ECN Forum

History of the Australian plug

Posted By: aussie240

History of the Australian plug - 07/24/05 01:07 AM

I mentioned in another thread I had the details of where our plug & socket configuration came from. I've since OCR'ed the article which was printed in "Australian Amateur Radio Action" vol 9, issue 12 (March 1987). Here it is:

"Unless they've been overseas, or stayed in an international-standard hotel, the majority of Australians probably take the ordinary 3-pin electricity mains plug and socket for granted. But anyone who has encountered the various non-interchangeable types of 2-pin and 3-pin plugs and sockets in use in Europe, the UK and the USA will be aware of Australia's good fortune in having a standard design throughout the country.
Shortly after World War 2, in about 1949, the UK adopted a 13A parallel flat pin design which incorporates a fuse in the plug, but Australia had adopted its standard long before this. Tracing its history, however, was more difficult than I had expected and involved me in some correspondence.
My first letter, to the Energy Authority of New South Wales, produced the information that "existing Authority records do not include the history of the origin of the standard three-pin, flat pin plug and plug socket. Plug and plug sockets used in this country comply with the requirements of Australian Standard AS-3 112-1981 'Approval and Test Specification for Plugs and Plug Sockets'as published by the Standards Association of Australia. This standard was first published in 1937 as AS-Cl 12 and the Standards Association of Australia may have a copy of the original issue plus each subsequent revised edition in its library at Standards House, 80 Arthur Street, North Sydney 2060.
'A measure of control over the sale of certain 'prescribed' and 'proclaimed' electrical articles and fittings, including plugs and plug sockets, has been exercised in New South Wales since 1938. The initial scheme in 1938 operated under the provisions of the Local Government Act 1919 and the present scheme operates under the provisions of the Electricity Development Act 1945.
"Plugs and plug sockets are 'prescribed articles' pursuant to the Electricity Development Act 1945 and, as
such, may not be sold, hired or exposed or advertised for sale or hire unless they have been approved by the Authority or the approving authority in another State and are marked with the allotted approvals marking. Similar legislation applies on each Australian State or Territory
"The approval marking takes the form of a letter identifying the State of origin approval, eg 'N' for NSW, 'V' for Victoria, 'Q' for Queensland, etc, followed by a number allotted by the approving authority) identifying the person or company to who the approval was granted."
The Standards Association of Australia told me that the background information on the origin of the three pin, flat pin plug and plug socket was rather sketchy due to the time elapsed since its initial adoption. However, they supplied the following'.
"(a) The majority of the work would appear to have been carried out in Victoria by SECV with the help of Australian manufacturers.
"(b) The design is virtually identical to a pre-existing American configuration except that the pins are 2 mm to 3 mm longer.
"(c) The configuration was first published as an Australian standard in 1937 as AS-C 112. The current edition of this standard is AS-3 112-1981.
"(d) The current configuration also covers 15 amp and 20 amp 3-pin flat pin configurations. Again, Australia is in the fortunate position as the system was designed so that any plug will fit a plug socket with the same or a higher current rating but not the reverse.
"(e) This system is also used in New Zealand, Fiji and New Guinea, and to some extent in Argentina."
The State Electricity Commission of Victoria was rather tardy in replying to my letter, but a follow-up phone call produced the following:
"Archival records and minutes of meetings dating back to 1927 have been reviewed as staff have had the opportunity to do so and, although some references were noted of comments on the three-pin flat pin plug system, there are no specific comments on the origin of same.
"Inquiries have been made of former Electrical Approvals Board members and other long-serving personnel, but to date no specific information has been unearthed. At the present time we are following two lines of inquiry with retired personnel, but as one has been on extended holidays we have not been able to get in contact with him."
The SECV also made the suggestion that "one possible line of inquiry which may be fruitful may be Mr K Gerard of Gerard Industries (Clipsal) in South Australia as that firm has manufactured three-pin plugs and sockets for many years, possibly over 50 years."
And it was here that I struck gold. Mr Gerard was prompt in his reply and I cannot do better than quote directly from his letter to me:
Prior to World War 1 and during 1914-18, various plugs and sockets were imported from England and used in Australia.
During the early 1920s, it was difficult to import English plugs because of the shortage in production and at the same time it was noticed that a various assortment of plugs was being used in Australia and these plugs had round pins.
"Some American plugs, sockets and cord extension sockets were imported and these were of the flat pin type, ie 2-pin flat pin plug with the pins parallel and the 3-pin flat pin plug which had the configuration of the present 3-pin plug. Late in the 1920s, Ring Grip Ltd of Victoria and Gerard lndustries Pty Ltd (Clipsal) made 3-pin accessories to interchange with the US design.
"As Australia was committed to the 'earthing' system of supply, it was realised that a 3-pin plug was required.
"About 1934 a meeting was called by the SEC V, who was the leading supply authority in those days, at which a representative of the SECV, Standards Association, Mr Tivey from General Electric, Mr Fred Cook from Ring Grip, and Mr Geoff Gerard (my brother) from Clipsal were present. General Electric were importing their own 3-pin plug, etc, from the USA at that time. "The meeting, after reviewing all the plugs (English and American) being imported into Australia, decided to adopt the American 3-pin flat pin plug as an Australian Standard. The manufacturers' representatives considered flat pins were easier to make and their installation machines at the time were capable of making flat pins better then round pins.
"In adopting the USA configuration, the pins of the Australian design were shortened by 3 mm in length because of better safety standards against 'wrongful' insertion into sockets that were then produced and also to lessen the probability of personal contact with the pins when inserting plug into socket.
"A standard plug gauge was suggested, being similar to the one used by Clipsal in their plant, and this was submitted to the Standards Association of Australia and was finally published in a Standard Specification AS-Cl 12 for plugs and sockets in 1937.
This was adopted by all State supply
authorities and hence this 3-pin plug manufactured in Australia by Ring Grip and Clipsal became an Australian Standard.
"The design of 3-pin plugs has had a number of changes over the years since then, but the configuration of the pins has remained the same. People who travel to the USA, UK and Europe realise how fortunate we are to have a standard plug and socket throughout Australia."
I am indebted to those who went to considerable trouble researching on my behalf for supplying me with the information used in the preparation of this article."
Posted By: C-H

