Positive or negitive for 12v 2 pin plug plug

Submitted: Sunday, Feb 17, 2008 at 23:42

Member - LOS BUSH

Which terminal is the Negitive for the 2 pin 12v plug that looks similar to the 3 pin x 240v plug on an extenion cord.Is it the one that is vertical and is in a similar position as an extenion cord or the horizontal terminal that looks similar to a _ or negitive sign.Is there a standard or some general convention
ThreadID: 54688 Views:7229
Replies:16 FollowUps:17
This Thread has been Archived
Back Expand Un-Read 0 Moderator

Reply By: disco driver - Monday, Feb 18, 2008 at 00:20

Monday, Feb 18, 2008 at 00:20
Hi,
AFAIK there is no set system although most I know use the horizontal pin or socket as the positive(+) and therefore the vertical as the negative(-).

It depends on who wires it into the vehicle system.

When I wire them on my vehicles I usually wire back direct to the battery terminals and fit suitable fuses (and switches if required) to the positive cables.

Others may do it differently.

Disco.
AnswerID: 288083

Follow Up By: Mainey (wa) - Monday, Feb 18, 2008 at 08:26

Monday, Feb 18, 2008 at 08:26
Yes, there IS a set system, and Disco as you say the top or horizontal is the 'positive' and the lower or vertical is the 'negative'

Mainey . . .
0
FollowupID: 553350

Follow Up By: Nomadic Navara - Tuesday, Feb 19, 2008 at 13:27

Tuesday, Feb 19, 2008 at 13:27
It's all very well to talk about vertical and horizontal pins, but which way do you mount the plug?

The old DCA standard was to mount the 2 pins in a horizontal line and the one that looks like a negative symbol is the -ve.

The old OTC standard was was to mount the two pins in a vertical line and again the one that looks like a negative symbol is the -ve.

That is how I would expect them to be wired - according to the way you mount them.

PeterD
PeterD
Retired radio and electronics technician
Lifetime Member:My Profile  Send Message
0
FollowupID: 553580

Reply By: Derek from Affordable Batteries & Radiators - Monday, Feb 18, 2008 at 00:31

Monday, Feb 18, 2008 at 00:31
Vertical is (-) when I use them.
ABR - SIDEWINDER
Business Member: My Profile  My Blog  Send Message
AnswerID: 288085

Follow Up By: Member - LOS BUSH - Monday, Feb 18, 2008 at 00:45

Monday, Feb 18, 2008 at 00:45
Disco ,Derek Thankyou for your reply - Los


0
FollowupID: 553337

Reply By: Outnabout David (SA) - Monday, Feb 18, 2008 at 07:26

Monday, Feb 18, 2008 at 07:26
Think you will need to check further for yourself.
I had a camper trailer that came wired with + vertical and - was horizontal
AnswerID: 288097

Reply By: Dave from P7OFFROAD Accredited Driver Training - Monday, Feb 18, 2008 at 07:54

Monday, Feb 18, 2008 at 07:54
The 'convention' is for positive to be on top! Negative under it!

Assuming that you recognise it as a T plug and place it that way!


Good choice BTW!
AnswerID: 288099

Reply By: Member - bungarra (WA) - Monday, Feb 18, 2008 at 08:50

Monday, Feb 18, 2008 at 08:50
as others have posted...the "top" is positive

a simple way of remembering is the following example I tell people who ask me

when viewing the plug as a "T"

The Horizontal is positive, the HOT end H = H
The vertical is naturally negative as in a 240v 3 pin plug

as others have said..... always fuse your lines, or at least every accesory, as under Murphys law someone, somewhere will get it wrong and you cannot guarantee that your device or leads may get used or swapped one day by some innocent soul !
Life is a journey, it is not how we fall down, it is how we get up.
VKS 1341
AnswerID: 288103

Reply By: Tony MD - Monday, Feb 18, 2008 at 09:04

Monday, Feb 18, 2008 at 09:04
There is no standard. Always check polarity first.
Wicen Victoria
use the top horizontal pin as negative. The link also states that it is believed that Wicen NSW uses the top horizontal pin as positive; this as I first learnt as an apprentice electrician 30 odd years ago!
WICEN is the Wireless Institute Civil Emergency Network.
Cheers, Tony
AnswerID: 288105

Follow Up By: Mainey (wa) - Monday, Feb 18, 2008 at 09:22

Monday, Feb 18, 2008 at 09:22
How things change
I back Derek's and others posts that the top is the (+) terminal connection in a *12v power* system.

