 February 2012 (UTC)

This is not so uncommon and is not limited to Britain either. The idea of 'standards' for everything is a relatively new concept. In the case of BS546, the standard was drawn up in the 1950's (or possibly a little earlier) but was based on three designs of plug and sockets that had already existed for several decades. Prior to this time a national standard defining the parameters of the plugs was presumably not considered necessary, though doubtless there were manufacturing drawings that specified the important parameters. I dare say the US NEMA standards for their plugs were probably developed in a similar manner. It might suprise you to learn that BS1363 was also drawn up after the plug and socket system was designed. There were a number of competing designs for the 13 Amp plug system for the UK after the war. Three reached prominence, but the design settled on was the MK design and BS1363 was written around that design of plug after the desision was made.

Standards came in mostly because of the increasing focus of safety. Years ago, I owned a 16mm projector, which had an easily removeable cover over the lamp. Just inside the cover was a large resistor, the top (and accesible) connection of which was at live mains (the resistor dropped the supply to power the 120 volt projector bulb). This projector was sold in the 1930's as a child's toy!! Had there been any standards at the time, it would almost certainly never have been sold. And in case anyone tries to suggest that such a lethal toy would never have been sold in the US, I should point out that it was of US manufacture. The resistor allowed it to be sold worldwide. 86.169.33.6 (talk) 17:02, 2 June 2012 (UTC)

The history of BS 546 can be traced back to BS 317 published in 1928, its official title was "Hand-Shield and Side Entry Pattern Three-Pin Wall Plugs and Sockets (Two Pin and Earth Type). BS 317 was superseded in 1930 by BS 372 "Side-Entry Wall Plugs and Sockets for Domestic Purposes" Part II. Note 1 of Part II states that there are only minor alterations from BS 317. BS 372 specifies 2A, 5A, 15A and 30A plugs and sockets, the 2 pin versions are in Part I and the 3 pin versions are in Part II. BS 372 Part II was itself superseded in April 1934 by BS 546 which included the same 4 plug/socket sizes with the same dimensions. (Appendix A of BS 546-1934 allows for the optional inclusion of fuses up to 5A in any version, except the 2A plug, limited to 2A.) The current version is still BS 546-1950, but with various amendments up to Amendment 8 dated 15th May 1999. Note, BS 546 has only ever included 3 pin plugs and sockets. Deucharman (talk) 19:36, 14 June 2012 (UTC)

Thanks for digging all that up, this entirely resolves my anxieties on these two standards. Formal citations to the various editions of the standards would be a help. --Wtshymanski (talk) 14:26, 23 August 2012 (UTC)

I note that there still seems to be some confusion over the history of the BS 546 type plugs, and there is a paragraph in the history section of the article which is inaccurate and inadequately referenced.

Starting with the direct history of the standard, as Deucharman has noted above, BS 546 traces its history back to (at least) BS 317 published in 1928. Between 1930 and 1934 the (then current) BS 372 had two parts, one covering 2 pin types and one covering 3 pin types, but that does not seem like a good reason for subsequently assuming a particular connection between the two (differently sized) types.

The paragraph in question starts with the claim: Prior to the adoption of (what was to become) BS 546 as a standard, there were around two dozen different types of power socket used in different cities throughout Britain. This may be true, but it is unsourced, and more importantly the introduction of BS 546 did not put an end to the multiplicity of 3 pin types in use in the UK. The 3 pin Wylex type was introduced in 1926, and (according to AC power plugs and sockets) was still in use until the 1980s. The Dorman Smith type continued in use through the 1950s.

The paragraph goes on to state: The development of the National Grid in the late 1920s provided the impetus for greater standardisation of voltages, frequencies and plug types. This is supported by a reference to a TV programme, but does that count as a reliable source? What was actually established in 1926 was a co-ordinating body called the Central Electricity Board, the National Grid itself dates to 1938. It is reasonable to ask why the development of the National Grid operating at 132 kV would influence the type of sockets used at 240 V!