Re: History of the Australian plug - 07/24/05 02:59 PM

Very interesting reading! Yes, I know, I'm an extreme geek!

I wonder if the original American plug was intended mainly for Line (120V) + Line (120V) + Neutral, thus making it a 240V plug?

It seems most plug designs were fixed by ca 1960.

The Schuko existed, so did the American and the South African (old British) plugs.

I think the standard for the Swiss plug is from 1959, making it somewhat newer. Of course, this could simply be an update of an older standard. The Israeli plug is also rather new.

Don't know how old the French, Italian and Danish plugs are, but hardly any younger.
Posted By: aussie240

Re: History of the Australian plug - 07/25/05 01:56 AM

"I wonder if the original American plug was intended mainly for Line (120V) + Line (120V) + Neutral, thus making it a 240V plug?"

I've been wondering the same thing...if an Australian appliance was plugged into the equivalent 3 pin socket in the US, would the casing be connected to earth or neutral? Is it used for a straight single phase 240V supply with earth, or is it a 120V two phase supply with neutral on the 3rd pin? The appliance would obviously work either way, but I'd feel safer if the case was connected to earth and not neutral. The US method of wiring appears to use something like our M.E.N system so the neutral and earth would be at virtually the same potential.
Posted By: pauluk

Re: History of the Australian plug - 07/25/05 12:03 PM

Quote
Very interesting reading! Yes, I know, I'm an extreme geek!


Aren't we all at ECN? [Linked Image]

This does indeed make for interesting reading.

The "Crowfoot" receptacle has cropped up every so often in threads before, so I did a little searching. Here's what our own Bjarney had to say about it in this thread :

Quote
similar to what in the US used be called - in slang - a 'crowfoot' device - for its shape. Both were rated 125/250V 3-wire, non-grounding, but the grounded-neutral pin was improperly used as an equipment-ground connection.


Just to complicate things further though, take a look at the receptacle from this thread :

[Linked Image]

It's clearly designed to take either a "crowfoot" plug or an NEMA 1-15 type (but not a 5-15), yet the flat blade is clearly labeled as as ground, not a neutral.

Paging Bjarney....... [Linked Image]


Quote
The US method of wiring appears to use something like our M.E.N system so the neutral and earth would be at virtually the same potential.


Yes, the American system is equivalent to your MEN or the British PME arrangement. In fact at the main panel there can be a single neutral/ground busbar, bonded to the case and to which both the incoming supply neutral and the grounding electrode are connected. At sub distribution panels though, neutral and ground are kept distinct and separate.

