UK Trailer Plug and Socket Guide – 7 pin, 8 pin and 13 pin explained
When fitting a towbar or towing a trailer, caravan or bike rack, the electrical connection is just as important as the towbar itself. Every trailer or accessory needs power for its road lights to ensure safety in traffic. That power comes through a plug and socket system that connects your vehicle to what you are towing.
The three most common systems in the UK are 7 pin, 8 pin and 13 pin. Each has different wiring layouts, features and uses. Choosing the right one depends on what you tow: from simple utility trailers and cycle carriers through to modern caravans with on-board power. This guide explains the differences and shows the wiring diagrams so you know which option is right for your setup.
7 pin trailer plugs (12N)
The 7 pin plug, also called 12N, is the most widely used system for basic towing electrics in the UK. It powers the essential road lights: tail lamps, brake lights, indicators and fog lamp. It does not include a reverse light or 12V power feeds.
What 7 pin plugs are used for
- Small trailers for domestic and light commercial use
- Trailer light boards and cycle carriers
- Older horseboxes and boat trailers
- Some caravans when paired with a second 7 pin 12S power socket
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8 pin trailer plugs
The 8 pin system is less common but is used on some specialist trailers such as horseboxes, plant trailers and certain continental imports. The eighth pin usually powers a reverse light or auxiliary feed, making it more versatile than 7 pin while still simple. Wiring layouts can vary, so always check before replacing.
What 8 pin plugs are used for
- Horseboxes requiring reverse lighting
- Imported trailers with an extra function beyond 7 pin
- Specialist trailers such as plant and agricultural equipment
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13 pin trailer plugs
The 13 pin system is the modern UK and European standard, combining all road lights plus reverse, along with permanent and switched 12V power. The plug design is waterproof, twist-locking and more reliable for frequent use. It has replaced the older twin 7 pin system (12N and 12S) on caravans.
What 13 pin plugs are used for
- Modern caravans with reverse lights, leisure battery charging and fridge power
- Larger trailers with reverse lighting and auxiliary circuits
- European imports which all use the 13 pin standard
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Quick comparison: 7 pin vs 8 pin vs 13 pin
| Feature | 7 pin | 8 pin | 13 pin |
|---|---|---|---|
| Road lights | Yes | Yes | Yes |
| Reverse light | No | Yes (extra pin) | Yes |
| 12V power feeds | No | Occasional use | Permanent + switched |
| Waterproof design | No | No | Yes (sealed twist-lock) |
| Locking mechanism | Push fit only | Push fit only | Secure twist lock |
| Adapters available | Yes (7 to 13) | Limited | Yes (13 to 7) |
| Typical use | Trailers, light boards | Horseboxes, specialist trailers | Caravans, modern trailers |
FAQs
Is a 7 pin socket still legal in the UK?
Yes. A 7 pin socket is perfectly legal for basic trailers and light boards. However, if your trailer has a reverse lamp or you are towing a caravan, you will need a 13 pin or an additional socket to meet road requirements.
What is the difference between 12N and 12S?
12N is the standard 7 pin socket for lighting functions. 12S is a second 7 pin socket used in the past on caravans to supply power for fridges and charging. Modern caravans now use a single 13 pin socket instead of twin 7 pins.
Can I tow a caravan with just 7 pin?
No, not safely. Caravans require 13 pin electrics to power reverse lights, internal systems, and charging. You can use adapters for short-term use, but a proper 13 pin fit is strongly recommended.
Can I use an adapter between 7 pin and 13 pin?
Yes. Adapters exist both ways: 7-to-13 and 13-to-7. They are useful if you occasionally tow a caravan or trailer with a different plug, but they are not as reliable as having the correct socket fitted permanently.
Why do caravans use 13 pin?
Caravans need more than just lighting. They require reverse lamps, power for fridges, and charging for leisure batteries. The 13 pin system provides all of this in a single waterproof connector, which is why it has become the UK and EU standard.
Need help choosing or fitting?
At GT Towing we supply and fit all types of towbar electrics, from basic 7 pin plugs through to full 13 pin dedicated kits. Our team will ensure your electrics match your vehicle and towing needs, so you can drive away with confidence.
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