An addition to the paragraph has recently been added stating: In parts of Britain (two pin) plugs similar to those defined by the original BS 372 Part I standard had been in use since as early as 1911. In fact we know that the first 2 pin plugs used in Britain (and probably the world) date back to 1893, and by 1889 there were two pin plugs in the GEC catalogue. BS 73:1915 is the original standard for 5 amp 2 pin plugs and sockets, superseded by BS 372.

The correct place for old British 2 pin plug information is probably AC power plugs and sockets in a new sub-section under "Obsolete Types", and I propose to start that. Based on the poor quality and inappropriateness of the current paragraph in BS 546 I am going to delete it entirely. Mautby (talk) 14:19, 20 March 2013 (UTC)

Dont agree with your "inaccurate and irrelevant" assesment. A paragraph in the history section of an article outlining how BS546 (and its predecessors) evolved and had its roots is hardly irrelevent surely ? As for inaccuracies surely its better to point out and/or correct such inaccuracies than wholesale deletion of paragraphs ? As for the two dozen types of connector surely this is sourced albeit from a TV programme. Dont see why a TV programme should be regarded as less relaible than a print article ? 192.65.220.46 (talk) 14:45, 20 March 2013 (UTC)

There is still history there, but it is relevant and accurate history! The unsourced "two dozen types" claim had been there since 1st November 2009, and was not discussed in the TV program originally broadcast in 2010. The TV citation was for the claim that the National grid was the impetus for standardization of sockets, clearly an unsupportable idea that was not part of that programme. The origins of BS 546 predate the grid, and BS 546 was not the only type of earthed socket in use prior to the introduction of BS 1363. Mautby (talk) 16:32, 21 March 2013 (UTC)

BS 372

Since we now have an idea of where the two pin plugs came from (BS 372 Part I) maybe we should now restore them to this article and make BS 372 a redirect to this article? After all since BS 372 Part II was the three pin plugs and sockets of BS 546, I can't see giving BS 372 an article of its own. Carolina wren (talk) 01:00, 14 December 2012 (UTC)

Because BS 546 replaced BS 372 part II does not seem a very good reason for assuming a connection between BS 546 and BS 372 Part I. We know that the two parts originated in different earlier BS standards, and that there is not a commonality between the dimension of the 2 pin plugs in Part I and the 3 pin plugs in Part II. If anyone has access to BS 372 and can provide real information then a separate article might be justifiable. Mautby (talk) 19:09, 21 December 2012 (UTC)

They are both standards for British round pin plugs, and they overlap by describing the same plugs in at least some cases. Perhaps it would need to be renamed to British round pin plugs and sockets with the various current and obsolete standards being redirects to the relevant sections. Carolina wren (talk) 05:56, 23 December 2012 (UTC)

An anon asks "Does BS372 merit an article of its own ?". I, for one, would love to read a comprehensive overview article about the evolution of plug statndards in the UK (or anywhere), but I don't think an article on BS372 would pass the WP:N hurdle. --Wtshymanski (talk) 14:05, 20 March 2013 (UTC)

See "History needed" section above. Mautby (talk) 14:39, 20 March 2013 (UTC)

2A plug in UK universtiies

In some UK universities (certainly into the mid-eighties), 2A BS546 sockets were fitted in student accommodation in order to limit students power usage. Suitable fused (2A) plugs were sold in campus shops; students were expected to be able to change the plugs on their appliances. Many students bought 13A multiple-socket extension leads and changed the plug on those instead. There was also something of a black market in 3A and 5A fuses compatible with the 2A plugs. — Preceding unsigned comment added by 87.161.253.150 (talk) 18:55, 31 December 2012 (UTC)

I've also heard similar stories but I don't have any sources to back them up. Afaict fused 2A plugs are still made by MK though they are expensive and tricky to find. Afaict all BS546 fused plugs use BS646 fuses so there is nothing stopping someone fitting a 5A fuse to a 2A plug.

