Positive or negitive for 12v 2 pin plug plug

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.

Vertical is (-) when I use them.

Think you will need to check further for yourself.
I had a camper trailer that came wired with + vertical and - was horizontal

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!

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 !

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

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.

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.

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.

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.

We (family and friends) have always wired the horrizontal (or top part of the T) as neg and the vertical as Pos.
Neil

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.

My T plugs were wired up by an auto leccy and the top is positive

I would have to choose the the same as the honda gennie or I could end up blowing fuses or worse.

Owen

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.

Has anybody put a multi-meter on a generator 12v output socket, surely that would give more than a clue!