PeterC :
On Sat, 14 Apr 2012 21:46:08 +0100 (BST), Dave Liquorice wrote:

But I'm talking about proper fog where you're reduced to walking pace.

Proper fog that most people never ever see.

I think I've had to drop to front fogs just a handful of times up
here on the North Pennines where we almost live in the hill fog. When
the snow poles are too far apart to see from one to the next, there
is thick fog visibilty about 15' max and everything is also smoothly
covered in snow with no tracks to follow it makes for an
"interesting" drive. Fast walking pace, concentration, and "if it
gets bumpy I'm probably no longer on the road". B-)

Last had that coming home from walking on Kinder Scout. Brilliant day on the
tops but cloud below 1500'.
On the last roundabout on the southern edge of Derby I lost the kerb and had
to go round again; I could just see the signs fron about 5 yards away.

You can see why it makes sense to fit proper front fog lights to cars
even though they're only needed once in a blue moon. When you need them,
you really need them. It's a pity about those prats that switch them on
at the first hint of mist, and take their time turning them off again.

--
Mike Barnes

On Sun, 15 Apr 2012 00:00:01 +0100, wrote:

Rear foglights should only be used when visbility is below 100 metres,

Correct.

so speed needs to be restricted too. Most peeps switch on rear fog
lights as soon as there's a hint of mist,

Only stupid prats but there does seem to be a lot of them about. If
it's having them on when visibilty is 100m it's leaving them on in
traffic.

The regulations state that only one rear fog light is allowed,

Rubbish many cars have two rear fog lights. It's only the smaller
cheaper cars that have one and the coresponding place in the other
light cluster has the reversing light.

and that must be on the offside,

True if there is only one.

--
Cheers
Dave.

On 15 Apr 2012 09:07:56 GMT, Huge wrote:

My Disco 3 has a mechanical interlock in the switch which means you
cannot switch the fogs on without having the headlamps on, and the front
fogs come on before the rear ones. Both of which I find bizarre and
irritating.

Also means that the rear fogs get turned off automatically when you
turn off the main lights. Years ago I suspect the main reason for
rear fogs being on when they shouldn't have been was due to lack of
interlock/self cancelling and tiny tell tale out of the drivers
normal view.

Surprised a DIII has a mechanical interlock, both DII's I've had they
have been under control of the BCU. Are the front "fogs" real fogs or
"auxillary driving lights"? A real fog has low wide beam with the cut
off on the ground at around 30' or less from the front of the
vehicle. No good for night driving on their own.

--
Cheers
Dave.

Dave Plowman (News) wrote:
In article ,
wrote:
On 14 Apr,
"Dave Plowman (News)" wrote:

Always. That's why foglights are low mounted and illegal in good
visibility.

Can you quote evidence of that? I'm sure that was the case in the
60s and have trawled the net to find the rules for how high lights
must be to be used in good visibility and failed miserably in
finding any evidence of the illegality of the current spate of
foglights in good visibility.

You can't have tried very hard. It's in the highway code.

http://www.direct.gov.uk/en/TravelAn...code/DG_069859

although that seems to suggest they must be used with headlights.
Which completely defeats the purpose of them.

If the headlights were good in fog - why have specialised lighting
just for it?

Exactly! It's fairly rare for any fog lights to be needed. Rear
foglights should only be used when visbility is below 100 metres, so
speed needs to be restricted too. Most peeps switch on rear fog
lights as soon as there's a hint of mist, and don't slow down,
being unaware that the fog lights mask their brake lights and
signals, being much brighter.

They are normally the same brightness as stop lamps or indictors.
They are also very useful in heavy rain in daylight. They allow you
to see there is a car in front before you can actually see the car
itself.

The regulations state that only one rear fog light is allowed, and
that must be on the offside, to reduce the likelyhood of them being
mistaken for brake lights.

Both my cars have twin rear fog lights.

When I had a Berlingo (only one rear fog light on the OS) I got a MOT
failure for a NS rear fog light not working and a £5 bill to fit a new bulb.
Bet you can guess what I did with that bill:-)

The mutual agreement reached between myself and the owner of the garage
after the argument was that it would be best if I did not use their garage
again.