Yes, the fuse type must be BS 646, I've added that to the article. As far as fitting the wrong fuse, the same thing applies to BS 1363, there is nothing to stop a user fitting a 13 amp fuse to a cord set rated at 3 amp, but it would be illegal to supply it that way. Mautby (talk) 14:20, 21 March 2013 (UTC)

Regarding the plug-top type to which you refer here, I'm currently writing a book on electrical matters, so I'd like to query what you have here - since it's at variance with my information. Firstly, the Universities that I have used, all used solely the simple so-called 'BS546' 2-amp UNFUSED variety of plug-top in their halls of residence. However, since you go into detail regarding fuses, you must have experienced something different. You seem to be alluding to the so-called BS646 type of plug-top - that took a BS646 fuse, but otherwise resembled the standard BS546 variety. However, as far as I'm aware, that particular variety existed solely in a FIVE AMP style (but would accept 1, 2, 3, or 5-amp fuses); those are still available from Crabtree - at exorbitant prices; there were never any 2-amp or 15-amp styles of fused plug-top ever made - as far as I can ascertain; am I wrong there? Logic suggests that there ought to have been - but I've never heard tell of any; I posess 2x the 5-amp variety. Another reason for me to query what you have said, is that there'd be no need to fiddle about getting replacement fuses (such were & are available readily) because the 'standard' pattern of 2-amp, 5-amp, and 15-amp plug-top non-fused types were and are readily available; my local branch of B & Q currently stock them! The wall-sockets for the BS646 system are one and the same as used with BS546 plug-tops, so the cheap expedient would be to get the BS546 plug-top - despite the fact that that would contravene the supposed requirements of the system - I'm sure that students just wouldn't bother to concern themselves over that; those 2 or 5-amp plug-tops & related wiring would easily bear 10-amps - if not a lot more if on a 'ring' circuit, as the fusing suggests. This make me wonder if in fact you are alluding to the 'Wylex' plug-top, that was not readily obtainable (except in Manchester); those were obtainable both fused and non-fused in 2, 5, & 15-amp versions (the fuses used were the standard BS646 ones). They were also available as 13-amp fittings (with BS1362 fuses), and a degree of interchangeavility was permitted between all three 'systems'. Those 'Wylex' fittings are very distinctive, since they have a large 'round' earthing pin (2-amp fitting had slightly 'flattened-off' sides to prevent use with larger plug-tops), and broad flat load-bearing pins - so very distinguihable from the run-of-the-mill fittings. Schools etc. commonly also used the fittings for low-voltage D.C. in laboratories - so as to be 'different'. As far as I'm aware, there is strictly-limited usage still continuing, but fittings have to be specially made in quantities of 1,000 pieces or more; they are used to try to discourage 'unauthorised' connections. Would you please clarify the position - and indicate possible sources of information. Thanks JohnIGoodwin@Yahoo.co.uk — Preceding unsigned comment added by 86.176.144.80 (talk) 13:03, 24 September 2013 (UTC)

First an observation, the original post in this section was from someone who is anonymous and whose post was autosigned, the second post is, according to the history, by Plugwash, but there is no signature at all - it looks as though the WP system has mangled this? The third post, confirming Plugwash's suggestion that fuses fitted to BS 546 plugs are to BS 546 is by Mautby. This is a discussion on the article, but the article itself does not mention use in Universities, and as there are no references cited then it should not. Then we have an enquirer who is asking WP editors to assist them with writing a book? I cannot add anything to what may or may not have been the practice in some UK universities, but I can make some unequivocal statements about BS 546 and BS 646. The article correctly states that Plugs fitted with BS 646 fuses have been optional since the original BS 546:1934 with maximum fuse ratings of 2A in the 2A plug, and 5A in the 5A, 15A and 30A plugs. The enquirer refers to "the so-called BS646 type of plug-top - that took a BS646 fuse, but otherwise resembled the standard BS546 variety" but that is a figment of the enquirer's imagination, BS 646 is a standard for fuses, not plugs! The MK catalogue still includes both unfused and fused BS 546 plugs, the model numbers for fused types are as follows: 639 WHI (2A fused), 641 WHI (5A fused), 643 WHI (15A fitted with 5A fuse). There may be other sources for fused BS 546 plugs, but I am not aware of any at present. Deucharman (talk) 14:22, 24 September 2013 (UTC)