Mainey . . .
0
FollowupID: 553360

Reply By: Member - Kiwi Kia - Monday, Feb 18, 2008 at 10:13

Monday, Feb 18, 2008 at 10:13
In my electrical circles it has been convention to use the horizontal as negative. Easy to remember as horizontal ----- looks the same as negative --.

As has already been mentioned this is convention only.
AnswerID: 288117

Follow Up By: Member - Kiwi Kia - Monday, Feb 18, 2008 at 10:18

Monday, Feb 18, 2008 at 10:18
I should also have said that I am refering to the plugs that are similar in size and shape (other then pins) to the 230 V plugs as this is what the original question refered to. On the small line conectors as found on motor vehicle wiring looms its the other way around.
0
FollowupID: 553367

Reply By: Member - Mike DID - Monday, Feb 18, 2008 at 11:27

Monday, Feb 18, 2008 at 11:27
Where there are two ways of doing something, there will be two "standards" e.g. which side of the road to drive on - unless there is a body to publish a firm standard.

That never happened for the T plug.

Fortunately the other moderrn DC connectors don't have that problem -
- Cigarette Lighter - centre always positive
- Merrit Socket - centre always positive
- Grey 50 and 175 amp Anderson SB - polarity s marked on the connector.
- Red/Black 30 amp Anderson Powerpole - red is positive.

The T connector is falling out of favour, not just because of the problem of reverse polarity damage, so you would be better off changing to one of the more modern standard connectors.
AnswerID: 288125

Reply By: Gone Bush (WA) - Monday, Feb 18, 2008 at 11:28

Monday, Feb 18, 2008 at 11:28
Don't confuse poor old LOS.

Tell him it's vertical for negative and it's referred to as a T (tee) plug.

All he has to do then is turn all his plugs up the right way and re-wire them.

cheers LOS.
I'm glad I ain't too scared to be lazy
- Augustus McCrae (Lonesome Dove)
Lifetime Member:My Profile  My Blog  Send Message
AnswerID: 288126

Follow Up By: Member - LOS BUSH - Monday, Feb 18, 2008 at 11:55

Monday, Feb 18, 2008 at 11:55
Listen Bush,enough of the "poor old Los" stuff. I thought you could not resist the temptation to place a post.You told me I was the only one on earth that had a horizontal Negative.It is obvious that many are unsure and do what suits them as there is no standard, only a flimsy convention Why would I turn the plugs around I am happy the way they are. Los
0
FollowupID: 553385

Follow Up By: Gone Bush (WA) - Monday, Feb 18, 2008 at 18:39

Monday, Feb 18, 2008 at 18:39
LOS it seems like half of Australia wires these plugs like you do and half like I do.

I learn something every day. Sorry to sound like a smartypants it sure wasn't meant that way. I'll have to use "lol" a lot more (lol = lots of laughs).

When it's time to re-wire your Effie we'll talk about Arrid/Merit plugs and sockets. They are very good.

cheers

I'm glad I ain't too scared to be lazy
- Augustus McCrae (Lonesome Dove)
Lifetime Member:My Profile  My Blog  Send Message
0
FollowupID: 553454

Follow Up By: Member - LOS BUSH - Monday, Feb 18, 2008 at 20:15

Monday, Feb 18, 2008 at 20:15
Thank you Bushy We seem tohave more in common than our surname
see you 'round Los Bush
0
FollowupID: 553467

Reply By: Member - Mike DID - Monday, Feb 18, 2008 at 12:03

Monday, Feb 18, 2008 at 12:03
There other reason that there are two "standards" for wiring these plugs, is because there are two ways of wiring them, and for EACH, it's obvious that it's the logical way to wire it -

T - the vertical is earthed, because it looks like the Earth on an Australian Mains socket.

Inverted T - the horizontal is earthed, because it looks like the earth and like a Minus sign.
AnswerID: 288131

Follow Up By: Member - LOS BUSH - Monday, Feb 18, 2008 at 12:40

Monday, Feb 18, 2008 at 12:40
G'day Mike, Thanks to you and others for their interest, LOS
0
FollowupID: 553390

Reply By: res.q.guy - Monday, Feb 18, 2008 at 15:00

Monday, Feb 18, 2008 at 15:00
We (family and friends) have always wired the horrizontal (or top part of the T) as neg and the vertical as Pos.
Neil
AnswerID: 288147

Reply By: Dunaruna - Monday, Feb 18, 2008 at 18:11

Monday, Feb 18, 2008 at 18:11
I agree with the majority, I alway use the vertical as the negative.

Just to clear up something though, there is no official Australian standard for this type of plug.
AnswerID: 288176

Follow Up By: Member - Kiwi Kia - Monday, Feb 18, 2008 at 21:18

Monday, Feb 18, 2008 at 21:18
Dunaruna, Just to keep the argument (discussion) going :-)) What makes you think you are in the majority ?

