Information & images courtesy of Witter Towbars Ltd

Should I have a 12N 7 pin electric connector?

This is the most common and cost effective type of connector currently used in the UK. It will fulfil all Normal towing requirements under UK law and can be used with lighting boards, cycle carriers, caravans, trailers and horseboxes. In fact anything you can connect to a towbar.

Should I have a 12N 12S, 7 pin double electric connector?

This consistsof a Normal connector as above and a similar extra Supplimentary connector that can supply a caravan, horsebox or tipper trailer with a switched and permanent 12 volt power supply, extra earth connections, and a reverse light facility.
A 12S socket is only required if you wish to charge the battery and power the fridge when travelling.  Having both connectors on the towbar can be bulky and unsightly, especially when fitted to a detachable towbar.

Should I have an ISO 13 pin electric connector?

This is a single connector of similar size to that of a 12N connector but it contains both 12N and 12S functions in one. It is a waterproof connection with a unique twist lock system for safe reliable contact.
The socket is smart and discreet, ideal for towbars with a swing away socket plate. The cost is higher than having separate 7 pin sockets. However, all caravans manufactured in the UK from 2008 will have a 13 pin plug fitted as standard, this will soon become the norm on towbar installations.

Should I have a WeSt 13 pin electric connector?

This is a clever socket that looks like a normal 12N socket and compatible with a standard 12N plug as found on trailers and light boards. It may also be used as a 12N/12S connector when used with a WeSt plug on your caravan. It has the standard 12N pins with 6 extra smaller pins around the outside to provide the 12S functions.
This type of socket is rarely, if ever, seen in the UK.