Pablo wrote:

The Screwfix catalogue says that Low Voltage Halogen Spot Lights use less
energy than mains voltage. How can this be? Do they defy the laws of
Physics? 50w at 12V uses the same energy as 50w at 240V.




The more robust filaments run at higher temp than a mains one can, and
the scinece sez that hotter bodeies will emit at shorter wavelength.

97% of normal bulb is emitted in infra red - its heat. LV halogens are a
bit better - say only 95%. So more light per 50W in etc.