"Rod Speed" wrote in message
...
It's a legal requirement in some countries that there is only one rear
fog. Presumably to avoid confusion with brake lights.

I wondered if that was the case, given that a lot of recent cars have
only one fog light. My previous cars had two white lights in the clusters
for reversing and two red lights for fog, but there was no bulb in the
nearside fog light - so I added one, on the grounds that (IMHO) *all*
front and rear lights should be in pairs, to define the car's width.

Trouble is that its then easy to confuse with a car
heading towards you in your lane in heavy fog.

If it was heading towards you (assuming it wasn't reversing!) you would see
its two *white* lights - either sidelights, headlights or front fog lights -
at the front.

I was talking about having two *red* lights at the back - in pairs, as for
all other lights such as tail lights and brake lights (OK, there's usually a
third central high-level brake light).

No-one complains about having two tail lights, and fog lights are (to my
mind) just extra-bright tail lights which allow your car to be seen (and an
estimate made of its distance away, from the separation of the lights) from
further away than tail lights allow through fog. They do the same job as
tail lights - "I'm here and this is how wide I am, so you can judge how
close you are to me". They just need to be brighter than tail lights -
firstly because the fog scatters light and secondly because you want to
maintain a greater distance from the car in front than you would in clear
conditions.