BS 372 or earlier standards and decimalization

It's fairly evident from the values in the dimensions table that they are all binary fractions which have converted to thousandths of an inch and rounded down in the conversion. Does anyone have access to the older standards so as to document when dimensions such as ⁷⁵/₁₂₈ in became 0.585 in? Carolina wren (talk) 19:29, 2 October 2013 (UTC)

Carolina wren, I see where you are coming from, but you are making assumptions which WP does not permit. Let me give you some examples, if you look at the oldest BS for plugs and sockets, BS 73 (1915) you will find that the original dimensions are given in different forms depending on the type of dimension. Some examples: pin diameter and pin spacing are given in decimal fractions for both imperial and metric units, but pin length is given in vulgar fractions for imperial and decimal fractions for metric. So, the original imperial definition of a 5 A two pin plug pin spacing is 0.656 inch, the diameter 0.199 to 0.201 inch, and the length 5/8 inch. You simply cannot make assumptions as to the effects of rounding if a dimension has never been stated as a vulgar fraction. The only dimension which may be stated in WP is that given in the standard, not what you assume may be its derivation. For that reason I am reverting your comment in the main article as it is misleading. It is also unnecessary as editors who wish to modify factual data should not do so on the basis of assumption. Long obsolete standards can be quite difficult to track down, BSI do of course have them, but will charge you big fees, £100 plus for each photocopy of a standard. Alternatively you may use the BSI library for a fee of £20/hour for non-members. The IET archive is NOT a source for old standards, so the best solution is to use a major reference library such as the British Library or the National Library of Scotland. Access to current standards, and some previous versions, is available free via many public libraries using the BSOL online system. Deucharman (talk) 21:12, 2 October 2013 (UTC)

Even if you feel that the embedded comment was inaccurate as the reasoning of how the current decimal values came to be, I think a comment (either hidden as I had it so that only an editor would see it, or in the visible text) emphasizing that the decimal inch values given in the table are exactly as the standard has them is in order. Otherwise, there will be people trying to make future "helpful" edits in the future to "correct" the rounding from round to down to the commonly taught round to near. While you said "It is also unnecessary as editors who wish to modify factual data should not do so on the basis of assumption.", the sad fact is they will. Without additional info, those values simply look too much like "wrongly" rounded numbers, and hence people will try to "correct" them, as has already happened. Some of that help will occur after both of us have ceased editing Wikipedia, as we inevitably will some day (unless the afterlife gets a Wi-Fi hotspot by then), so simply reverting that error when it occurs is not an optimal solution. Taking preventative measures is what is needed. Carolina wren (talk) 21:35, 2 October 2013 (UTC)

I hope my addition fits the need? Deucharman (talk) 21:56, 2 October 2013 (UTC)

Quite adequately. I think it would be interesting to include information in the History section on the evolution of the tolerances and when changes from binary fraction to decimals occurred, but that is a low priority need, and could even be saved for when, if ever, we get articles on those precursor standards. Carolina wren (talk) 00:35, 4 October 2013 (UTC)

Proposal to create new detailed group articles about AC power plugs and sockets
Request for comments

A proposal has been made by Jeh to redefine the present AC power plugs and sockets article, and its related detailed articles, of which this is one. The proposal can be found at Move all detail info to group-specific articles?

In an attempt to move this forward I have prepared a draft of one of the articles suggested in the proposal: "AC power plugs and sockets - British and related types". This combines the British related elements of the AC power plugs and sockets article with the full BS 1363 and BS 546 articles. The draft can be found in my sandbox: User:Deucharman/sandbox. Please do not edit my sandbox, but make all comments and suggestions at Move all detail info to group-specific articles?. I have also placed a request for comments on the BS 1363 page. Deucharman (talk) 16:47, 27 December 2013 (UTC)