I would also point out that the 'T' plug used to be common in electrical equipment to indicate 110 V ac and not 230 V ac !
0
FollowupID: 553491

Follow Up By: V8 Troopie - Monday, Feb 18, 2008 at 21:45

Monday, Feb 18, 2008 at 21:45
You may confuse it with the plug that has two parallel flat pins as used in the American system.

The 'T' plug is a designated LOW VOLTAGE plug and low voltage only goes up to 50V.

Me thinks its illegal to use these 'T' plugs for 110VAC and I have never seen them used for that.

If you need to distinguish 110V from 240V it may be best to use the plug with a round earth pin and two flat, angled pins for active and neutral.
Klaus
0
FollowupID: 553502

Follow Up By: Dunaruna - Monday, Feb 18, 2008 at 21:54

Monday, Feb 18, 2008 at 21:54
Kiwi, 11 people posted an opinion as to which slot should be negative. 4 said the horizontal, 7 said the vertical. That's a majority, I was agreeing with the majority.
0
FollowupID: 553504

Follow Up By: Member - Kiwi Kia - Monday, Feb 18, 2008 at 22:14

Monday, Feb 18, 2008 at 22:14
V8 Troopie, Sorry, I should have said American 110 V and no, I am not confusing it with the flat parallel pin plugs.
Those 'T' plugs were very common on 110 V transformers about 30 years ago.

Also, you are a bit behind the times. 230 V IS low voltage (anything below 400 V). Part of the change is to do with allowing non-registered people to work on 110 V (fork lifts etc). 110 V is also commonly used on European machinery and is derived from 110 volt centre tapped transformers giving a swing voltage of 55 volts each side. The worst voltage you can get to earth is then only 55 V. Great for safety & control circuits.
0
FollowupID: 553513

Follow Up By: Mike Harding - Tuesday, Feb 19, 2008 at 13:56

Tuesday, Feb 19, 2008 at 13:56
>The 'T' plug is a designated LOW VOLTAGE plug and low voltage >only goes up to 50V.

I suspect you're thinking of "Extra low voltage" which is below 50V AC or 120V DC.

Low voltage is above ELV and below 1000V AC or 1500V DC.

A quick look suggests Clipsal rates these plugs/sockets at 32V (they don't say AC or DC but I suspect it's DC).

Mike Harding
0
FollowupID: 553585

Reply By: Muzzgit [WA] - Tuesday, Feb 19, 2008 at 00:22

Tuesday, Feb 19, 2008 at 00:22
My T plugs were wired up by an auto leccy and the top is positive
AnswerID: 288249

Follow Up By: Member - Mike DID - Tuesday, Feb 19, 2008 at 13:58

Tuesday, Feb 19, 2008 at 13:58
Which just goes to show there isn't even an agreed convention as to whether the top or the bottom will be positive !


"Tony MD replied:
There is no standard. Always check polarity first. Wicen Victoria use the top horizontal pin as negative "


0
FollowupID: 553586

Reply By: obee - Tuesday, Feb 19, 2008 at 08:20

Tuesday, Feb 19, 2008 at 08:20
I would have to choose the the same as the honda gennie or I could end up blowing fuses or worse.

Owen
AnswerID: 288257

Follow Up By: Member - Mike DID - Tuesday, Feb 19, 2008 at 20:19

Tuesday, Feb 19, 2008 at 20:19
On the Kipor Generator it's mounted as an Inverted-T (I over -) with the lower Minus as Negative.
0
FollowupID: 553661

Reply By: Member - Mike DID - Tuesday, Feb 19, 2008 at 13:41

Tuesday, Feb 19, 2008 at 13:41
Keep in mind also that there are TWO SIZES of T-plugs.

The ones that have been used in Australia for decades have a 15mm gap between the pins.

The ones that provide the battery charging output (unfortunately mis-labelled as DC Out) have a 6mm gap between the pins.
AnswerID: 288296

Follow Up By: Member - Mike DID - Tuesday, Feb 19, 2008 at 13:48

Tuesday, Feb 19, 2008 at 13:48
3rd sentence should read -

The ones that provide the battery charging output (unfortunately mis-labelled as DC Out) from portable generators have a 6mm gap between the pins.
0
FollowupID: 553582

Reply By: Shaker - Tuesday, Feb 19, 2008 at 14:04

Tuesday, Feb 19, 2008 at 14:04
Has anybody put a multi-meter on a generator 12v output socket, surely that would give more than a clue!
Anyone who lives within their means ..... suffers from a lack of imagination!
AnswerID: 288298

ExplorOz Shop Suggests (12)