It accepts the plugs on my Aussie radios. It's a Leviton 5024. These apparently predate our modern grounded outlets, the ones with a pair of parallel slots and round ground pin. Leviton is a major manufacturer of plugs and outlets and switches.

I'm happy to thank American inventors for that plug design. I've travelled a lot on every continent and I still think this is the best universal 220-260v standard socket, by far. It enforces polarity, it resists accidental insertion of round objects, and it provides independent earth. That said, there have been times in my travels when I have chosen to make connections by poking bare wire ends into round-hole unswitched 220v sockets. I won't mention that this was in certain large Asian countries, and many years ago.

I'm curious why the US standards bodies didn't adopt the sad-face socket, made famous in the painting "The Scream". Possibly because the power systems were privately owned and didn't want to pay patent royalties?

By contrast, the British 15 amp standard plugs are massively over-specified, and the size and thickness of the tines actually reduces safety because it is easier to poke something inappropriate into them.

Maven

I just realised what's wrong with that picture. The slots look much wider than standard and the contacts look very shallow but it might be because of the camera angle and flash. It seems to have 250v on it though.

They are almost identical to the old commercial mechanisms made here by Wilco, Ring Grip and Clipsal in the 1930s and 1940s. They were seldom seen in domestic situations because most electrical installations were still surface-mounted split-seam conduits with red cedar mounting blocks and round surface switches and sockets right up to the late 1960s when Australian manufacturers developed their own 'allways' plates and mechanisms which could be rotated depending on whether you wanted the plates mounted vertically or horizontally. Australian 'standard pattern' plates for all flush-mounted mechanisms are the same as the American one.

In order from left to right, a modern surface switch, a white Clipsal 2-pin surface socket, a Ring Grip 3-pin surface socket, a Clipsal 3-pin surface socket, a brown Clipsal 2-pin surface socket, a white Clipsal junction box socket, a white Clipsal 2-pin flush-mount socket mechanism and matching switch mechanism. Note that all of the sockets are rated at 250V 10A though the 2-pin ones were more commonly used for extra-low voltage situations, usually 12 volts for the parallel pinned version shown here and 32 volts for the polarised version which looks a bit like the letter T. One place you will find the 2-pin socket used for 240 volts is when they were installed on the back of radios to power a turntable.

There was another version of the round surface switch too - no screws were used to hold the front cap on. Instead it screwed on around the switch dolly, a bit like a lid on a Vegemite jar. This was before an amendment to the SAA Wiring Rules that barred any electrical accessory being installed below 2.4 metres that could be disassembled without the use of a tool.

Update: I almost forgot to mention - Australian socket outlet switches and light switches are up for off and down for on, following the practice of the Mother Country.

‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

This plug design has existed at least since 1915, as it shows in this patent:

In a way, Aussie light switches and American light switches are consistent in that you flip them to be closer to the North Star Polaris when you want the lights on.

As for the contacts in the pictured outlet looking rather exposed, it is due to the camera flash. My pinky finger can only get within about 3mm of the contacts when I press it on the slot.

"I'm curious why the US standards bodies didn't adopt the sad-face socket,"

Read more: http://vintage-radio.com.au/default.asp?f=2&th=344#ixzz2cT5H9lZU

They did, these were installed in US homes right up until 1960s, usually for large 230v window air conditioners.

They were probably phased out because 110v appliance plug blades could be bent to plug into these. In other words, not idiot-proof.

Yes, blade-bendng is not unknown here, though pure 110v appliances are rare. Even rarer after being plugged into 240v. Sometimes imported small appliances such as audiovisual double-insulated things have voltage adjustment settings, and that's when blade-bending can come into play. One of many things that are common, though not advisable.

Maven

Some 110 volt plugs have very little in the way of shrouding to space the pins away from fingers and these were often used on compact cassette players from the 1970s. Such items were often fitted with a 110/240 slide switch and the pins on these plugs were often found bent to suit the angled pattern.

Three issues would prevent such a plug being fitted these days (in the Australian market at least).

1. The flexes were single-insulated figure-8 which is a big no-no now.
2. The body of the plug top wasn't wide enough to keep fingers away from the pins.
3. Twisting the pins means that a portion of the pin will not enter the powerpoint, creating an arcing/fire risk.

I'll put up a picture of such a plug tonight.

‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

There is a comprehensive article on the origin of the three pin plug in Australia in Amateur Radio Action Vol. 9 No. 12 pp 28-29.

This is too long to give verbatim, but the decision was made in 1934 at a meeting called by SECV (State Electricity Commission of Victoria) with SECV , Standards Association, General Electric, Ring Grip and Clipsal representatives. They adopted a 3 pin set-up already manufactured in Australia by Ring Grip and Clipsal based on the US three pin set-up, but with 3mm shorter pins to avoid wrongful insertion and finger contact.

This led ultimately to Standard Specification AS-C112 for plugs and sockets in 1937 and was adopted by all State supply authorities (and New Zealand too).

Can supply a pdf to anyone interested.

Thanks for the detailed explanation.

Can supply a pdf to anyone interested.

Perhaps Brad can place that in the Tutorials section.

"..the [plug format] decision was made in 1934.."

A few questions arise, first that's a rather late date for standard setting, and why didn't they follow the UK as they did in other things?

I guess the situation in the UK with electrification was rather helter skelter in the early days (different voltages, DC, AC, various plug styles)

Or maybe they didn't like that big clunky English plug, can't blame them.

From what I can see, the decision was based on the fact that "Australia was committed to the earthing system of supply", so three pins were needed. As the US 3-pin set-up was already manufactured in Australia by Ring Grip and Clipsal, it got the guernsey, with modifications to pin length. A practical matter was that flat pins were considered easier to manufacture than round pins.

A few questions arise, first that's a rather late date for standard setting, and why didn't they follow the UK as they did in other things?

Most things in Australia fall into two groups. Either they were invented here or are a blend of the most useful aspects of British and American inventions.

Notable local inventions include postage stamps, cement trucks, the rotary lawnmower, lamingtons and the protocol for wireless intranet networks (WiFi).

Australia's electricity networks run the British three phase 415/240 volt system as it is simple and high enough in voltage to reduce current flow so that physical infrastructure can be smaller. The socket outlet pattern is one that was originally developed in the US because it was already being tried here, though once circular surface-mounted mechanisms fell out of favour and replaced by flush-mounted mechanisms, the American standard pattern wall box was also adopted as well. Plates were simply screwed fast and the British plates were not compatible. Six switch mechanisms can fit on an Australian switch plate and mechanisms can be popped out and turned so the plate can be oriented vertically or horizontally.

Up until the early 1950s there was a mix of the Australian socket outlet and the British bayonet light sockets in use for powering appliances like irons, toasters and radios. Quite often, the fact that an appliance wasn't earthed didn't seem to concern anyone, despite any three pin socket outlet requiring an earth wire to be fitted. The loungeroom light socket suspended from the ceiling could be fitted with a Y adaptor by the 'man of the house' so the radio could be plugged in for the night's listening pleasure though it was quite common to see mounting blocks in the kitchen fitted with a switch which controlled both a three pin socket and a light socket. Edison Screw light sockets were pretty much unheard of outside government and industrial applications.

From memory, the standard pattern plate is 110mm X 77mm. Though a square plate is also available which housed two of the old clunky Ring Grip rocker switches which date back to the 1930s. A third size, close to 110mm X 200mm housed three such mechanisms.

The Australian pattern socket outlet is used in all states and territories of Australia, plus New Zealand, Papua New Guinea, Fiji and other Pacific Islands, China, Argentina and Brazil. China orients their sockets upsidedown and Brazil transposes their active and neutral connections. Australia is one of few countries that mandate the use of switches to control sockets. The only permitted alternative is to provide an automatic socket, which isolates the power before the plug is completely removed from the socket.

Personally, I am not a fan of the British sockets. It is much easier for young people to stick things into them and there is a widespread perception that the fuses in the plugtops make Britain's system safer. I fail to see where this is the case.

For more information, see AS 3112.

‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

I've put together this image which shows the pin patterns used in Australia since sockets came into general use. I'd say there's a fair chance most of you will never have seen some of these.

The two four pin outlets in the middle of the image with the switched and unswitched actives are for luminaires with an emergency lighting fixture inside. This allows the lamps to be turned on and off as normal but also provide a 'hot' active to keep the batteries charged.

‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

"Personally, I am not a fan of the British sockets.."

According to your link China also rejected this format despite its established use in (more advanced) Hong Kong.