--
Adam

In article ,
Rod Speed wrote:
http://www.direct.gov.uk/en/TravelAn...code/DG_069859

although that seems to suggest they must be used with headlights.

No it does not.

I wouldn't expect you to understand English. Thanks for confirming it.
It must have been the likes of you who wrote that HC rule.

--
*Middle age is when it takes longer to rest than to get tired.

Dave Plowman London SW
To e-mail, change noise into sound.

On Sun, 15 Apr 2012 00:00:01 +0100
wrote:

The regulations state that only one rear fog light is allowed,and
that must be on the offside, to reduce the likelyhood of them being
mistaken for brake lights.

http://www.legislation.gov.uk/uksi/1...hedule/11/made states
that it's mandatory to have (at least) one rear fog lamp but 2 lamps are
optional. In the event of only one lamp then it must be on the
centre-line or offside of the vehicle but there are no restrictions if
2 lamps are fitted.

--
Mike Clarke

Mike Clarke wrote:

wrote:

The regulations state that only one rear fog light is allowed,and
that must be on the offside

http://www.legislation.gov.uk/uksi/1...hedule/11/made

states that it's mandatory to have (at least) one rear fog lamp but 2
lamps are optional. In the event of only one lamp then it must be on
the centre-line or offside of the vehicle but there are no
restrictions if 2 lamps are fitted.

So you could be stupid and have two on the nearside, so close together
that they're barely distinguishable, it only mentions separation between
stop and fog lamps ...

"Dave Plowman (News)" wrote in message
...
In article ,
dennis@home wrote:
I realise you're not technical, Dennis, but multiple lamp halogens
could do exactly the same thing. Although just why you'd want to
escapes me.

I realise you don't know as much as you think but the optics to do that
with halogen lamps would be rather difficult. The filament would have
to be too long to actually make the sharp cut off required.

A sharp cutoff is achieved with a french flag. Many many cars with halogen
and HID units do this. LEDs will be no different. It's down to the optics,
not light source.


What makes you think LEDs need a baffle to throw half the light away?


But I guess you don't know much about the differences between LED lamps
and filament lamps.

Obviously a lot more than you.

Obviously not.


But it's nice to see you're impressed by computer animation.

Its not all animation, but I realise that you can't tell the difference.
Even Mickey mouse cartoons are more impressive than you these days.

If they have to resort to animation, it means real world conditions don't
show the effects they're conning the likes of you into believing. Are you
actually dribble? He's another who believes everything he sees in adverts.

I wonder how many things started out by someone showing a drawing, or a
slide show to someone else before it became something real..
lets think a few seconds..
that would be almost everything in the last decade or three.

In article ,
dennis@home wrote:
A sharp cutoff is achieved with a french flag. Many many cars with
halogen and HID units do this. LEDs will be no different. It's down to
the optics, not light source.


What makes you think LEDs need a baffle to throw half the light away?

What makes you think there's another way of doing it? Not a knowledge of
optics, obviously.

--
*Marriage changes passion - suddenly you're in bed with a relative*

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
dennis@home wrote:
A sharp cutoff is achieved with a french flag. Many many cars with
halogen and HID units do this. LEDs will be no different. It's down to
the optics, not light source.


What makes you think LEDs need a baffle to throw half the light away?

What makes you think there's another way of doing it? Not a knowledge of
optics, obviously.

So do you know the difference between a filament and a silicon junction?

On Apr 14, 9:58*pm, "dennis@home"
wrote:
"Dave Plowman (News)" wrote in ...

In article ,
* John Williamson wrote:
LEDS in fixed installations are noticeably more efficient than filament
bulbs, as they use a switched mode supply, with a total comsumption of
about 10% or 15% that of the filament bulbs for the same light output.

Cars use SMPS too for LEDs.

A difference is that 12v tungsten are already more efficient than mains
ones.

I'd love to see *any* LED with the same light output as halogen mains. And
by that I mean a near 360 degree output of the same colour spectrum. Not
just measured by pointing some crude light meter at it. And using the very
worst possible tungsten as the comparison.

