There's a lot of confusing and contradictory information about aftermarket high-intensity discharge - or “HID” - kits and whether or not they’re legal on road-going cars in the UK.

As well as needing to be legal in case you are stopped by the police, you also need to be able to pass an MOT test.

This guide pulls together all the information I could find online from sources such as the official MOT test handbook published by VOSA, the European regulations which are used to make up UK law, and information from the Department for Transport.

The bottom line, as far as I can see, is this:

You can fit an aftermarket HID kit to a UK vehicle, and as long as the beam pattern is correct, the light is predominantly white or yellow-white, there is no glare for other road users, and the light passes all the standard MOT test checks such as being secure and pointing in the right direction, then you should be able to pass an MOT and not break the law.

 

BUT, this doesn't necessarily mean you will be road legal as you will be driving a car which has parts which have been modified and these parts won't have been subjected to the approval processes which manufacturers have to go through.

 

So, even if you pass an MOT and don't attract attention from the police, you may still find yourself in trouble if you crash, or cause somebody else to crash, and it is discovered that you've made modifications to your vehicle.

 

And, of course, you may invalidate your insurance if you perform a modification which you haven't told them about.

So, not to put too fine a point on it, you're on your own, and your decisions are your own.

That said, here's what I've found out; if you think you can improve this guide, please drop me a message so I can fix it - thanks!

This page was up-to-date as of March 2015.

• Important: please read this bit!
• What does the law say?
• What are the MOT test rules?
• The Department for Transport’s view
• Bad news for drivers in Northern Ireland, though
• The bottom line from VOSA
• The law on aftermarket HID and LED lighting in the UK, in detail, with links and references
  • Headlight washers and automatic levelling
  • Information on adjusting headlight aim
  • A quick note about manual headlight adjusters
  • Switching between dip and main beams
• The MOT test rules from VOSA, in detail, with links and references
  • What the MOT handbook says about HID and LED headlamps
  • HID headlights must turn on straight away
  • HID headlights must be mainly yellow or white
  • Lastly, the lights should match each other’s colour
  • Beam patterns
  • Headlight aim
• More about that Department for Transport document
  • What the article says
• Comments and corrections

Lastly, but most importantly - please read this bit!

A quick note of caution and a disclaimer: as is the case with anything you read on the internet, this is only a best-guess at best, and you shouldn’t rely on what you read here as evidence that your car will be road legal. There isn’t an easy way to be sure that you are legal, and a lot of the legal wording is vague enough that a determined MOT tester, law enforcement officer or judge may be able to give you a very hard time. So please, don’t take this as gospel, do your own reading, and seek legal advice if you find yourself in trouble - I’m just providing the information I can find in one place.

What does the law say?

In a nutshell:

1. EU law says that HID headlights which emit more than 2,000 lumens of light, and all LED headlights, must be fitted with washers and self-levelling,
2. But it’s not possible to accurately measure total light output either at the roadside, or in an MOT station,
3. So if it can’t be proven that your lights emit more than 2,000 lumens of light, this regulation almost certainly doesn’t apply to you,
4. But, your lights must be aimed correctly and have the right beam pattern on dip and main,
5. If you have a manual headlight adjuster, the highest angle the headlights can be set to must not be higher than the rules allow,
6. Lastly, HID dipped beams must stay on while your main beam is on.

Read a detailed explanation of these points here.

What are the MOT test rules?

In a nutshell:

1. You don’t need headlight washers or self-levelling, but if your car has them fitted, they must work - there are a small number of cars in the UK, including older Renault Meganes and at least one Mitsubishi Evo, which were fitted with HIDs but no washers or self-levelling. These cars are legal in the UK, but see the note about Northern Ireland’s DVA below,
2. Your headlights must work immediately when turned on, so you need high quality ballasts and bulbs which ignite straight away, even when hot - i.e. you must be able to flick the lights off and back on again straight away,
3. The light must be mainly white or yellow - in practice, this means kits up to 5,000K colour temperature should be fine (as HID bulbs get older, they get more blue, so high-mileage standard lamps can be around 5,000K). Kits over 5,000K are more likely to attract attention from the police, or be a cause for an MOT failure,
4. Your dip and main beam pattern must conform to the regulations, which means a good cut-off and no upwards glare on dip, and a focused high beam,
5. Your dip beam pattern must be aimed downwards at the correct angle.

