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It is indeed correct there was no official standard as to the live/neutral connections certainly up to the 1950's. This is why on old bakelite plugs you'll see only the "E" designation and not "L" (or "A") and "N".
However, the standards of the time did specify that the active was switched in the GPO. But, as early GPO's consisted of a separate switch and socket, there was no guarantee of polarity. There are still some reversed active/neutral GPO's in the building I work in (built 1956). I understand it's the reason why double pole switching was required in many portable appliances.
It is also interesting to note that up until the late 50's it wasn't required to earth domestic GPO's if there was no other earthed fittings in the same room. For example, in a bedroom it was not considered necessary to run an earth wire to the GPO, whereas in a kitchen it was required. I was quite suprised the first time I'd seen it for real but I can see that you could have gotten away with it.
The 32V socket is officially designated for what is termed "Extra Low Voltage" which is defined as 32V or under. Ironically, although it was meant for use in rural homes supplied by a 32V DC home lighting plant, most such installations used the normal 240V 3 pin socket...when such appliances find their way into an area supplied with 240V mains, the results are disastrous. Having to replace every valve in a 32V radio because the heaters have been blown open is not a cheap exercise! These days the T socket is popular for 12V applications (solar powered homes, boats etc.)and is considerably better than cigarette lighter plug/socket connectors. It also finds widespread use with 32V lead lights.
The 2 pin US style connector is actually not approved for connection to the 240V mains, though up until the 30's when our modified version of the U.S 3 flat pin plug became standardised, it was used along with the various round pin English connectors, and of course the ubiquitous bayonet light socket plug. However, in some very old and few and far between installations it was still used until much later where no earth connection was needed(or could be bothered with). It's main use is of course for running imported 110V appliances from stepdown transformers. I've seen it used for just about everything from 6V upwards.
Why we have the 2 round pin/flat earth pin socket made by Clipsal for 110V I can't work out. I have never seen one being used...and why would you bother? If an earth is required, the use of the standard US 3 pin socket would be more logical.
Incidentally, it used to be very common to find imported appliances fitted with 2 pin US plugs (particularly HiFi gear)to have the pins twisted to fit the Aussie GPO. And if it was a 3 pin US plug the earth pin would simply get broken off.
Standards are much tighter here now and plugs must now have the insulating sleeves part way over the active and neutral pins. Given the pins are still the same thickness, one wonders how much brass has been removed thus weakening the pins.

aussie240,
Welcome to the group!!.
I'm loosely assuming that you are Darren that Bill posted the pics for?.

Trumpy those cord-line switches in your picture are terrible. They fail the moment you insert a 100w light bulb in the table lamp instead of a 60w. I've never checked but I cant believe they are rated at 10A.

There is a also a picture of a 240V 15A socklet and a 10A.

Perhaps someone can help me out here by telling me why the only difference between our 15A and 10A socket outlets here is a larger earth socket. And ditto for plugs.

I would have thought that the normal current carrying pins & sockets ( p & n ) would have have been larger too.

If the only reason for the larger earths is to prevent plugging a 15A plug into a 10A socket, then why didn't we just up-rate our 10A sockets to 15A ?

After all, the minimum size of cable allowed to feed a 10A outlet is 1.5mm which is rated at 16A. This is still a requirement isn't it ? ?

aussie240,
Welcome to the forum!



Thanks for the notes confirming that there was no specified polarity in the past.


Ah.... So the Aussie plug was indeed based on the U.S. type then. The shape and size of the phase/neutral pins just seemed like too much of a coincidence for there to have been no connection.


Could it be simply a case of circuit arrangements in the past requiring a distinction between 10 and 15A for loading/fusing purposes?

The NEMA standards in America use exactly the same shape and size prongs on 20A plugs as the 15A types, but oriented such that a 15A plug will fit a 20A socket, but not vice versa.,

Actually "isolated location" would still be legal in Germany and Austria, but with central heating it would be close to impossible not to have any grounded metal surfaces in a room.
Austria never really cared about the "no other grounds" requirement much anyway... I've seen loads of ungrounded and Schuko receptacles side by side...