Let us know when you can get halogen lights that can do thishttp://www.youtube.com/watch?v=znivDtjl1N4

Citreon DS famously had steering headlights, think there has been a
few since, self levelling are very common via tilt servo.

Advantage here is probabkly very efficient optics getting most of
light from LED in collimated beam and then using multiple beams to
cover the area.

Works well in a car becasue area needing lit is relatively narrow.

Cheers
Adam

Dave Plowman (News) wrote
Rod Speed wrote
Dave Plowman (News) wrote

http://www.direct.gov.uk/en/TravelAn...code/DG_069859

although that seems to suggest they must be used with headlights.

No it does not.

I wouldn't expect you to understand English. Thanks for confirming it.
It must have been the likes of you who wrote that HC rule.

You never could bull**** your way out of a wet paper bag.

On 15/04/2012 18:59, Dave Plowman (News) wrote:
In ,
wrote:
A sharp cutoff is achieved with a french flag. Many many cars with
halogen and HID units do this. LEDs will be no different. It's down to
the optics, not light source.


What makes you think LEDs need a baffle to throw half the light away?

What makes you think there's another way of doing it? Not a knowledge of
optics, obviously.


Seriously?

you do realise that you just modulate the drive current to turn a LED
on/off.

No mechanical parts required.

cheers

David

In article ,
Huge writes:
On 2012-04-15, David wrote:
On 15/04/2012 18:59, Dave Plowman (News) wrote:
In ,
wrote:
A sharp cutoff is achieved with a french flag. Many many cars with
halogen and HID units do this. LEDs will be no different. It's down to
the optics, not light source.


What makes you think LEDs need a baffle to throw half the light away?

What makes you think there's another way of doing it? Not a knowledge of
optics, obviously.


Seriously?

you do realise that you just modulate the drive current to turn a LED
on/off.

No mechanical parts required.

And that directs the light in a particular direction how, exactly?

An LED-based headlamp is likely to be multi-LED source.
With LEDs being tiny sources anyway, it's relatively easy to
build optics around them to very accurately direct each LED
source to a specific part of the output beam. This means you
can do beam dipping simply by switching off those LEDs which
give the high beam. As I eluded in another post, you could
have beams which are much more dynamically adjustable than
just main/dip. Could also vary intensity of parts of the beam,
and unlike either filament or HID, colour shift would be
minimal if you did this.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 15/04/2012 22:07, Huge wrote:
On 2012-04-15, wrote:
On 15/04/2012 18:59, Dave Plowman (News) wrote:
In ,
wrote:
A sharp cutoff is achieved with a french flag. Many many cars with
halogen and HID units do this. LEDs will be no different. It's down to
the optics, not light source.


What makes you think LEDs need a baffle to throw half the light away?

What makes you think there's another way of doing it? Not a knowledge of
optics, obviously.


Seriously?

you do realise that you just modulate the drive current to turn a LED
on/off.

No mechanical parts required.

And that directs the light in a particular direction how, exactly?



by having multiple LEDs that you simple switch on/off

this is not a smooth transition but rather a discrete group of settings
- a digital rather than analogue directional control if you like.

In article ,
dennis@home wrote:
What makes you think there's another way of doing it? Not a knowledge
of optics, obviously.

So do you know the difference between a filament and a silicon junction?

LEDs don't need optics, then?

--
*The average person falls asleep in seven minutes *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
David wrote:
On 15/04/2012 18:59, Dave Plowman (News) wrote:
In ,
wrote:
A sharp cutoff is achieved with a french flag. Many many cars with
halogen and HID units do this. LEDs will be no different. It's down
to the optics, not light source.


What makes you think LEDs need a baffle to throw half the light away?

What makes you think there's another way of doing it? Not a knowledge
of optics, obviously.


Seriously?

you do realise that you just modulate the drive current to turn a LED
on/off.

No mechanical parts required.

Which discussion do you think you're reading?

--
*Can atheists get insurance for acts of God? *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Andrew Gabriel wrote:
An LED-based headlamp is likely to be multi-LED source.
With LEDs being tiny sources anyway, it's relatively easy to
build optics around them to very accurately direct each LED
source to a specific part of the output beam.

High power LEDs are tiny sources? Some data, please.

