John Williamson wrote
dennis@home wrote
John Williamson wrote

The Highway Code is not law, and it admits this in the introduction,
however, it contains references to laws which *must* be obeyed.

It is someone's interpretation of the law.

As it's a Government publication, I'd say it's the Government's
interpretation, which has a pretty good chance of being the correct one.

Not necessarily with the detail being discussed, whether its
legal to have just the fog lights on without the headlights,
particularly when the construction and use is a legal document
and does make it very clear that that is perfectly legal.

However, the only problem from your point of view is that
it's not an interpretation of the law, but a condensed reference
to the laws all road users are required to follow.

That's not a problem from his point of view when the construction
and use is the law and is quite clear on that question of foglight use.

When it say that dipped headlights *must* be used in conditions
of reduced visibility, this is a law which must be complied with.
When it says foglights *may* be used, then they are optional, so,
in conditions of reduced visibility, it is against the law to use
foglights without also having dipped headlamps lit as well.

Which law states this?
The construction and use doesn't.

Road Vehicle Lighting Regulations 1989, sections 25 and 26.
As quoted in Rule 226 of the HIghway code.

Pity about the construction and use regs he quoted.

It is, however, perfectly legal to use dipped headlamps without
folglamps, even when visibility is everely reduced. This is whay the
vast majority of vehicles that I drive have the foglights wired in
such a way that if the dipped headlamps are off, then the foglights
will not work. The foglights also turn off when the main beam
headlamps are on.

Which cars?

Currently, IIRC, Ford Focus, Ford Fiesta, Ford Galaxy, Various Scania
and Volvo coaches, and at least one Mercedes minubus. The Ford Torneo
minibus may have the same interlock, but I've not driven it for a while.
The VW Sharan had the same system, but that was scrapped a while ago, as
was the Mondeo.