You can read a detailed explanation of these points here.

The Department for Transport’s view

In a nutshell:

The Department for Transport published a document in 2010, snappily titled “Aftermarket HID headlamps”, which says the following, but remember - this is not The Law, and therefore does not carry any sway, so if somebody refers you to this document or a variation of it, you can rest assured that the information above from ECE Regulation 48 and VOSA supersedes this.

There is even a paragraph in this article which says that this is the opinion of the DfT and not the law: “NOTE: The information in this document is a summary of DfT’s understanding of what the law requires. However, ultimately the interpretation of the law is a matter for the courts based on individual facts of any particular case. You are therefore advised to consult the relevant legislation and, if necessary, seek independent advice. "

Interestingly enough though, the article says “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.” In practice, this implies quite clearly that if you fit a projector designed for HID lamps into a reflector headlight so that the resulting beam pattern is correct, you won’t be in breach of the DfT’s guidelines on aftermarket HIDs.

More on this article by the DfT, below.

Bad news for drivers in Northern Ireland, though

Northern Ireland’s DVA says that cars “must” have washers and self-levelling when HIDs are fitted (compared to VOSA’s wording which says cars “may” have washers and self-levelling).

This has been cited as the cause of at least one MOT failure on a car which had HIDs from the factory, but no washers or self-levelling fitted, according to this report by Auto Express.

The bottom line from VOSA

VOSA wrote the following in response to a Freedom of Information act request (which can be viewed here):

1. 6) The [MOT] test in Great Britain is required to comply with the European Framework Directive on periodic technical inspection. In this regard the annual test is to be amended in April this year to include the satisfactory operation of automatic levelling and washing systems where these are fitted. However, these systems are not mandatory for all vehicles fitted with HID lamps as it is dependant on light output and/or suspension movement. As it is not possible for a tester to determine at the time of test (annual or roadside) whether these components are required, there is no reason for rejection, either in the directive or the amended manual.
2.  
3. 7) In respect of lamp colour, HID headlamps are considerably brighter than conventional headlamps and tend to produce a whiter light, although they may appear to have a blue tint. This is perfectly acceptable provided the bulbs are ‘E’ marked, but it is not possible to determine this at annual test, as dismantling is not allowed. It is only where a headlamp is clearly an incorrect colour where it will fail.
4.  
5. 8) Satisfactory operation of the dipped and main beam headlamps is also part of the test and includes switching between the two functions. Therefore, if a headlamp does not operate immediately when switched between dipped and main beams, or vice versa, then this would result in a test failure.

The law on aftermarket HID and LED lighting in the UK, in detail, with links and references

ECE Regulations 48 and 98 are the ones which apply to HID headlights, and 48 is the one which deals specifically with how HID headlights must be fitted to be legal.

Headlight washers and automatic levelling

Part 6.2.9. "Other requirements" says: "Dipped-beam headlamps with a light source or LED module(s) producing the principal dipped beam and having a total objective luminous flux which exceeds 2,000 lumen shall only be installed in conjunction with the installation of headlamp cleaning device(s) according to Regulation No. 45.”

Part 6.2.6.2.2 says "... devices which are adjusted manually, either continuously or non-continuously, shall be permitted, provided they have a stop position at which the lamps can be returned to the initial inclination defined in paragraph 6.2.6.1.1. by means of the usual adjusting screws or similar means. These manually adjustable devices shall be operable from the driver's seat."

However, part 6.2.9. says “With respect to vertical inclination the provisions of paragraph 6.2.6.2.2. above shall not be applied for dipped-beam headlamps:

(a) With LED module(s) producing the principal dipped beam; or

(b) With a light source producing the principal dipped beam and having an objective luminous flux which exceeds 2,000 lumen."

So, these laws say you must have washers and automatic levelling only if the light source is more than 2,000 lumens total output, or the light is produced by LEDs (of any brightness), according to (b), above.