However, to provide a sharp cutoff, you'll still need some form of flag.
Just like any other light source.

--
*When it rains, why don't sheep shrink? *

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
dennis@home wrote:
What makes you think there's another way of doing it? Not a knowledge
of optics, obviously.

So do you know the difference between a filament and a silicon junction?

LEDs don't need optics, then?

Stop wriggling.

In article ,
dennis@home wrote:


"Dave Plowman (News)" wrote in message
...
In article ,
dennis@home wrote:
What makes you think there's another way of doing it? Not a
knowledge of optics, obviously.

So do you know the difference between a filament and a silicon
junction?

LEDs don't need optics, then?

Stop wriggling.

Ok Dennis. Explain how you get a sharp cutoff on an LED without using
optics. My breath is bated.

Hint: Just how the light is produced - filament or discharge etc make
little difference. The more of a point source it is just makes the optics
easier.

--
*There are two sides to every divorce: Yours and **** head's*

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote:
In article ,
dennis@home wrote:


"Dave Plowman (News)" wrote in message
...
In article ,
dennis@home wrote:
What makes you think there's another way of doing it? Not a
knowledge of optics, obviously.

So do you know the difference between a filament and a silicon
junction?

LEDs don't need optics, then?

Stop wriggling.

Ok Dennis. Explain how you get a sharp cutoff on an LED without using
optics. My breath is bated.

Hint: Just how the light is produced - filament or discharge etc make
little difference. The more of a point source it is just makes the optics
easier.


Dennis seems to be hitting new depths. Power LEDs generally have one or two
reflectors (sometimes the manufacturer has a reflector in the LED ) and
usually two lenses, one incorporated in the package and a second lens and
reflector for the array. Blathering away than a lens is not required is,
errm total ********, again.

In article
,
Steve Firth wrote:
Dennis seems to be hitting new depths. Power LEDs generally have one or two
reflectors (sometimes the manufacturer has a reflector in the LED ) and
usually two lenses, one incorporated in the package and a second lens and
reflector for the array. Blathering away than a lens is not required is,
errm total ********, again.

Indeed - I've never even looked at a car headlight LED, but laws of
physics don't change regardless of what Dennis wants.

But having at least some of the optics as part of the 'bulb' is nothing
new - some tungsten Lucas ones had a built in flag in the '50s.

--
*If love is blind, why is lingerie so popular? *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
"Dave Plowman (News)" writes:
In article ,
Andrew Gabriel wrote:
*An LED-based headlamp is likely to be multi-LED source.*
With LEDs being tiny sources anyway, it's relatively easy to
build optics around them to very accurately direct each LED
source to a specific part of the output beam.

High power LEDs are tiny sources? Some data, please.

Um, read what I wrote above again...

However, to provide a sharp cutoff, you'll still need some form of flag.
Just like any other light source.

The difference from other light sources is the size - they're
tiny - much smaller than a filament, or the arc in a HID.
What this enables you to do is to build optics which
concentrate the light in very specific directions. The ideal
light source for this is a point which you can use to generate
images with sharp boundaries. As that light source grows in
size, you can think of it as an out-of-focus point, and it
will generate correspondingly out-of-focus boundaries. An
LED is nearer to a point source than existing technologies.

'Flag' is too loosely defined in this case. You may have a
set of LED with optics which give you the dip beam pattern,
and another set which give you the (main beam) - (dip beam)
pattern. No 'flag' is required to block anything, it's
simply that the optics only direct the light where it's
wanted.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
Andrew Gabriel wrote:
'Flag' is too loosely defined in this case. You may have a
set of LED with optics which give you the dip beam pattern,
and another set which give you the (main beam) - (dip beam)
pattern. No 'flag' is required to block anything, it's
simply that the optics only direct the light where it's
wanted.

To provide a very sharp cutoff, you'd need rather a large number of LEDs.
;-)

The size of the source (within reason) only make a difference to the size
and complexity of the optics. If this weren't the case cinema projectors
etc could never have been made to work well.

--
*War does not determine who is right - only who is left.

Dave Plowman London SW
To e-mail, change noise into sound.

