Three pin plug wiring

Why use a 3 pin plug on the deck of a boat.

I would not have a 240 Vac outlet on the deck of my boat all my 24- Vac are inside in a protected environment

I use 2 pin socks similar to the one picture and it is still only one way round so can ve used for 12 Vcd as I have done.

The 2 pin have different size pins so can only be fitted one way round.

I have a 2 pin plug on my movable solar panel for charging my engine start battery
 
rogerthebodger said:
Why use a 3 pin plug on the deck of a boat.

I would not have a 240 Vac outlet on the deck of my boat all my 24- Vac are inside in a protected environment

I use 2 pin socks similar to the one picture and it is still only one way round so can ve used for 12 Vcd as I have done.

The 2 pin have different size pins so can only be fitted one way round.

I have a 2 pin plug on my movable solar panel for charging my engine start battery
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As I understand it he has a 3 pin screw down deck plug for a combined deck and steaming light fitting (needing 2 separate 12v feeds and a shared 0v return), not a 230v inlet.
 
rogerthebodger said:
Give the guy a break he is a new user of the forum and found the thread using Google

His reply "So it doesn't matter which wire is connected to which pin (after the earth pin is connected)"

seems to relate to main referring to the earth pin can differ depending on the standards in his location.

In the UK it does matter which pin which wire is connected to in the 3-pin plug.
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Actually I did see the date, but you see, people did answer!
I wired the plug and all is good. What I meant is this: the large pin is of course the earth. Testing with the multimeter the other two act as the positives for two different lights. It determines which light turns on for each of two switches on the panel. Newbie here! Thanks!
 
Dellquay13 said:
It’s probably one of these deck plugs, low voltage about 5a max, or maybe a plastic variant.
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As mentioned earlier one of the pins is larger to key it in one way only. Some people use that large pin as the 0v (or negative) pin, and use the other two pins for each of the 12v sends, but there isn’t a electrical ‘standard’ or officially right way to wire it.
If you are using 230v mains flex, it would be good practice to cover the brown, blue and green/yellow inner insulations with black and red insulation tape or sleeving, to show which is 0v and 12v for future reference.
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If you want to check I think you may find that these LPA (Niphan) plugs and sockets are mains rated, not just low voltage. The big pin is an EARTH. and as has been said is locked with the grub screw through the body of the fitting. If you use it as a common -ve return on a 12 or 24 volt dc system fine. just be aware that the body will be connected to the negative. I have spent a good deal of my working life using these on d.c and a.c @12,24, 115 & 220 volts. I am not a great fan, they do tend to corrode and are not as waterproof, or resistant to salt atmosphere, as you may think 🙄
 
Alex_Blackwood said:
If you want to check I think you may find that these LPA (Niphan) plugs and sockets are mains rated, not just low voltage. The big pin is an EARTH. and as has been said is locked with the grub screw through the body of the fitting. If you use it as a common -ve return on a 12 or 24 volt dc system fine. just be aware that the body will be connected to the negative. I have spent a good deal of my working life using these on d.c and a.c @12,24, 115 & 220 volts. I am not a great fan, they do tend to corrode and are not as waterproof, or resistant to salt atmosphere, as you may think 🙄
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The issue I have with the 2 pin plug/socket is that the pins are simply brass with no corrosion protection.

Any corrosion on the pins will cause resistance and loss of voltage and with low voltage can cause heating due to increase current or in an extreme case the corrosion can cause an insulation that low voltage cannot break through causing an open circuit
 
Alex_Blackwood said:
If you want to check I think you may find that these LPA (Niphan) plugs and sockets are mains rated, not just low voltage. The big pin is an EARTH. and as has been said is locked with the grub screw through the body of the fitting. If you use it as a common -ve return on a 12 or 24 volt dc system fine. just be aware that the body will be connected to the negative. I have spent a good deal of my working life using these on d.c and a.c @12,24, 115 & 220 volts. I am not a great fan, they do tend to corrode and are not as waterproof, or resistant to salt atmosphere, as you may think 🙄
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on mine, as in the picture in post #20, there is no continuity between the body locking grub screw and any of the pins.
 
Plum said:
on mine, as in the picture in post #20, there is no continuity between the body locking grub screw and any of the pins.
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OK. I appreciate there are variants. Guess you have to take as you find.
Edit:- Memory is a funny thing and it is now over twenty years since I had one apart. However, I do believe that one version had a brass threaded insert in the plastic body and another just a hole that went through to the pin :unsure:
Main point I was making was that it should not be assumed that these plugs were all low voltage. They could have mains on them.
 
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Alex_Blackwood said:
If you want to check I think you may find that these LPA (Niphan) plugs and sockets are mains rated, not just low voltage. The big pin is an EARTH. and as has been said is locked with the grub screw through the body of the fitting. If you use it as a common -ve return on a 12 or 24 volt dc system fine. just be aware that the body will be connected to the negative. I have spent a good deal of my working life using these on d.c and a.c @12,24, 115 & 220 volts. I am not a great fan, they do tend to corrode and are not as waterproof, or resistant to salt atmosphere, as you may think 🙄
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Those 3 pin deck sockets wouldn’t be my choice for 230v, if they are indeed certified for that.
The brass inserts that grip the plug pins are only a millimetre or so recessed and aren’t very well protected against anything getting inside. At least a standard UK outlet has the little plastic doors on the live and neutral that stop anything straying inside when the socket isn’t in use.
 
Dellquay13 said:
Those 3 pin deck sockets wouldn’t be my choice for 230v, if they are indeed certified for that.
The brass inserts that grip the plug pins are only a millimetre or so recessed and aren’t very well protected against anything getting inside. At least a standard UK outlet has the little plastic doors on the live and neutral that stop anything straying inside when the socket isn’t in use.
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As the OP 14 years ago, I can confirm it was 12v only... ;)
 
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