3 pin 12v connector/receptacle question

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Moderator Emeritus
Sep 25, 2008
Vessel Name
"Emily Anne"
Vessel Make
2001 Island Gypsy 32 Europa (Hull #146)
Our "new" 2001 chinese built boat has a couple of these receptacles mounted in the dash at the lower and upper helms which are not at all useful for cell phone chargers, spot lights, etc that require a cigarette lighter receptacle. Acutally, I can't think of any appliance that might use them. The PO made up a couple of jury rigged pigtail type adapters that convert them to 2 wire cigarette lighter receptacles (bypassing the "fat" pin of the 3 pins) but they are not a very elegant solution are pretty fragile and have to be connected each time you want to use them unless you leave them dangling.

I'd like to just pull these 3 pin connectors out and replace them with proper cig lighter receptacles but I am a bit of an electrical boob.

Does anyone know what are the three wires on 3 pin connectors. Pos, neg and ground? Would I just tape off the wire that is connected to the "fat" pin as the PO did with the pigtail adapters?
The common cigarette lighter plugs are mostly pure CRAP.

Few will pass even 5A with out getting warm.

A better ?( for us) solution is to go to Home Depot and purchase the heavier duty 20A 220V plugs , and sockets. They look just like 120V but the plug angles are different.

AS most small boats never have 220 for portable appliances the ability to actually carry real 20A electric and be polarized , so no reverse polarity hassles is great.

Not a cheap as RV stuff , but long lasting and very safe.

David, I have not seen 12 volt with 3 wires so can only assume the earth ground is tied in. The wires for the outlets should be color coded. If the earth ground is tied in, green, I would not just cut these since you may be breaking the bonding system. You can simply reconnect them to themselves. Your other 2 wires should be red and black or yellow, yellow being the new acceptance for 12 volt ground. They might be the proper color with a different color trace. If not color coded that way a volt meter will tell you which is positive and which is negative. There are some excellent 12 volt cigarette style outlets you can install, but don't buy the cheapy ones sold by Worst Marine, etc.
Thanks for the replies.

Capn Chuck: Unfortunately I cannot use a voltmeter right now as the batteries are out of the boat until spring.

I did go onto the boat today and looked at the wiring to the 3 pin receptacle. Confused me even more. Of the 2 "small" pins, one is a red solid wire and the other is a black solid wire. The wire to the "fat" plug is also red but is a heavier gauge and multi-strand wire. Saw no tracers or codes on the wires.

Guru: I am trying to avoid having to "replug" each of the appliances I want to use in the 12v sockets as I may want to use them in my car as well.
I think surveyors would go nuts over using 240V outlets for 12V wiring.
Solid strand wire is a no-no on boats as far as surveys and insurance companies are concerned. If this is something a PO has done it can be anything. But without being tested for voltage any help will be pure speculation. Chuck
"I think surveyors would go nuts over using 240V outlets for 12V wiring."

Not with no 240V aboard , and it has been the savior of the off grid folks for at least 4 decades.

A 12V label might help the simple minded.

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