On Apr 14, 10:45*pm, "dennis@home"
wrote:
"charles" wrote in message

...









In article ,
* Mike Clarke wrote:
On Sat, 14 Apr 2012 13:18:50 +0100
John Williamson wrote:

In town, using dipped beams, the load is more like 150W,
anyway. You'll only use 400W in a situation where you are driving in
foggy conditions or using four high power halogen main beam lights.

How can foggy conditions result in so much more load? A pair of front
foglamps will be the same power as a pair of dipped headlamps and the
rear foglamps will only add 21w each which will only push it up to
about 200w total

'cos most cars, idiotically, only allow you to use the fog lights when the
headlamps are switched on.

Do you mean the rear fogs, I know of none that have front fogs where you
have to have the headlamps on as well.

Shows how much you know.

I have never owned car where you could have the front fogs on without
the headlights.

Try any Ford with the rotary/pull position/headlight/fogs switch for
example. Turn it to off and it pops back in turning the fog lights off
as well.

MBQ

"Man at B&Q" wrote in message
...
On Apr 14, 10:45 pm, "dennis@home"
wrote:
"charles" wrote in message

...









In article ,
Mike Clarke wrote:
On Sat, 14 Apr 2012 13:18:50 +0100
John Williamson wrote:

In town, using dipped beams, the load is more like 150W,
anyway. You'll only use 400W in a situation where you are driving in
foggy conditions or using four high power halogen main beam lights.

How can foggy conditions result in so much more load? A pair of front
foglamps will be the same power as a pair of dipped headlamps and the
rear foglamps will only add 21w each which will only push it up to
about 200w total

'cos most cars, idiotically, only allow you to use the fog lights when
the
headlamps are switched on.

Do you mean the rear fogs, I know of none that have front fogs where you
have to have the headlamps on as well.

Shows how much you know.

I have never owned car where you could have the front fogs on without
the headlights.

2006 corsa works without the headlights on..

In article ,
dennis@home wrote:
Ok Dennis. Explain how you get a sharp cutoff on an LED without using
optics. My breath is bated.

Hint: Just how the light is produced - filament or discharge etc make
little difference. The more of a point source it is just makes the
optics easier.

Well there you are, that is exactly what I said in the first place and
what you have been arguing about since.

Have you ever thought about treatment for your delusions?

I knew you would hang yourself if I let you.

Strangely, I'm still breathing.

--
*If you don't like the news, go out and make some.

Dave Plowman London SW
To e-mail, change noise into sound.

On Apr 16, 10:18*pm, "dennis@home"
wrote:
"Man at B&Q" wrote in ...









On Apr 14, 10:45 pm, "dennis@home"
wrote:
"charles" wrote in message

.. .

In article ,
* Mike Clarke wrote:
On Sat, 14 Apr 2012 13:18:50 +0100
John Williamson wrote:

In town, using dipped beams, the load is more like 150W,
anyway. You'll only use 400W in a situation where you are driving in
foggy conditions or using four high power halogen main beam lights.

How can foggy conditions result in so much more load? A pair of front
foglamps will be the same power as a pair of dipped headlamps and the
rear foglamps will only add 21w each which will only push it up to
about 200w total

'cos most cars, idiotically, only allow you to use the fog lights when
the
headlamps are switched on.

Do you mean the rear fogs, I know of none that have front fogs where you
have to have the headlamps on as well.

Shows how much you know.

I have never owned car where you could have the front fogs on without
the headlights.

2006 corsa works without the headlights on..

So you based your statement on your experience of one car.

MBQ

"Man at B&Q" wrote in message
...


So you based your statement on your experience of one car.

No I based it on fact!
I knew of none where what you said was true, now someone has stated it to be
true on one.

And you based yours on experience of how many?
And how do you get to *most* based on your experience?

At least I didn't make stupid claims.

In article
,
Man at B&Q wrote:
2006 corsa works without the headlights on..

So you based your statement on your experience of one car.

It does seem to vary by make - and possibly by age too. Both my cars allow
the front fogs to be used independently of the headlights. Anything else
would be a nonsense.

However, the HC rule as quoted earlier is ambiguous on this point.
Obviously written by an idiot.

