That might be down to equivalency expectations. In the UK 20W and sometimes 18W CFLs are sold as being the equivalent to 100W incandescents. Looking at
www.energystar.gov it would appear that on the other side of the pond 100W equivalent means 23-30W.
I can't say I'm surprised to discover this...
Since US runs on a lower voltage (110V as opposed to 230V in UK) their 100 watt bulbs will consume more current (nearly an amp as opposed to half an amp) which means the filiament can be thicker and so run hotter for the same lifetime. A small increase in in temperature means a big increase in visible light output.
But of course, if you try and connect a 110 volt lamp to 230 volt mains, the lifetime drops to some small fraction of the thermal time constant of the filiament.
Previous Topic
Index