But, it's worth pointing out that it’s not possible to measure the total light output accurately at the roadside, or in the MOT station - a light meter can only measure intensity of light at one point, and this rule applies to total light output.

Therefore, as long as you have a manually-operated light levelling system - e.g. a little adjuster wheel on the dashboard - this also seems to be acceptable according to the wording above, unless of course somebody goes to the trouble of having your lights' output measured to test whether they put out more than 2,000 lumens.

Information on adjusting headlight aim

Part 6.2.6.1.1. specifies that lights should be aimed with an empty car and a person in the driver’s seat: "The initial downward inclination of the cut-off of the dipped-beam to be set in the unladen vehicle state with one person in the driver's seat...”

A quick note about manual headlight adjusters

Annex 8 is worth bearing in mind: part 1.2. says: "The "0” position [on a manual headlight adjuster] corresponds to the initial inclination according to paragraph 6.2.6.1.1. of this Regulation."

So, to be legal, the highest your headlights can be aimed should be the legal maximum angle; it shouldn’t be possible to aim your headlights too high - there’s some more info below in the MOT test section.

Switching between dip and main beams

Part 6.2.7. "Electrical connections” tells us that if you have an HID dipped beam, it has to stay on when you switch to main beam: "In the case of dipped-beam headlamps according to Regulation No. 98, the gas discharge light sources shall remain switched on during the main-beam operation."

• You can download a PDF-format version of Regulation 48 here.

The MOT test rules from VOSA, in detail, with links and references

What the MOT handbook says about HID and LED headlamps

Part 1.7 of the MOT handbook says washers and self-levelling must work, where fitted:

"Vehicles equipped with High Intensity Discharge (HID) or LED dipped beam headlamps may be fitted with headlamp washers and a suspension or headlamp self levelling system. Where such systems are fitted, they must work; however, it is accepted that it may not be possible to readily determine the functioning of self levelling systems. In such cases, the benefit of the doubt must be given." (My emphasis, not VOSA's)

A vehicle may be rejected if the tester finds "a headlamp levelling or cleaning device inoperative or otherwise obviously defective.” (rejection reason 2).

No mention is made of “missing” systems, so it’s acceptable to have no headlamp washers or automatic beam levelling. That said, if you do have headlight washers or beam levelling, they must work.

You can view this information here on the official MOT info website.

HID headlights must turn on straight away

Rejection reason 4a says, "[the tester may reject the vehicle if] a headlamp does not operate immediately when selected on dipped or on main beam”.

So, if you fit a “bi-xenon” kit which replaces your flash-to-pass main beam, it MUST ignite immediately and brightly, every single time. The best way to ensure this is to source high-quality ballasts and matched lamps; for example, OEM-specification kit.

HID headlights must be mainly yellow or white

Rejection reason 5b: "[the tester may reject the vehicle if] an obligatory headlamp shows light that is not substantially white or yellow”.

In effect, this means that you should not fit lights which are obviously blue (or any colour other than white), which means lights marketed as having a colour temperature higher than around the 5,000K mark, although light colour is quite a subjective test.

It’s worth bearing in mind that you get better light output, and less glare and scattering in fog, with 4,300K “standard” colour lamps than more blue, “colder” light colours. The more blue the light - i.e. the higher the colour temperature - the less-well you can see at night.

The human eye “sees” objects lit with blue light less sharply than those lit with more yellow light. As a test, try looking at the flashing blue lights on a police car from a distance and note how the edges of the light aren’t clearly defined, but the flashing yellow lights of a service vehicle will have better-defined edges. For a better scientific explanation, please see this web page.

Lastly, the lights should match each other’s colour

Rejection reason 6: "An obligatory main or dipped beam headlamp intended to be a matched pair ... do not emit light of the same colour”.

To avoid this problem, you should use a matched pair of HID lamps and ballasts - again, buying better quality gear is recommended as you should receive parts which are manufactured to tighter tolerances. Avoid cobbling a kit together from odds and ends :)

It’s also worth bearing in mind that you should aim to replace bulbs as pairs, unless one has died a premature death, for example through accidental breakage.

