Look how to wire up a trailer and caravan socket.

Trailer Wiring Codes

12N – Sockets are used on trailers and caravans etc to connect and extend the obligatory road lights (indicators, brake, fog and side lights).

12S – Sockets are used for auxiliary systems (fridge, battery charge, power feed etc.). These Sockets are not fitted as standard on trailers but are commonly used on caravans.

Both the above sockets are similar in appearance, but differ with the gender of the pins, 12N having 4 male pins while the 12S having 5 male pins, with the centre pin denoting the difference between both sockets. The difference ensures that connectors cannot be connected to the wrong socket.

Pin Connections 12N:

12N – (SEE ABOVE) The diagram shows the front layout, and the rear connection numbering (side the wires are terminated).

12N connectors are normally coloured black. Pins 2, 5 and 7 in the plug are female, others are male.

Pin Connections 12S:

12S – (SEE ABOVE) The diagram shows the front layout, and the rear connection numbering (side the wires are terminated).

12S connectors are normally coloured white. Pins 2 and 5 in the plug are female, others are male.

Check the wiring instructions that will accompany the plug, if unsure ask your local caravan or trailer dealer.

The wires are generally terminated by screw terminals, be careful that no stray cable strands that could create a short circuit. When complete assemble the plug and ensure cable strain relief it fully tightened and that the gland has also been tightened to ensure water resistance.

NOTE: Number plate light(s) wired to side light(s).

Over 1.3m wide, must have rear fog light.
Over 1.6m wide, must have front marker lights.
Over 6m length, must have side marker lights.