Logically, there is no point in fitting dedicated fog lights if they only
work with headlights, as those headlights will produce light scatter
negating the benefits of a low mounted light with flat top beam designed
to cut under the fog and illuminate the road just in front of the car.

--
*Happiness is seeing your mother-in-law on a milk carton

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote
Man at B&Q wrote

2006 corsa works without the headlights on..

So you based your statement on your experience of one car.

It does seem to vary by make - and possibly by age too. Both my cars allow
the front fogs to be used independently of the headlights. Anything else
would be a nonsense.

However, the HC rule as quoted earlier is ambiguous on this point.

Like hell it is.

Obviously written by an idiot.

Obviously read by an idiot, you.

Logically, there is no point in fitting dedicated fog lights if they only
work with headlights, as those headlights will produce light scatter
negating the benefits of a low mounted light with flat top beam designed
to cut under the fog and illuminate the road just in front of the car.

Which is why the HC rule doesn’t say that they have to be used with the
headlights.

In article ,
Rod Speed wrote:

However, the HC rule as quoted earlier is ambiguous on this point.

Like hell it is.

Thanks for confirming your lack of comprehension. But then since English
isn't your first language it's only to be expected.

--
*Never miss a good chance to shut up.*

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article
,
Man at B&Q wrote:
2006 corsa works without the headlights on..

So you based your statement on your experience of one car.

It does seem to vary by make - and possibly by age too. Both my cars allow
the front fogs to be used independently of the headlights. Anything else
would be a nonsense.

However, the HC rule as quoted earlier is ambiguous on this point.
Obviously written by an idiot.

Logically, there is no point in fitting dedicated fog lights if they only
work with headlights, as those headlights will produce light scatter
negating the benefits of a low mounted light with flat top beam designed
to cut under the fog and illuminate the road just in front of the car.

Its even more confusing when you see cars that have supplemental driving
lamps that aren't fog lamps at all.
These have to work with the headlights.

I should point out that the extra visibility from fog lamps is likely to be
an illusion.
there is no reason why a wide angle beam should penetrate further into the
fog than the headlights and the glare doesn't actually make it so you can't
see further, it just makes it easier on the eyes.

What you need is augmented reality with an IR illuminator and a head up
display fed from an IR camera.
Not that i have seen any really thick fog for the last decade (stuff that
would require you drive below 30).

Dave Plowman (News) wrote
Rod Speed wrote

However, the HC rule as quoted earlier is ambiguous on this point.

Like hell it is.

Thanks for confirming your lack of comprehension.

You never could bull**** your way out of a wet paper bag.

dennis@home wrote
Dave Plowman (News) wrote
Man at B&Q wrote

2006 corsa works without the headlights on..

So you based your statement on your experience of one car.

It does seem to vary by make - and possibly by age too. Both my cars
allow
the front fogs to be used independently of the headlights. Anything else
would be a nonsense.

However, the HC rule as quoted earlier is ambiguous on this point.
Obviously written by an idiot.

Logically, there is no point in fitting dedicated fog lights if they only
work with headlights, as those headlights will produce light scatter
negating the benefits of a low mounted light with flat top beam designed
to cut under the fog and illuminate the road just in front of the car.

Its even more confusing when you see cars that have supplemental driving
lamps that aren't fog lamps at all.
These have to work with the headlights.

I should point out that the extra visibility from fog lamps is likely to
be an illusion.

Fraid not.

there is no reason why a wide angle beam should penetrate further into the
fog than the headlights

They arent just wide angle beams, they are mounted lower than
the headlights for a reason and have a much lower beam cutoff too.

and the glare doesn't actually make it so you can't see further, it just
makes it easier on the eyes.

Even sillier.

What you need is augmented reality with an IR illuminator and a head up
display fed from an IR camera.

Completely off with the ****ing fairys, as always.

Not that i have seen any really thick fog for the last decade (stuff that
would require you drive below 30).

"Dave Plowman (News)" wrote in message
...

However, the HC rule as quoted earlier is ambiguous on this point.
Obviously written by an idiot.

Logically, there is no point in fitting dedicated fog lights if they only
work with headlights, as those headlights will produce light scatter
negating the benefits of a low mounted light with flat top beam designed
to cut under the fog and illuminate the road just in front of the car.

