7 Pin plug grey S type:

The 7 pin supplementary grey S type plug was designed for tow bar connection for supplementary internal working of a caravan or trailer tent.

The normal 7 pin plug does not have extra connections to run extra power so an additional plug was designed.

The S plug carries 12 volt electricity for the fridge and for some internal 12 volt appliances.

The fridge connection should be wired by a motor electrician as it carries a heavy load and also wired so that it cannot be inadvertently left drawing power.

The plug should be replaced if it becomes damaged or corroded.