That's unfortunate Andy although concurring with guidelines. With HID as a technology pre-dating LED headlamps and no specific guidelines for the latter to MOT testers at the moment, it seems only a matter of time before such guidance becomes available. It also seems a fair assumption that the same rulings will apply though as per these present ones redacted from current aftermarket HID guidelines:
The legal situation
The Road Vehicle Lighting Regulations 1989 regulate the situation in the UK. Under these regulations, HID/Gas Discharge/Xenon headlamps are not mentioned and therefore they are not permitted according to the strict letter of the law.
However new vehicles have HID headlamps. This is because they comply with European type approval regulations. The UK cannot refuse to register a vehicle with a European type approval. These approvals relate to ECE Regulation 98 (for the HID headlamps which are tested on a rig in a laboratory) and ECE Regulation 48 (lighting installation on the vehicle).
For the after-market, a used vehicle cannot obtain type approval because this only applies to new vehicles. However DfT does not think it reasonable simply to ban HID in the aftermarket. Instead the department makes analogies with new vehicles. It seems reasonable to require HID in the after-market to meet the same safety standards as those for new vehicles. The same level of safety should apply.
HID headlamp unit requirements
Therefore a HID headlamp unit sold in the aftermarket should:
be type approved to ECE Regulation 98 as a component
when fitted to the vehicle should enable ECE Regulation 48 to be complied with (although no government inspection will take place)
comply with RVLR as far as “use” is concerned
In practice this means:
the headlamp unit (outer lens, reflector, bulb) shall be type approved to ECE 98 and be “e-marked” to demonstrate this. That can only be done by the headlamp supplier - Hella, Valeo, etc - who must test the headlamp in an independent laboratory
once fitted to the vehicle it must have headlamp cleaning and self-levelling (which can be for the headlamp or can be in the vehicle suspension - some expensive estate cars have “self-levelling suspension” and that is adequate). Also the dipped beam must stay on with the main beam
the headlamp must be maintained in good working order, kept clean, and aligned/adjusted correctly in the same way as any other headlamp
Under the Road Traffic Act 1988 it is an offence to supply, fit or use vehicle parts which are not legal.
In summary: it is not permitted to convert an existing halogen headlamp unit for use with HID bulbs. The entire headlamp unit must be replaced with one designed and approved for use with HID bulbs and it must be installed in accordance with the rules stated above.
