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Legal Height for driving lights?


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I am doing the C2C in a couple of weeks and thought of adding a couple of driving/spotlights to come on with main beam. The easiest place to fit these on my TR7 is quite low to the ground and I wondered if :

a) there was a legal minimum height off the road for driving (not Fog) lights

b) whether lights mounted low down would actually be of any benefit?

thanks,

Allan

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Hi,

I don't believe there is any minimum height for driving lights ( fog lights have a maximum allowable height). The regulations are in 'The Road Vehicles Lighting Regulations 1989' which you can find online, spot lights are classed as optional main beam lights, and are covered under the main beam headlamp section.

How much use low mounted lights are is debatable, you tend to get a lot of shadow behind undulations in the road. Trial and error really.

Mike.

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I have not looked into this but I would suggest that any light that "comes on with the main beam" would be subject to the minimum height and also to pattern of those main lights.  This of course is to prevent dazzling oncoming road users in that second or two before they are switched to dip.  I sure you'll find that additional lights would be required, by law, to be separately switched ..as indeed are both spot & fog lamps.

Headlamps are of course set to a minimum height so they might shine down onto the road surface, and their spread includes the curbside ..more so than the crown of the road.  Positioned very low I'm sure you'll find that you'll be illuminating the trees and hedgerow more than the road surface.  If otherwise tilted down ..then their reach in front of the car would be too short to be useful at normal road speeds.   TR7 rally cars generally fit them at or above the bumper and sometimes even at roof level. 

Fog lamps are positioned low in the hope that their light cuts through the fog below the driver's eye level rather than being dissipated by the water droplets at his / her eye level.  One assumes in fog that road speeds will be lower and therefore the distance they illuminate along the road need not be so far. 

Pete.

 

Edited by Bfg
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In old fashioned money from memory driving lights must be between 24" & 36" from the ground

& automatically extinguish when headlamps are dipped. Remember the Hillman Imp, the headlamps

were too low so Routes adopted the quick fix of longer front springs, until modifying the suspension

 mountings.

     

                                          Harvey 

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41 minutes ago, HSM said:

...lights must be between 24" & 36" from the ground...

But is that measurement to the top edge, the centre, or the bottom edge of the light glass?

It’s a problem I had when I worked with kit-cars. I telephoned and wrote to several people in the Department of Transport to try to find the answer and it seemed that everyone I dealt with had a different “Opinion”.

Advice like “What I think you should do is…” would be given.

I think the only person who really knew the answer was the person who wrote the regulations.

Nobody seemed to know who that was.

 

Charlie.

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I can't find any height requirements in the lighting regulations or MOT test inspection requirements for 'optional main beam' lights (there are no references to 'spot' or 'driving' lights). 

They are required to be wired so as to switch off when headlights are dipped.

Mike.

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The measurement is to the centre of the lens. Regarding MOT requirements no measuring 

is required. 

                                      Harvey

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Back to basics.

what are your current headlamps?   Is it reasonable to improve their light output by substitution of brighter bulbs or different lamp units with better light spread.

would improved headlamps remove the need for extra lamps?

Changing the old bulb type BPF headlamps on my TR to Wipac Quadoptic headlamps was one of the first mods I did back in 1973.  Lots of people at the time fitted Cibie super oscars etc as they were the lamp of choice in the rally world.    The halogen bulbs are rated at the same power consumption as the original incandescent filaments but give brighter light.  If the extra lamps are fitted you are adding a drain to the alternator charging circuit.   The lens is a better design giving a projected cut off flat topped beam instead of the globule of light the BPF unit gave.

Peter W

Edited by BlueTR3A-5EKT
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2 hours ago, HSM said:

...The measurement is to the centre of the lens...

Ahhh...

That may well be correct.

But where is it written in a government publication?

(I'm not being argumentative, by the way, just curious as to where you got the information from. I looked at the lighting regs and can find no mention of it.)

 

Charlie.

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Hi Charlie

                        I found this on page 7 of the Road Vehicle Lighting Regulations.Expression Minimum

height above ground. Meaning The height below which no part of the illuminated area in the case

of a lamp, or the reflecting area in the case of a retro reflector, extends when the vehicle is at

its kerbside weight and when each tyre with which the vehicle is fitted is inflated to the pressure

recommended by the manufacturer of the vehicle. I leave you all to make some sense of that.

                              

                                                           Best of luck

                                                                                     Harvey

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Harvey,

Brilliant !!!

Thank you for that. (I was hoping that you weren’t going to say that you heard it from a bloke named Eric, you know from the pub.)

 

What it says seems to suggest that the minimum distance from the ground is measured from the lowest part of the light circumference.

I guess that means that the maximum distance from the ground is measured from the highest part of the lamp circumference.

I also guess that the maximum distance from the edge of the car (Which I think is 400 mm) is measured to the outer most edge of the light circumference.

Measuring it that way can take into account the light output from any diameter of lamp.

 

All that seems to make sense.

(I think…)

 

Charlie.

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Thanks for all of this. I have today fitted LED bulbs in the headlights & took it to my friendly MOT tester to check the alignment was ok, so asked him the question. As Mike says additional lights are not mentioned in the MOT and as far as he is aware there is no regulation regarding their height from the road. As long as I wire them to only be on with the headlights he does not see an issue.

Interestingly I have just measured the centre of the existing headlights at around 27" from the ground so perhaps Harvey's regulation applies just to the main headlights?

Thanks all,

Allan

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8 hours ago, stillp said:

There is a specification of the minimum height for headlamps in Schedule 4. Part 1 of the Road Vehicles Lighting Regulations 1989: https://www.legislation.gov.uk/uksi/1989/1796/schedule/4

Pete

This height requirement is for dipped beam headlights. I still can’t see any height requirement for main beam headlights, spot or driving lights being optional main beam lights (schedule 5 of the quoted legislation). Like Charlie, I’m not trying to be argumentative, but nobody has yet shown where any height requirement for these lights is written down.

Mike.

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I agree. There's a maximum height for main beam headlights, 1200 mm, but no minimum, and the same for fog lamps, but I can't see anything for spot lamps. "Driving lamps" are neither defined nor considered.

Pete

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A previous Honda Accord that I had in the 1990s has fog lights set into the front bumper and were definitely below 1200mm they were probably around 400mm. 1200mm is a high limit. It is close to four feet above the ground.

TT

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18 hours ago, stillp said:

Yes Tony, 1200 mm is the maximum.

Pete

so we can probably stick them the roof of our Tr's

like Iain's  lovely works rally car has the single (admittedly Spot light)

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On 6/24/2021 at 4:04 PM, Allan Westbury said:

Thanks for all of this. I have today fitted LED bulbs in the headlights & took it to my friendly MOT tester to check the alignment was ok, so asked him the question. As Mike says additional lights are not mentioned in the MOT and as far as he is aware there is no regulation regarding their height from the road. As long as I wire them to only be on with the headlights he does not see an issue.

Interestingly I have just measured the centre of the existing headlights at around 27" from the ground so perhaps Harvey's regulation applies just to the main headlights?

Thanks all,

Allan

Think you will find only on main beam, not dip.

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