Polarised plugs

Submitted: Thursday, Jun 02, 2016 at 08:55
ThreadID: 132612 Views:1901 Replies:4 FollowUps:4
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With the 2 pin polarised plugs (prongs in a T configuration), which is the positive? The ones I have use black for both wires which makes it a tad tricky. I would assume the top horizontal prong is +'ve but I'm not +'ve so thought I'd best ask.
Saving the multimeter till I need it.
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Reply By: Member - ACD 1 - Thursday, Jun 02, 2016 at 09:19

Thursday, Jun 02, 2016 at 09:19
Hi rosco

Are you ready for some confusion...

Following taken from RPC Website - The Australian standard is that the horizontal pin is the positive terminal (and the vertical is negative). However, in Victoria the top of the T is taken to look like a minus sign, and is therefore negative.

There has also been previous discussion on this site which can be found here.

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Anthony
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Reply By: Member - Boobook - Thursday, Jun 02, 2016 at 09:25

Thursday, Jun 02, 2016 at 09:25
Rosco I would get that Multimeter out. The leg of the T should be ground and the top of it +, however there never seems to be a hard standard other than the leg is earth. It is an old 32v plug adapted for vehicles.

The best place for them is in the bin, though that may not be possible if you have a gennie.
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Follow Up By: vk1dx - Thursday, Jun 02, 2016 at 09:46

Thursday, Jun 02, 2016 at 09:46
Get a multimeter and test it. Regardless of standards the multimeter will tell which one actually positive etc. Not just what is supposed to be positive.

As BB said, "the top of it +". Note the word that he used, "should".

Phil
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Reply By: Member - Chooky and Wobble - Thursday, Jun 02, 2016 at 11:56

Thursday, Jun 02, 2016 at 11:56
If you are talking about the large round plugs and sockets the same size as our 240 plugs but with the pins in a T layout, I agree with others there is no standard for how they are wired. Best get the multimeter out.
My first contact with these plugs was around 1967 where they were used as plugs and sockets to power 2way radios mounted in cars. The radios were pre transistors and built like battleships.
The female sockets to go in the vehicles were mounted on a bakelite plate that had a fuse and terminals all pre wired. The fuse was connected to the vertical of the T by a copper strap. The unfused terminal was connected to the horizontal pin also by a copper strap. Hence we wired the positive to the vertical pin.
We were told it was that way as the horizontal was like the drawing symbol for chassis of the radio in the circuit diagram.
Just a bit of history. ??

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Reply By: Nomadic Navara - Thursday, Jun 02, 2016 at 14:25

Thursday, Jun 02, 2016 at 14:25
Back in the 50s through to the 70s when I used them a fair bit there seemed to be two conventions. One had the pins mounted in a vertical line and the other had them in a horizontal line. In both orientations the pin laying in the horizontal plane was the negative pin. From the above discussions it looks like that convention has gone out the window.
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Follow Up By: Member - Chooky and Wobble - Thursday, Jun 02, 2016 at 14:41

Thursday, Jun 02, 2016 at 14:41
Peter looks like you and I have similar backgrounds. I am also a retired radio tech.
I often wondered if the reason the radio industry used the horizontal pin as negative was related to the english ties. A lot of the early radios were made by companies based in england ( pie etc).
A lot of the english cars were positive earth/ chassis. Hence the vertical pin would have been negative. A lot of the radios were also set up with their internal bits floating so they could handle either negative or positive earth.

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Follow Up By: Nomadic Navara - Thursday, Jun 02, 2016 at 15:42

Thursday, Jun 02, 2016 at 15:42
As far as I could ascertain, one stroke forms the negative symbol and 2 strikes forms the positive symbol. When you mount the socket you use the pin that looks like the negative symbol for the negative connection.

When I was in Port Moresby the OTC receiving station was in the other half of our receiving station building. OTC mounted their sockets with the pins vertical, ours were horizontal. That meant we could not take our appliances from one end of the building without re-terminating the plugs.
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Follow Up By: Member - Chooky and Wobble - Thursday, Jun 02, 2016 at 16:56

Thursday, Jun 02, 2016 at 16:56
Sounds about normal for no agreement between agancies. I was with DCA in Vic/Tas then Head Office before they moved to Canberra.

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