Best 12 pin trailer plug

Submitted: Saturday, Apr 19, 2014 at 18:48
ThreadID: 107367 Views:3863 Replies:4 FollowUps:13
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My el cheapo 12 pin trailer plug worked well for a couple of years, then ran hot and with reduced current.
Is there a make which has pins with better material or coatings such as silver or gold? I don't mind paying a premium for longevity and efficiency. Maximum current to larger pins is 10 amps to frig & 7 amps to battery. Contact cleaning sprays worked for about 10 times, but not now. Any advice will be appreciated.
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Reply By: Ross M - Saturday, Apr 19, 2014 at 19:12

Saturday, Apr 19, 2014 at 19:12
If you are trying to pass more than a few amps ie brake current or lights only current through the plug it will fail. Most others will too.
For any heavier current, use Anderson plugs, two separate ones if needed, for the fridge and battery supply.

It is fairly useless to try and run a fridge through a trailer plug, same for battery charge current which can initially be quite high amp flow.
Both the fridge and the battery require heavy wire to reduce voltage drop VD to a minimum for best performance and no fry ups of equipment.
AnswerID: 530879

Follow Up By: martycon - Saturday, Apr 19, 2014 at 19:18

Saturday, Apr 19, 2014 at 19:18
Thanks Ross, I was hopeing not to hear that.
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Follow Up By: Member - Wozikev - Monday, Apr 21, 2014 at 10:36

Monday, Apr 21, 2014 at 10:36
Spot on Ross. I run two Anderson plugs with 8 B&S wire, one to the fridge and the other to my Redarc BMS alongside the two 100 ah AGM batteries in the van. The 7 pin trailer plug does only brakes and rear and side lighting etc on the van. It all works a treat.
Cheers ........................... Kev.
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Reply By: Member - Keith C (NSW) - Saturday, Apr 19, 2014 at 19:28

Saturday, Apr 19, 2014 at 19:28
Hi Marty, Sometimes you can widen the pins with a small knife or s/driver, they make better contact, cleaning also helps. these plugs should only used for trailer lights,Ross is spot on with battery & frig wiring
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Follow Up By: martycon - Saturday, Apr 19, 2014 at 19:48

Saturday, Apr 19, 2014 at 19:48
Thanks Keith, looks like I must bite the bullet.
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Reply By: Nomadic Navara - Saturday, Apr 19, 2014 at 22:58

Saturday, Apr 19, 2014 at 22:58
I have found Narva products to be of reasonable quality. There is a selection of flat plugs in this link. I am using this socket on my D40 link.

You will note that the smal pins are rated at 15 A and the larger ones at 35 A. I have had my 25 A DC to DC charger running through pin 8 and the fridge running through pin 9 without any problem.

I would steer clear of the stuff BFC are flogging.
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AnswerID: 530898

Follow Up By: martycon - Sunday, Apr 20, 2014 at 09:47

Sunday, Apr 20, 2014 at 09:47
Thank you Peter, I may persist in using 12 pin but using the Narva product, and spray clean terminals EVERY time I connect.
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Follow Up By: Aussi Traveller - Sunday, Apr 20, 2014 at 09:53

Sunday, Apr 20, 2014 at 09:53
Is the risk of a fire worth not doing it properly and persisting with the wrong plug. ???

Just sayin

Phil
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Follow Up By: Nomadic Navara - Sunday, Apr 20, 2014 at 13:42

Sunday, Apr 20, 2014 at 13:42
Who said they are the wrong plug. There are thousands of them out there working satisfactorily. They are like any other equipment. You just need to treat them with a little respect and give them a little maintenance. I just run a thin knife blade a little down each male caontact before every long trip. I have no problems with mine.

I suppose we need these opinionated types on the forum to add a little spice to it.
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Follow Up By: The Bantam - Sunday, Apr 20, 2014 at 17:35

Sunday, Apr 20, 2014 at 17:35
peter the flat trailer plug is a horrible thing...they are just trash

I work will all sorts of plugs for a living and I know of no high reliability plug of any type that has a split male pin...this is the fundamental problem.

All the good plugs rely on the female portion for their contact pressure.

The split male pin is neither the shape, form or material to retain sufficient spring tension to maitain good contact pressure.

