Hey Steve,
Think that's a common fallacy:
Fact sheet from D of T:
http://www2.dft.gov.uk/pgr/roads/vehicl ... aravan.pdf
text below
All trailers are permitted to have electric brakes regardless of whether they are from America or from somewhere else. Regulations specify that the transmission method by which the signal is used to apply the brakes may be mechanical, hydraulic, pneumatic, electric or mixed. [UNECE Regulation 13, paragraph 2.5. / EC Directive 98/12/EC, paragraph 1.5.]
Differences between American caravans and trailers, and European regulations...
1. Operating brakes
It is common on American caravans/trailers with electric brakes to have an electrical device mounted in the towing vehicle which the driver operates manually to apply the brakes of the trailer independent to the brakes on the tow vehicle. This is prohibited in Europe where the regulations demand that the service braking system must be applied without the driver removing his hands from the steering control. [UNECE Regulation 13, paragraph 5.1.2.1. / EC Directive 98/12/EC, paragraph 2.1.2.1.]
2. Mounting sensor devices
Alternatively, American caravans/trailers with electric brakes can have an electrical device mounted in the towing vehicle which senses deceleration in the towing vehicle and transmits a signal to the caravan/trailer braking system to operate the brakes. European requirements demand that this type of device must be mounted on the caravan/trailer.
3. Supply of electricity for electrical braking systems
The electrical energy required for the electrical braking system must be supplied to the trailer by the towing vehicle. If there is a battery on the trailer which is fed by the power supply unit of the towing vehicle, the power from the battery must be disconnected during application of the service braking system.
4. Time delays
Some American caravans/trailers rely on a signal from the towing vehicle stop lamps to initiate braking on the caravans/trailers. Owners of such vehicles need to be aware that the system may not meet the requirement for brake response time. European regulations demand that the time delay between the time at which the driver applies the brakes and the time at which the braking force on the least favourably placed axle reaches the level corresponding to the prescribed brake performance must not exceed 0.6 seconds. This could be difficult to achieve on systems that have to wait for the stop lamps to operate before the electronic control unit is activated and the system produces the prescribed brake level.
5. Parking brakes
American caravans/trailers do not always have a parking brake. European requirements demand that a caravan/trailer must be fitted with a parking brake that is capable of holding the vehicle stationary on an 18 per cent up or down gradient. Also, the working parts must be held in the locked position by a purely mechanical device.
6. Braking mechanisms
American caravans/trailers do not always have brakes on all wheels, and it is common for a two axle trailer to have brakes on only one axle. This is prohibited in Europe where regulations demand that each individual wheel must brake.
Caravans and trailers fitted with a braking system are required to be stopped automatically if the coupling separates while the trailer is in motion.
7. Override coupling
Caravans and trailers with an override coupling must be equipped with an automatic device that permits the combination to be reversed without the brakes generating a braking force.
American “5th wheel” type caravans are classified as semi trailers and, as such cannot use an inertia (override) type braking system. The operation of the towing vehicle’s braking system must directly operate the brakes on the trailer and electrically controlled systems are permitted.
8. Coupling (ball hitch) dimensions
The American ball hitch diameter is usually 2 inches whereas the European (UK) is 50mm, therefore the trailer coupling may need changing to be compatible with the 50mm ball.
UK Legislation
Current UK legislation demands compliance with Directive 71/3 20/EEC including amendments up to and including Directive 98/ 12/EC. C&U Regulation 15 also recognises United Nations ECE Regulation 13 up to and including the 09 series of amendments.
Additional Information
In the UK a caravan or trailer towed behind a motor vehicle of less than 3500kg Gross Vehicle Weight is restricted to a maximum width of 2.55 metres .
