Pin Burnout

‘Pin Burnout’ as it is referred to, is a phenomenon which occurred when the new wiring layouts were introduced by the caravan manufacturers in late 1990’s. 

It is required that a separate earth be provided for  the 12volt fridge feed. This is provided now on pin 7, the centre pin on a 12S socket.  Prior to 1999, this pin served no function although it may have been wired up.

There has been NO reported incidents of pin burnout with the 13 pin socket system.

What became apparent during connection and in transit, that the contact between the centre pin on the trailer plug and 12S socket would heat up and start to melt the area around the pin.  This was noted by the black discolouration.  There are 2 possible causes for this problem.

1) That the wire size is not sufficient capacity either in the caravan 7 core cable or that fitted in the car, to carry a return earth for the high consumption fridges. Or,

2) As the centre pin on the plug is raised slightly above the others, the actual insertion of the plug into the socket is causing a break in the contact between the pin and it’s receiver socket.  This is caused by the ‘wiggling’ action of the plug whilst being inserted.  This action, then squashes the pins together and the point of contact is greatly reduced causing an ‘Arcing’ effect.