There are still many American installations in which the dryer and range use a 3-wire connection (using the 10-30 and 10-50 receptacles), and the appliance frame is grounded to the neutral. This was allowed only where the circuit was fed directly from the main panel. If the circuit came from a sub-panel, then the 4-wire hookup was needed so that the ground was completely separate.

New installations now have to use the 4-wire system exclusively.
Posted By: classicsat

Re: History of the Australian plug - 08/03/05 03:01 PM

Around our farm, we used to have the crows foot recepticles, instead of the normal 5-15 type, and were wired similar to how a 5-15 would, one of the anlged slots to line, the other to the grounded conductor, the middle verical slot to earth.
Posted By: IanR

Re: History of the Australian plug - 08/03/05 06:13 PM

I seem to remember reading somewhere here that these crowfoot 120V receptacles were some of the, if not the first grounding devices here in the states. It predates the NEMA 5-15, actually it predates NEMA. When a device needed to be grounded it used this crowfoot instead of the 1-15, simply because the 5-15 didn't exist yet. Later, after introduction of the 5-15(ok well after!)the crowfoot configuration was designated 10-20

[This message has been edited by IanR (edited 08-03-2005).]
Posted By: yaktx

Re: History of the Australian plug - 01/04/06 05:43 AM

The 1947 NEC Handbook mentions a requirement for at least one receptacle in the laundry area to be a three-wire type, with the third wire reserved for equipment grounding. There is no elaboration on the type of receptacle required.

The 1951 Handbook has the same requirement, but has an illustration of a duplex receptacle and plug of the configuration that we now know as NEMA 5-15. I believe it can be safely assumed that this configuration (now standard throughout North America) dates to 1950 or 1951.

I recently did some work on a 1950 house which had a porcelain Hubbell twist-lock receptacle in the laundry room. I am sure this was installed to meet the 1947 Code requirement. I am 99.9% sure it has never been used!

American sparkies who are familiar with the NEMA straight-blade chart frequently mistake the NEMA 10-20 for the Aussie/NZ configuration, but this is incorrect. The pix Paul posted on this thread are of a different USA standard, one dropped before the NEMA chart was created. Like most T-slots, it is rated 125V 15A/ 250V 10A (probably the origin of the Aussie 10A standard), whereas the 10-20 has wider-spaced pins and is rated 250V 20A.

I still see 10-20 receptacles on occasion. Here in Texas, they were used for window air conditioners in the '50s. If the house was upgraded to central A/C, the window unit receptacle was no longer needed, and therefore was never upgraded to later standards.

BTW, Woodhead still makes a line of devices in the 10/15A non-NEMA configuration that more or less matches the Aussie/NZ standard.

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Posted By: pauluk

Re: History of the Australian plug - 01/04/06 11:13 AM

On the subject of the T-slot receptacles (meaning the old style with both sides a T-slot, not just one as with 5-20 and 6-20 NEMA types), I've wondered how and why these came into being.

If both 120 and 240V appliances could be wired with either parallel or tandem plugs at one time, it seems like it could have been a disaster waiting to happen for someone.
Posted By: Texas_Ranger

Re: History of the Australian plug - 01/05/06 01:18 AM

Quote
I think the standard for the Swiss plug is from 1959, making it somewhat newer. Of course, this could simply be an update of an older standard.

Well, it has clearly evolved from the old ungrounded system that has once been used all over Europe, 4mm round pins on 19mm centers.
Germany seems to be the only country that ever had ungrounded plugs with 4.8mm pins rated 10A. Austria simply never had any ungrounded plugs rated for more than 6A.
Posted By: yaktx

Re: History of the Australian plug - 01/05/06 05:06 AM

Quote
If both 120 and 240V appliances could be wired with either parallel or tandem plugs at one time, it seems like it could have been a disaster waiting to happen for someone.


This continues to cause confusion to the present generation of electricians.

The parallel vs. tandem issue should be considered separate from the 125 vs. 250 issue. In the early days, the medium Edison base was the only universal wiring device standard in the USA (and only after 1900, as the Thomson-Houston and Sawyer-Mann bases were also common before that). Several companies in the first two decades of the century produced two-piece "cap and base" plugs in different competing configurations. The most common of these were the parallel and the tandem. By 1936 (actually probably by the late '20s) the parallel device was most common, yet there were still enough tandems around to make T-slots a good idea.

