12S plug

[ThePlotter]

I have just had my two year old Abbey Vogue serviced and it needed the 12s plug changed as the plastic around the centre pin was showing signs of melting,I have been aware of this as this is the third plug ( on two vans ) in three years ,last time it needed the socket on the car as well.I make a point of using a small screw driver to keep the slot in the pin open but it can still happen.

It of course has only been a problem since the use of the various pins was changed a while ago,but the real cause is that the centre pin is longer than the rest but the socket it goes into isn't,can anybody explain why Hella and the like make the plugs like this,I can see no logic in the design.

 

[rob_jax]

Tony,

The 12S connector is a good example of using something for a new purpose for which it wasn't designed.

For many years, only the 12N connector was used but as more caravan electrical systems and extra car lights were added, then the need for a supplementary connector arose.

The 12S central pin is designated as the earth return for the fridge and needs to handle 20+ amps, it is also proud of the surround to act as a location pin - knock it and you get a bad connection - melting the plastic.

The copper / brass pins / sockets are susceptible to corrosion - increasing resistance and melting the plastic.

And the physical connection between 12N+S plug and socket is a push and hope job - no physical joint - and this needs to pass 20 amps.

Temporary Fix: You can use one of the unused 12S pins to run a separate earth (return) and split the load.

Of course there is a properly designed connector - the European 13 pin connector which is an ISO international standard - it is designed to handle the high currents, it's water proof, it's a twist-lock making sure the pins and sockets are in good contact, and the pins are electro-plated to resist European winters.

For the past five years we've used the 13 pin Euro connector - partly because our Eriba is fitted with the 13 pin plug as standard and the detachable tow-bar on my C270 has a 13 pin swing-away connector that folds up under the bumper when not in use. Result - no problems, no cleaning, no worries for five years.

Permanent Fix:

Swap the old 12N+S plug and socket for a single 13 pin ISO / Euro connector.

Why hasn't it taken over in the UK? Entrenched, legacy support for the old 12N+S, cheap for the caravan manufacturer, resistance to change - fair number of people worry about every and anything.

Robert