If you prise those crappy pins open on time too meny they slpit then are completly useless.

you should not have to adjust the contacts on a plug every trip.....I have a 30 year old genuine utilux on one of my trailers and the only attention it has ever had to hose the mud out of the contacts and a squirt of contact spray every coupl of years.

everything about the flat trailer plug from its thermoplastic housing to is piddly little screws is just horrible.

I have had to work with these things and so many of them the screws are stripped straight out of the box..and that is the "good brand"

I don't know why they are so popular in the south because QLD is very much a 7 pin utilux market

The ony reason we use em up here is to mate with somthing that is already there......or because a southern wants one.


sorry met they are just trash.

cheers
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Reply By: The Bantam - Sunday, Apr 20, 2014 at 11:59

Sunday, Apr 20, 2014 at 11:59
Marty mate, in my opinion the flat trailer plugs, both 7 pin and 12 pin are fundamentally flawed in many ways.

The way the contacts are designed
the way the contacts are mounted in the plug
the way wires are connected into the contacts including how poorly the screws are fitted to the contacts
and I could go on
There are just a cheap and nasty design from start to finish.

There is very little any manufacturer could do to improve the plastic rectangular trailer plug....they are just junk.

They simply do not compare to the proven utilux style 7 pin round, of which there are several competently made items on the market.

The second flawed notion is carrying electrical supply in the same plug used to carry mandatory lighting.

There requirements of the two are just so different...the current demands of stop, indicator and brake lights are quite modest and the wire sizes are in general relativly small.

Where as the demands of electrical supply for caravans and the like are at least five to ten times greater and if they are to travel the distances require very much heavier cables
typical ( old incandessant) brake light circuit is 3.5 amps.....typical 3 way fridge is 15 amps.
If you want to charge a battery you need to be starting arround 20 amps and 50 is not unreasonable.

You are far better off with a utilux style 7 pin round trailer plug for your lights & brakes and an anderson or something else as your electrical supply.

cheers


AnswerID: 530917

Follow Up By: Member - Phil G (SA) - Sunday, Apr 20, 2014 at 15:49

Sunday, Apr 20, 2014 at 15:49
I agree. The large round 7 pin has every terminal rated at 30 amps and takes 6mm auto cable, then add a 50 amp anderson plug (which self-clean better than the 12 pin), and the bonus is that you'll have a decent earth on each.
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FollowupID: 813907

Follow Up By: The Bantam - Sunday, Apr 20, 2014 at 15:59

Sunday, Apr 20, 2014 at 15:59
If you are just running the normal mandatory trailer lights and maybe electric brakes the small round 7 pin utilux plug is fine with a per pin rating of 15 amps....I have seen the used and abused for decades and still working fine.

The larger round plug is generally only needed in heavy transport.

But both are a far better designed plug than the flat plugs.

cheers

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Follow Up By: Member - Phil G (SA) - Sunday, Apr 20, 2014 at 16:13

Sunday, Apr 20, 2014 at 16:13
Much easier to fit the wires into a large round plug than the small round plug. And you only have one earth - may as well be a good one. The large round is still the most common plug used in SA.
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Follow Up By: martycon - Sunday, Apr 20, 2014 at 17:12

Sunday, Apr 20, 2014 at 17:12
What a wealth of experience with all combined. Thank you Ross, Keith, Peter, Bantam, and Phil. Round Utilux & Anderson plug sounds like good advice to me.
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Follow Up By: Peter T9 - Sunday, Apr 20, 2014 at 18:09

Sunday, Apr 20, 2014 at 18:09
It is fairly common to use more than one terminal for each of the earth and live wires in the flat twelve pin plugs (ie a small wire connecting two adjacent terminals together). Britax is a good quality plug.

I personally use an Anderson plug.
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Follow Up By: The Bantam - Sunday, Apr 20, 2014 at 22:36

Sunday, Apr 20, 2014 at 22:36
Its interesting that diferent plugs are strongly favoured in different parts of the country.

I actually don't known anybody up here that has other than a small 7 pin round on their trailer.

As for using multiple pins for certain purposes...um not a good idea.

There are published standard pin outs for the approved trailer connectors, we should all adhere to those standard pinouts.

Otherwise there is no point having standardised connectors.

Britax do make a pretty damn good coppy of the original metal bodied small 7 utilux plug.

from what I understand utilud dropped the design a long time ago in favour of their all plastic version and their realy beefy current metal case version.

cheers
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