The voltage issue is quite another matter. Several Electrical Nostalgia posts question the reason for a 10A 250V rating. Prior to about 1920 (I'm not exactly sure when, or which antique book I read this in, although they are all on my shelf), lighting circuits were to be fused at 10A. Originally, I think they were limited to 6A, as the medium Edison base was very early on limited to 660W. After about 1920, lighting circuits were allowed to be fused at 15A, as that is the actual ampacity of 14 AWG (2.08mm2) rubber wire. I guess the 250V rating was frozen at 10A since these devices were probably never used much at 250V.

I should mention that in those days there was no really strict rule limiting a particular receptacle configuration to a particular voltage. I gather that 32VDC farm installations used the exact same wiring devices as 120VAC installations at the time (I know for certain they used medium Edison-base devices). I've also heard that 120VDC installations in major cities used the same receptacles as AC installations elsewhere.

I have a variety of old devices here in a box:

Hubbell tandem Edison plug base, rated 300V 3A.

"C-H" (Cutler-Hammer?) "loop-prong" cap and base rated 660W 250V.

GE T-slot receptacles, one a single and the other a duplex, rated 10A 250V.

Porcelain Paulding T-slot duplex receptacle, rated 15A 125V and 10A 250V.

Arrow-Hart duplex T-slot (which I removed from the 1890s house where I lived in college), 15A 125V and 10A 250V.

I think that the tandem configuration was thought of as just another 120V configuration.
Posted By: yaktx

Re: History of the Australian plug - 01/05/06 05:24 AM

I quote from Sec. 1991 of the 1951 NEC Handbook, comments:

Quote
Figure 28 shows a duplex receptacle and an attachment plug intended for use where it is desired to provide for grounding the frames of small portable appliances. These devices are rated 15 amp, 125 volts. The receptacle will receive standard two-pole plugs, so grounding is optional with the user. The grounding contacts in the receptacle are electrically connected to the supporting yoke so that the connection to ground is automatically provided if a metal-enclosed type of wiring is used. (italics mine)


I assume the earlier crowfoot receptacles (like today's NEMA 10 devices) did not have the "ground" contact bonded to the yoke.

The comment continues:

Quote
For use on circuits of voltages higher than 125 volts, a duplex receptacle and attachment plug has been developed which is exactly the same as the design shown in Fig. 28, except that the current-carrying blades of the plug and contacts of the receptacle have the tandem arrangement instead of being parallel. These devices are rated 15 amp, 250 volts. It is expected that a change will be made in the Underwriter's Laboratories' Standard to require a rating of 250 volts only for 10-amp attachment plugs and receptacles of the tandem type. This will make it possible to ensure compliance with subparagraph 1 of section 2111 where attachment-plug receptacles of the grounding type or other type are installed on circuits having voltages higher than 150 volts between conductors. (italics mine0


The editor, Arthur Abbott, and his successor, Frank Stetka, were still waiting as of 1959 for this UL change to take place. I don't know when it finally happened, as my '62 and '65 books are not Handbooks. It was a non-issue by '68 (and of course forgotten today).

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Posted By: SvenNYC

Re: History of the Australian plug - 01/05/06 04:50 PM

Quote
Germany seems to be the only country that ever had ungrounded plugs with 4.8mm pins rated 10A.


Isn't that what we call the "contour plug" in here?

Quote
Austria simply never had any ungrounded plugs rated for more than 6A.


So what about appliances with those contour plugs? I guess they're not sold like that over there?
Posted By: Lostazhell

Re: History of the Australian plug - 01/05/06 07:33 PM

I'm assuming these were the precursor to the T-slot... I've found these oddities in turn of the century houses and buildings... this one shows a sole rating of 10A 250V

[Linked Image]


Then there's the T-Slot/Aussie combo I found in a 1920's liquor store.. Made by Hubbell

[Linked Image]


On the back it doesn't mention anything about grounding like the combo unit PaulUK posted above... It just shows "2 wire terminals" and "3 wire terminals"

[Linked Image]
Posted By: yaktx

Re: History of the Australian plug - 01/06/06 01:36 AM

Randy,

Is there continuity between the vertical pole of the crowfoot and the mounting strap?

I've never seen one of these referred to as a "grounding" receptacle in old catalogs and textbooks. They are always described as "3-wire polarized", but they seem to have been used the way we use a NEMA 5-15 today. How was this one wired when you took it out?

