"Andrew Gabriel" wrote in message
.. .
In article ,
"nightjar" nightjar@insert my surname here.uk.com writes:

You can buy 18W SOX luminaries from your local electrical wholesaler that
will be more than adequate for lighting the average domestic drive. They
look not dissimilar to square bulkhead lights, but mounted horizontally,
with the glass facing down. Personally, I prefer 2 x 9W or 4 x 9W low
energy
floodlamps, which have shorter start-up times.

SOX (low pressure sodium) have a particularly long run-up time,
typically 9 minutes for the larger sizes (never played with the
low power ones, but might be a bit faster because they aren't
as efficient).

Probably about the same. I have them outside my factories.

SON (high pressure sodium) are significantly
faster at around 2 minutes (just measured a 250W one -- 70W is
probably not much different).

I've never measured them, but you are probably right. I use them as high bay
lights inside one factory, with HF fluorescents on the same circuits to
provide some instant light at switch-on.

Neither is any use if you want instant-on, hence my comment
about PIR usage.

The OP's suggestion of a dusk sensor and timer suggests that instant-on is
not important.

Colin Bignell