Requirements about the use of headlamps and front fog lamps

25.-(1) Save as provided in paragraph (2), no person shall use, or cause or
permit to be used, on a road a vehicle which is fitted with obligatory
dipped-beam headlamps unless every such lamp is kept lit-

(a)during the hours of darkness, except on a road which is a restricted
road for the purposes of section 81 of the Road Traffic Regulation Act 1984
by virtue of a system of street lighting when it is lit; and .

(b)in seriously reduced visibility. .

(2) The provisions of paragraph (1) do not apply-

(a)in the case of a motor vehicle fitted with one obligatory dipped-beam
headlamp or a solo motor bicycle or motor bicycle combination fitted with a
pair of obligatory dipped-beam headlamps, if a main-beam headlamp or a front
fog lamp is kept lit; .

(b)in the case of a motor vehicle, other than a solo motor bicycle or motor
bicycle combination, fitted with a pair of obligatory dipped-beam headlamps,
if- .
(i)a pair of main-beam headlamps is kept lit; or .
(ii)in seriously reduced visibility, a pair of front fog lamps which is so
fitted that the outermost part of the illuminated area of each lamp in the
pair is not more than 400 mm from the outer edge of the vehicle is kept lit;


Clear now?

I wonder where the bit about only using them in falling snow or fog is?

In article , dennis@home
wrote:

[Snip]

I should point out that the extra visibility from fog lamps is likely to
be an illusion. there is no reason why a wide angle beam should
penetrate further into the fog than the headlights and the glare doesn't
actually make it so you can't see further, it just makes it easier on
the eyes.


It's not so much the wide beam angle, but the very narrow horizontal one
which helps. In the '60s, when these things were self fit extra, I did a
lot of trial & error tests. We also got quite a bit of fog in those days.

What you need is augmented reality with an IR illuminator and a head up
display fed from an IR camera. Not that i have seen any really thick fog
for the last decade (stuff that would require you drive below 30).

You've been lucky. I've ceratinly had to crawl (at 20mph) quite recently

--
From KT24

Using a RISC OS computer running v5.18

In article ,
dennis@home wrote:
Logically, there is no point in fitting dedicated fog lights if they
only work with headlights, as those headlights will produce light
scatter negating the benefits of a low mounted light with flat top
beam designed to cut under the fog and illuminate the road just in
front of the car.

Its even more confusing when you see cars that have supplemental driving
lamps that aren't fog lamps at all.
These have to work with the headlights.

It only confuses if you don't know your car.

I should point out that the extra visibility from fog lamps is likely to
be an illusion. there is no reason why a wide angle beam should
penetrate further into the fog than the headlights and the glare
doesn't actually make it so you can't see further, it just makes it
easier on the eyes.

It's the low mounting of the lamp that makes the difference. The actual
beam, less so.

--
*Parenthetical remarks (however relevant) are (usually) unnecessary *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
dennis@home wrote:
Requirements about the use of headlamps and front fog lamps

[snip]

What is that quoted from? It looks more like construction and use regs.
The highway code is the more important one.

--
*Why do they put Braille on the drive-through bank machines?

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Rod Speed wrote:
Dave Plowman (News) wrote
Rod Speed wrote

However, the HC rule as quoted earlier is ambiguous on this point.

Like hell it is.

Thanks for confirming your lack of comprehension.

You never could bull**** your way out of a wet paper bag.

Here's the rule again since you probably couldn't find it unless someone
does it for you.

************

226

You MUST use headlights when visibility is seriously reduced, generally
when you cannot see for more than 100 metres (328 feet). You may also use
^^^^
front or rear fog lights but you MUST switch them off when visibility
improves (see Rule 236).

**********

Since, as I said, you have little comprehension of the English language
I've included the definition of 'also' below:-



Collins GEM English Dictionary

also adv. in addition; too.


Is that clear enough even for the likes of you? 'Too', after all, is a
pretty simple word.

--
*Parenthetical remarks (however relevant) are (usually) unnecessary *

Dave Plowman London SW
To e-mail, change noise into sound.