About 90% of housing stock in my area is postwar, so I don't see as much of this kind of stuff. I have been hunting for a receptacle like the one in the first photo, which does look functionally equivalent to a T-slot. (The parallel slots don't appear to be polarized.)

The crowfoot shown does appear to have about the same blade spacing as the 1-15, and we already know that a 1-15 plug can be mangled to fit an Aussie receptacle, so this must be the parent pattern. (Of course, this may be a later iteration.)

Interesting that we had this pattern way back in the '20s, and we could have gone with it and had grounding receptacles from the beginning, as Australia and New Zealand have. But no, we had to wait 40 more years, and now, forty years after that, there are still millions of buildings out there with ungrounded receptacles. Oh well, more work for us, right? [Linked Image]
Posted By: yaktx

Re: History of the Australian plug - 01/06/06 05:19 AM

Oh, Randy, another thing:

How do you manage to find 70+ year-old devices that aren't covered in 50 coats of paint? [Linked Image]
Posted By: Lostazhell

Re: History of the Australian plug - 01/06/06 05:48 AM

yaktx,
Regarding the crows foot outlet, there's no continuity to the mounting yoke from the vertical pole, The way the outlet was wired was a little different, and I'm not sure if it was acceptable at the time or not... The T-slot outlet was wired typical, but the crowfoot outlet was wired 240V between the angled blades and the neutral from the T-slot looped up and over to the vertical blade of the crowfoot... I took it out and replaced it with a Nema 5-20 duplex and split it for 2 dedicated ckts.

The outlet in the first pic is from a house built in 1900 in Compton, CA.. It's the only duplex of it's style I've ever seen (So of course I had to recommend it be replaced [Linked Image] )There isn't any polarity to it, although it's worn to the point that a polarized plug will insert into it. I have a few of the single style ones from the same house and a couple others built in 1898 and 1903 (I got some snazzy pushbutton switches from those houses also [Linked Image] )
Just for the sake of it, I tweaked an old 2 prong plug with a pair of needle nose a little bit and it fit into the crowfoot plug just as if it was made for it, showing the blade spacing is close, if not exactly the same.

It is interesting to think of having grounded outlets waaaaay back in the day, but compared with our modern NEMA 5-15, 5-20, etc... there is one thing of signifigance, and thats the fact of the ground pin being longer than the current carrying blades... Ensuring that the plug has grounding contact made before making energized contact.. (Now if we could make some foolproof way of keeping 5-15's from being installed without a ground wire [Linked Image] )
Yeah, we still have millions of homes lit with knob and tube, and other ungrounded systems.. "More work for us..." Job security [Linked Image] [Linked Image]

Randy

PS... the outlet on the top didhave 50 coats of paint on it... 2 words, "Goof Off" [Linked Image]
Posted By: Trumpy

Re: History of the Australian plug - 01/06/06 07:15 AM

Folks,
Not looking to detract from the very good Original post by Aussie, but this was mentioned in a recent Break-In magazine (Amateur Radio magazine).
I will type it out verbatim so that there is no confusion if I try and "edit" it.
Quote
The article in the ------- issue of Break-in about insulated pin mains plugs is correct but there is another issue with "our" mains plug, which has surfaced in the last year or so:

Several major regions in China use a mains plug having the same "foot-print" as the Australia/New Zealand plug.
However, they are made to a different standard which requires the pins of the plug to be 1mm longer than ours; this extra length means that during insertion or withdrawl, contact is made in the socket-outlet at a stage where it is possible for fingers to reach the live pins.
(The pin length for AS/NZS 3112 is 17.06mm +/- 0.4mm) {My input}

The Chinese pins are 18.1mm +/- 0.3mm.
I've seen several plug-packs with the longer pins as well as occasional moulded cord sets on imported gear.
Plugs with these longer pins are illegal and actually dangerous; they should be discarded.
Fortunately, the move to insulated pin shanks will eliminate this hazard.


That comment came from Gary Henderson, ZL2TNH.

Hmm, longer pins, I would never have thought about that.

{Sorry about the thread-jack Aussie}

{Message edited for a couple of typo's



[This message has been edited by Trumpy (edited 01-06-2006).]
Posted By: pauluk

Re: History of the Australian plug - 01/06/06 12:04 PM

Quote
The parallel vs. tandem issue should be considered separate from the 125 vs. 250 issue......