You can buy OEM-spec HID lamps which are slightly more blue than 4,300K to match an existing older bulb, but since matched bulbs should have a similar lifespan, when one dies, the other will probably not be far behind it, so replacement in pairs is recommended. New 4,300K bulbs will also have a higher light output than an old 4,300K bulb whose colour has shifted closer to 5,000K.

Beam patterns

Part 1.8 covers how the beams should be aimed:

• “Dip beam headlamps are aimed so they do not dazzle, ie the beam image brightest part is aimed at least 0.5% below the horizontal"
• “Main beam headlamps are aimed so that the beam image centre is on or slightly below the horizontal."
• More info here on the official MOT guide website.

Headlight aim

Part 1.8 also says, "where driver’s beam aim controls are fitted the beam aim should be tested without altering the control setting except where this would result in failure for beam aim being too low. In such cases the beam aim should be re-checked with the control set at its ‘highest’ position.”

So, if you have a manual beam height adjuster, the beam MUST NOT be too high when set to its highest setting.

It also says: "when adjusting European ‘E’ beam headlamps they should be set in accordance with the type approval marking which is either close to the vehicle manufacturer’s plate or the headlamp. For vehicles without a marking, the downward aim should be set to:

1. 1.3%, if the headlamp centre is not more than 850 mm from the ground
2. 2.0%, if the headlamp centre is more than 850 mm from the ground."

More about that Department for Transport document

The Department for Transport published a document in 2010, snappily titled “Aftermarket HID headlamps”, which says the following, but remember - this is not The Law, and therefore does not carry any sway, so if somebody refers you to this document or a variation of it, you can rest assured that the information above from ECE Regulation 48 and VOSA supersedes this.

There is even a paragraph in this article which says that this is the opinion of the DfT and not the law: “NOTE: The information in this document is a summary of DfT’s understanding of what the law requires. However, ultimately the interpretation of the law is a matter for the courts based on individual facts of any particular case. You are therefore advised to consult the relevant legislation and, if necessary, seek independent advice."

What the article says

"In the Department for Transport's (DfT) view it is not legal to sell or use after market HID lighting kits, for converting conventional Halogen headlamps to HID Xenon. If a customer wants to convert his vehicle to Xenon HID he must purchase completely new Xenon HID headlamps. The reason for this is that the existing lens and reflector are designed around a Halogen filament bulb, working to very precise tolerances. If one places a HID "burner" (bulb) in the headlamp, the beam pattern will not be correct, there will be glare in some places and not enough light in other places within the beam pattern.

 

The following is the legal rationale: 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 aftermarket, 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 aftermarket to meet the same safety standards as those for new vehicles. The same level of safety should apply.

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); and
• 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."

• At the risk of repeating a point I made earlier, the article also says: “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.”

  This suggests quite strongly that if you fit a projector designed for HID lamps into a reflector headlight so that the resulting beam pattern is correct, you won’t be in breach of the DfT’s guidelines on aftermarket HIDs. That said, you would have modified an approved car part, so while it might still have a type approval mark such as “E11”, it wouldn’t be valid, although an MOT tester or police officer might have a hard time proving this.

• Examples of retrofit projector kits are available from a number of places, ranging from poor quality to highly-commended, and ranging from cheap to expensive.

  As is always the case, expensive doesn't necessarily mean good, but one company I have found which you may wish to look at are American company The Retrofit Source (theretrofitsource.com), who sell high quality projectors designed for HID lamps, which mount by screwing into the bulb mounting hole in a reflector headlight. You can find examples of these kits here and here. The second kit even allows the use of OEM specification (i.e. E-marked) "D2S" HID lamps.

  And, for the record, I'm just a happy customer of The Retrofit Source, and sadly I don't get paid for my endorsement!

• You can find this document here in PDF format.

Comments and corrections

If you'd like to send me a comment or think I've made a mistake somewhere in this article, please let me know - you can send me an e-mail here.

Want a memorable link to this page? You can bookmark bit.ly/hidkitlegaluk.

Thanks! /Alex - March 2015