No, just found this forum whilst searching for porcelain light sockets

Re the 10A & 15A sockets, I bet the 10A sockets and plugs really would carry 15A just as safely as their official 15A cousins. Also don't forget the 32V plug is rated at 15A and has the same physical pin dimensions.
The idea of having a 15A vs 10A GPO is as I recall simply to limit the use of one high power appliance per circuit.
To try and explain, imagine if we did have our homes fitted with 15A GPO's in every room. The problem would occur if an appliance drawing 3.6KW was plugged in and there were also other appliances on the same circuit. The power circuit would then be exceeding its 16A rating. It's really just a way of encouraging a dedicated power circuit to a particular high power appliance.
Naughty people still file down the earth pin and plug into a 10A socket,however.


I've got an article from "Amateur Radio Action" some years back where Mr Clipsal himself speaks on this topic (sorry I can't remember the guy's real name). In brief, the story goes that both imported US and UK fittings were used in the beginning (more so UK...certainly as far as the bayonet light socket goes anyway) and when Clipsal were looking at manufacturing locally they found it much easier to make flat pins than round ones. And, as earthing of the domestic supply was standard, it was the 3 pin version of the US plug & socket that we ended up with. The article goes on to mention that the pins of the locally made plug were shortened by about 2mm to improve safety.
I actually picked up an ancient workshop power board a few years ago fitted with brass light sockets, what must have been the first generation of bakelite Australasian 3 pin sockets, and some nice GE made 2 pin US sockets. They were wired to 240V along with the other fittings.
I'd be fascinated to see if the present Australasian 3 pin plug does actually fit the US 240V socket.

{ Edited just to tidy up quotes - Paul }


[This message has been edited by pauluk (edited 07-13-2005).]

A similar arrangement was used with the old BS546 (round-pin) outlets in the U.K. It was the norm for a 15A socket to be wired on its own dedicated 15A branch circuit (there was typically just a single 15A outlet in each main room, often beside the fireplace, for obvious reasons).

Multiple 5A sockets used for smaller portable appliances were then wired on the same circuit. Although the IEE regs. at one point did specify no more than three per 15A branch, it was very common to have many more than this number, and not likely to be a problem with the typical loads in use. 5A sockets were also common on lighting circuits, protected by a 5A fuse.

It won't, at least not unless you twist the blades out of shape.

The 240V 15A NEMA plugs have the blades horizontal (i.e. both blades are turned at 90 degrees compared to the regular 120V plug so that they are in line rather than parallel to each other).

The 20A versions have one vertical and one horizontal blade and the 20A receptacles have one slot arranged as a "T" so that it will accept the appropriate 15A plug as well.

Have a look here for the different configurations:

http://www.leviton.com/sections/techsupp/nema.htm


(It's not clear from the diagrams, but the 15 and 20A types are the same size physically. 30A and above are much larger, both on pin size and spacing.)

There is an an obsolete, ungrounded 120/240V 20A (NEMA 10-20) that has the same pattern and looks close to the Australian plugs but the pin spacing is a little different.

[This message has been edited by IanR (edited 07-13-2005).]

Thanks for the link Paul...I was actually thinking more along the lines of NEMA 10-50.
We had 6-30 type plugs on our DEC PDP-11 mainframes here which I saved when it was all scrapped. This one also looks like it'd take an Aussie plug https://www.electrical-contractor.net/Nostalgia/Odd-Recept.JPG

Thanks for the replies Aussie and PaulUK. So the larger earth pin is to encourage dedicated circuits for higher power appliances. That makes sense.

I suppose in an "ideal world" all sockets in a house would be 15A with a dedicated 20A supply cable to each one and 15A RCCBO protection.

This is economically unfeasible and means the DB would occupy half the garage !

BTW. PaulUK, your Lions Should be arriving home any minute with their tails between their legs. And Aussie 240, the All Blacks will be arriving on your door-step soon. Good Luck !