Thread: Trailer Plugs

Smidsy, I had one mechanic in WA not approve the inspection (for a transfer of rego) of a ute of mine becuase it had the large round 7 pin. He claimed they were illegal in WA. I fought that one and won.
As far as I know, all types are 'legal' in all juristictions, it's just that you'll find more of one type in certain area's.
Large Round vs. Small Round vs. Flat, bit like the Holden vs. Ford, Nissota vs. Toyan or Engel vs. Waeco type arguments.
You need to assess the likely scenario's you find yourself in and make a descision to 'conform' or be a loner. Of course there are adaptors, which I don't like, because of the additional points of failure that gets introduced. Another option which can be done quite well is to actually have all 3 types of sockets wired into the 'tug', but it's impractical to have two or more leads on the trailable item though.
Food for thought?
Cheers,
Wahoon.

Legalities aside, I find the 7 pin flat plugs highly unreliably compared to the longer-pronged circular plugs. It could be due to crappy brands, but I often find myself using a blade to spread the stubby pins of the flat plugs to get all the lights working before moving off, never so much with circular plugs.

Each state seems to have their adopted plug, and there really is no right or wrong. There is a push for the 7 & 12 pin flat to become the Australian Standard, but if you look at how long it took to get the speed limits for towing different sized trailers uniform across the country.

My personal choice, 12 pin flat on the tow vehicle. Mainly because I can have an unbraked box trailer with a 7 pin flat for its rear lights, or a big tandem with Electric Brakes, reversing lights and charging for the Breakaway unit, all in the one plug.
Also, there is no confusion with two different wiring options for the flat plugs, whereas the large 5 & large 7 pin round predominantly used here in Victoria has the indicators in two different locations, but the plugs will interchange. So a car wired to 5 pin, towing a trailer with Electric Brakes will intermittently lock its brakes in time with the right indicator!!

"but if you look at how long it took to get the speed limits for towing different sized trailers uniform across the country."

Yonnee, not quite correct, in WA, can only tow any trailer at a maximum of 100km/h. Even on a 110km/h sign posted highway.
All other states can tow (up to a limit) to the signed speed limit, ie my 1999kg boat on tandem trailer I can tow at 110km/h where roads are signposted in SA to do so. COnversely though, my box trailer with a 749kg capacity, I can tow heading west at 110km/h, but west of border village, even though the highway continues to be signposted at 110km/h, only permitted to tow at 100km/h.

Uniformity is not quite there yet.

Cheers,
Wahoon.

I've lived in QLD all my life and by far the preference for all most all that I speak to for light trailers is the small 7 pin round.


Generally the large format plugs are used on heavy vehicles, because they have a higher current carrying capacity.

Lots of trucks, particularly council tippers you will see both large and small 7 pin sockets mounted in the rear of the vehicle along with the 5mm ball ring feeder combination hitches.

One common place you will find 7 pin flats is on the ford factory towing packs.

I have had some experience with the flat format plugs, and they are almost without exception crap....the problem is in the format and the way the plugs are made.....I have seen plugs with screws striped in the electrical terminations, pins that are not firm in the mouldings and as has been said pins that fail to keep tension.
Some of this may be due to poor manufacture, but a lot of it I put down to how the plug is designed making them almost impossible to make a quality durable product.

One bloke i knew who had a habit of borrowing trailers and did a bit of caravan delivery, had a string of all known trailer plugs sitting in his boot.
all he did was pull out the one he needed and hung it out thru the boot seal.

Stay with ya small 7 pin round.

cheers

Thanks guys.
I think I will use the round plug, I have used these in WA for 20+ years without a problem - also, having this plug makes it hard for people to borrow the trailer hehe.

Soundman, I've noticed a lot of new cars are wired like that - the plug is on a flat ribbon cable without an external mounting that just hangs out the boot when needed.