Many thanks for that excellent explanation. [Linked Image]

This is another of those issues where things start to make sense once you get the history behind it (and I'm a firm believer that in many technical fields we should be teaching newcomers not just current standards but also enough of the historical development to give them an understanding of how we got to where we are today).

It's easy to look at these varying connector configurations today and say we could have come up with a more standardized system, but the T-slot recepts. would have been a quite logical arrangement to adopt at a time when both parallel and tandem-blade plugs were in use for the same voltage.

Re: Aussie vs. Chinese plugs:

Quote
Plugs with these longer pins are illegal and actually dangerous; they should be discarded.

While I can come up with several reasons for avoiding Chinese stuff altogether, I can't help feeling that this is over-reacting somewhat. Is one whole extra millimeter on the length of the pins really going to turn a safe connector into a shock hazard?
Posted By: SvenNYC

Re: History of the Australian plug - 01/06/06 01:29 PM

Quote
Is one whole extra millimeter on the length of the pins really going to turn a safe connector into a shock hazard?


I think it's over-reacting, but then again...the pins on our plugs sometimes vary in length by a millimeter or two.

Some are slightly shorter and some are slightly longer.

All depends on the provenance of the plug and also I guess how much rubber is deposited around the pins (in the case of a molded plug).

Some replacement plugs usually have slightly longer (and thicker) pins. They help stay in the socket better.
Posted By: Lostazhell

Re: History of the Australian plug - 01/06/06 04:49 PM

A millimeter? Considering that there is quite a variance in the actual molded rubber or plastic design with different cordset and different cord cap manufacturers, I can't see an extra millimeter on the blades being more of a shock hazard than a slimmer designed plug....

Besides, aren't most people smart enough to kinda get the idea you aren't supposed to touch the shiny metal things as they disappear into the wall outlet? [Linked Image] [Linked Image] (ok.... I might be stretching that [Linked Image] )
Posted By: yaktx

Re: History of the Australian plug - 01/07/06 01:23 AM

Quote
... there is one thing of signifigance, and thats the fact of the ground pin being longer than the current carrying blades...


Well, I don't have any crowfoot plugs handy (I've rarely ever seen them), but several such are illustrated in the 1960 WESCO catalog. They all appear to have longer ground pins.

What represents an improvement in the 5-15 (apart from backward-compatibility) is that the u-shaped ground pin is too wide to be inadvertently inserted in a live slot.

Although T-slots and older parallel devices have a 250V rating, I doubt they were ever used much on circuits over 120V, since appliances with these plugs were, and are, so common.

Any other plug could be used within its maximum rating. Crowfoots were used for 240V circuits, and for 120V grounding circuits.

I need to get my scanner hooked up, so I can post pages 198-199 of House Wiring by Thomas W. Poppe (1930). Two methods of grounding a washing machine through the cord are illustrated. One involves a crowfoot, and is essentially the same as the modern method. Let's just say the other is scary! [Linked Image]
Posted By: aussie240

Re: History of the Australian plug - 01/09/06 03:30 AM

To quote from the original aticle:
"In adopting the USA configuration, the pins of the Australian design were shortened by 3 mm in length".
Only a couple of months back I bought some more old bakelite fittings from the markets. I didn't realise it at the time but looking through my stash when I got home revealed something which I believe is of historical signifigance:
[Linked Image]
The thing I noticed about this Clipsal plug was the pins were longer than normal. Sure enough comparing to a modern plug:
[Linked Image]
It can be seen there's a difference of about 3mm.
So, it would appear that this Clipsal plug is pre Australian standards and should be identical to the obsolete US 3 pin design which we adopted. I have never seen another plug like it...and I've seen a lot of bakelite. It does go right into every socket I tried it in, so perhaps the socket depth is still required to take into account the pre 1937 standard.

While still on historical theme, to quote again
"Some American plugs, sockets and cord extension sockets were imported and these were of the flat pin type, ie 2-pin flat pin plug with the pins parallel"
This is probably one such example made by General Electric. I got it of an ancient power board which was also fitted with some equally ancient 3 pin sockets as well as some nice brass BC sockets. It's perhaps surprising there were no British sockets.
[Linked Image]
Notice it's rated for 250V use...whether those sold in the US are rated at that I don't know. One aspect of the two pin US configuration we never did adopt here was the polarised version (ie. one pin wider than the other). Since locally made stepdown transformers often use the locally made Clipsal socket it's impossible to plug in some US appliances if they have the polarised plug. Also, the local version of the plug does not have holes in the ends of the pins.

