Apart from early types, there seems to be four main variations of three pin power plugs used in Australia over the years. The first are Bakelite with the screws and wires exposed in an open base. The second is very similar but with the screws and wires enclosed. The third is a more modern rounded looking Bakelite plug that came in various colours and the fourth is the flexible plastic plug that is still with us today. Apart from the modern plug changing to have insulated pins in 2004 and the neutral and active pins being specified some time during the 1950's, I can't find any information to date when the different styles were intruduced.

I've seen a lot of 1950's radios with modern plastic plugs on them as well as a few that had enclosed Bakelite types. For my own radios I like to keep original bakelite plugs on them if possible but only if they're in good condition. If I sell a radio it gets a modern plastic plug, mainly because good original bakelites are getting scarce. Whether selling an untagged vintage radio with a plug is a good idea or not is a whole other discussion but I'm not going to single handedly try to idiot proof the world and if I've restored it I'm happy to pass it on. Unrestored loses its plug.

Cheers,

Warren

Edit. As a footnote here, an overnight soak in a small glass of warm water and half Steradent denture cleaning tablet followed by a scrub with an old toothbrush brings an old bakelite plug up like new.

Interesting question.

I guess the best reference source would be HPM and Clipsal and Ring Grip trade catalogs of the day. Photos or ads in RT&H may also give some sort of a guide.

The first type that you mention I refer to as suicide plugs.

Good tip regarding Steradent.

Try some info here
Plug History

^ Good article. I added Ring Grip to my earlier post.

At one time or another, I have lived in houses where all of those GPO styles were in use.

It is a good article.

I'm guessing the modern plastic plugs were introduced sometime in the 60's as I can remember them when I was young. Most AWA B15's I've encountered have them fitted but not all AWA 573MA's so that puts them in the late 50's or early 60's. Judging from the radios I've seen them fitted to, the open suicide plugs (very appropriate GTC) are from the late 30's through to just after the war. This isn't particularly accurate as many radios originally came from the factory fitted with a bayonet plug, the 3 pin plug would have been fitted later. The other two enclosed bakelite styles are a bit of a mystery, the rounded ones I've seen referred to as from the 1970's and have also seen them fitted to radios from the 1950's.

All the manufacturers seem to have followed the same designs very closely with very minor variations and I suppose it's possible some styles were manufactured in parallel for different applications. I bet there's collectors out there that specialise plugs. I recently saw a pale green damaged HPM Bakelite sell for nearly $40 on eBay! The seller is an acquaintance of mine and he was astounded, he was going to throw it out.

I recently saw a pale green damaged HPM Bakelite sell for nearly $40 on eBay! The seller is an acquaintance of mine and he was astounded, he was going to throw it out.

There was an auction for 3 old power points recently. I nearly bid, but reminded myself I have more than enough junk already. They went quite cheaply. I hope some fool didn't buy them to put into use.

I still have some 1940's NOS HPM light switches that belonged to my grand father and were surplus when he built his house. Yes, he was a hoarder also Think I have some power points as well.

There were a few other makers of plug tops and sockets. I will list those I can trace tomorrow. They all eventually either folded or got consumed by Clipsal and HPM.

At my previous workplace we had buildings with a mix of Bakelite accessories, with one featuring everything including gasoliers from the late 1880s up to fairly recent standard pattern switch plates with the 'allways' mechanisms. In between there are Wilco and HPM US-pattern plates with mechanisms that fasten to the wallboxes, ie: separate switch and socket mechs screwed to the wallbox and then a plate screwed to the mechs. These are a 30s and 40s thing. There were also mounting blocks with the circular fittings available at the same time and ceiling switches. I like ceiling switches and have been known to install them in suitable locations as soon as last year. They are good particularly for two-way switching because the person using them isn't left with the oddball situation where one of the switches is in the 'on' position when the lights are out.

Note that British-aligned systems (including Australia) see the light switch up for off and down for on under normal circumstances. US-aligned systems are the opposite.

The USA used plugs and outlets of the Australian pattern before our more modern grounding pattern

I've used these to power my Aussie radios off 240V60Hz, here our power companies supply homes with a pair of 120V lines, essentially 240V with a grounded centertap. As my Aussue radios all use power transformers, they don't care that the mains pins are both hot.

Note that British-aligned systems (including Australia) see the light switch up for off and down for on under normal circumstances. US-aligned systems are the opposite.

I wonder if the US convention derives from knife switches, where you push them upwards to close the circuit. (Having them operate the other way would be unsafe as gravity could intervene.)

I just got my first bakelite female mains socket for an extension cord It's the first time I've seen that.

It's the first time I've seen that.

Not too many of those survived being dropped.

I recall many of them being taped up.

I wonder if the US convention derives from knife switches, where you push them upwards to close the circuit. (Having them operate the other way would be unsafe as gravity could intervene.)

Not that I am aware of. When I worked for the Department of Health I came across a few switchrooms equipped with knife switches (big three phase ones, carrying hundreds of amps) and they were also oriented for off/up and on/down. The danger isn't with gravity as there is a correct procedure to follow with knife switches and they are very well made anyway. You need to use a bit of force to move them in either direction. The big danger is being in such a switchroom on your Pat Malone and tripping/slipping and falling face first into one. There is no guarantee of surviving such contact with them and I would imagine that any switchroom constructed today would most definitely not be fitted with them. They'd break just about every rule in the book.

Circuit breakers switch up for on and down for off though. This is from Email following Westinghouse designs in the manufacture of most of all locally made circuit breakers and other companies just followed the precedent. HPM, for a while, went the other way but their foray into breakers was short lived because Email pretty much dominated the industrial and commercial sector with their E, F, FB, K, KA and J Frame breakers along with the later Quicklag series. Long after the demise of the E Frame series, Email sold a mounting kit to permit the installation of FB Frame breakers on E Frame boards. These days, European DIN rail breakers are taking over.

Not too many of those survived being dropped.

Some manufacturers sold rubber boots for extension sockets to help prevent breakages. This didn't prevent a socket breaking when squashed though.

There's a lot of new laws regarding extension cords and a few of them are mighty inconvenient which has lead to greater popularity of battery-powered tools. These include no daisy-chaining of cords. You can link a maximum of two cords with an RCD-protected power board known to those on building sites as an 'orange box' but the two cords cannot be directly connected with or without the time-honoured reef knot. Cords cannot any longer run on the ground or on form work. They have to be suspended on poles. All cords have to be retagged once a month or removed from the site. Of course, on many building sites all of the above is flagrantly ignored. About 70% of electrocutions in Australia are due to faulty flexible cords.

With a 35 metre driveway I think I successfully manage to break most of those rules every time I get the blower out to clean it!

I have two brothers that are builders. One carries on blissfully and intentionally unaware of most of the new rules, instead using the safety practice's he learnt as an apprentice 30 years ago. For example, no fancy harnesses when working on a roof but do make sure you clear the surrounding ground of rocks and stakes so that when you fall you minimise injury and don't skewer yourself.

The other brother religiously studied and implemented every new rule that came about. The builder is ultimately responsible for the safety practice's of all trades that work onsite and in the end he was so stressed about keeping up to date that he decided it was practically and financially impossible to do. He's given away building work all together and only does consultancy work now.

Thanks for the article Scraps as it is interesting to see what went on 50 or more years ago.

Plenty of old suicide wiring and plugs in those days.