Abdullah Eyles wrote:
Bare in mind, 120V US filament lamps are more efficient than 240V
UK filament lamps, which will make the Incandescent and Tungsten
Halogen tables wrong for UK comparisons.

Also, in the fluorescent lamps sections, US T8 runs at a different
current from rest of the world which will affect the results, and
T12 High-Output doesn't exist outside the US AFAIK. US regular T12
and T8 have higher control gear losses on magnetic ballasts than
220-240V countries, although the table ignores control gear losses.


And I was so pleased with myself... back to the drawing board...

Assuming that this comparison is valid for the UK, its interesting to
note that fluorescent, metal halide, and high pressure sodium all have
similar efficiency which is only half that of nasty yellow low pressure
sodium. The council have just replaced all LPS streetlights near us with
HPS ones that appear a lot brighter, although the light seems to be
focused where its needed much more effectively than the old ones so
perhaps they get by using the same power.