[This message has been edited by aussie240 (edited 01-08-2006).]

[This message has been edited by aussie240 (edited 01-08-2006).]
Posted By: djk

Re: History of the Australian plug - 01/10/06 12:45 AM

When did BS546 appear?
Also when did schuko first appear?
Posted By: pauluk

Re: History of the Australian plug - 01/10/06 02:31 PM

That GE socket is very similar in overall design and styling to the 5A types BS546 which were used in Britain -- Just change the slots for round pins.

Quote
When did BS546 appear?


I'm not sure of the date. I think that at least some of the original plug standards predate the existence of the British Standard.
Posted By: yaktx

Re: History of the Australian plug - 01/11/06 04:24 AM

Aussie240,

It looks like that socket says "12.5A 250V". Am I correct?

I've never seen that rating on US-made devices, although some early US parallel and T-slot devices are rated 250V or even 300V.

Although the polarized "NEMA 1-15" became the standard receptacle in the US by the '30s, polarized plugs were just about rare as hen's teeth until 1978. That's not to say they didn't exist at all. The bathroom fans in my 1971 house had polarized plugs, before I replaced them with new ones.
Posted By: Texas_Ranger

Re: History of the Australian plug - 01/11/06 06:53 PM

Schuko already existed in the 1930ies, but I have absolutely no idea when it first came up. The idea of grounding was introduced around the 1890ies according to an old code book I once got, but it didn't mention any plugs.
Posted By: aussie240

Re: History of the Australian plug - 01/11/06 10:30 PM

Quote
It looks like that socket says "12.5A 250V". Am I correct?

That's quite correct. I've never seen that 12.5A rating on anything else. The locally produced 2 pin plugs and sockets of that configuration are rated at 250V 10A.
Posted By: Trumpy

Re: History of the Australian plug - 01/12/06 05:59 AM

1mm might not sound like a lot to those of us that have fully developed fingers.
But, have you ever watched a young child insert the plug into a socket?.
There was a push here not long ago for all kindergartens and primary schools to have the recessed style socket-outlets.
This was before we adopted the AS/NZS Standard and it got lost in the rush to make both sides of the Tasman the same.
All of the Kindergartens I've been in since, still have the standard (although shuttered)socket-outlets.
I tried one with Duspols, with a gap of 12mm you can light up the neon and get current out .
Oh and BTW, there were no RCD's on this installation either, the place was built in the 70's.
Posted By: C-H

Re: History of the Australian plug - 01/12/06 08:22 AM

Ragnar,

there is a patent for a Schuko-type plug that was submitted in 1923. I thought I had posted a thread about it here maybe a month ago, but I can't find it.

Here is a link

[This message has been edited by C-H (edited 01-12-2006).]
Posted By: djk

Re: History of the Australian plug - 01/12/06 10:18 AM

I'm never quite sure what era schuko was used here in Ireland. For a time, we had several standards used simultaniously.

Schuko was certainly common in homes built in the 1930s thru 1950s.

BS546 seems to have been around always, but strongly appears in the 1950s/60s. However, it's common to see old installations where only the 15A sockets were used. Typically one per room.

The 5 and 2 amp versions didn't seem to be in widespread use until the demand for switched/dimmable table lamps became an issue and they were installed alongside BS1363 in the 1970s/80s/90s.

The 15A version also occasionally gets seen behind dishwashers/dryers/washing machines in installations from the 1960s/70s. Each appliance would have been on a dedicated circuit. The main reason for this was that 220V was the official standard here and many appliances were designed around aprox 16A loads (schuko). So, 13A fused plugs wouldn't quite cope. You'd find BS1363 throught the rest of the house though.

BS546 fitted standard boxes, schuko didn't.. hence it wasn't used.

However, we certainly had BS and VDE standards operating side by side for a considerable period of the 20th century.

BS546 and schuko were both dropped in favour of BS1363 as it created a new national standard and removed various questionable earthing arrangements with 2 pin schuko plugs in BS546 sockets etc..

Also, the shuttering etc appealled to the safety authorities at the time.

It's exceptionally rare to find a non-BS1363 outlet in normal use here thesedays. BS546 (other than for special purposes) and schuko have completely disappeared. (although you occasionally see long since disconnected round schuko outlets recessed in skirtings / wood work of some older homes. They were simply never removed as it would be too much hassle.

[This message has been edited by djk (edited 01-12-2006).]
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