🚀 go-pugleaf

In article <fjlIl.34167$fe2.29061@newsfe06.ams2>,
	"ian field" <gangprobing.alien@ntlworld.com> writes:
> Regardless of brand I still find the light quality is not as advertised - a 
> 20W CFL does NOT produce the same light as a 100W incandescent.

At least in Europe, the filament lamp equivalance is completely
misleading. (It's comparing against a softone bulb, which has
a painted coating to give a lower colour temperature, and almost
no one uses those, and they're much less efficient than the
commonly used filament lamps.)

In the UK, just use a 4:1 ratio, so 100W replacement will be a
25W CFL. You can get away with slightly less (e.g. 23W) if the
CFL has an exposed tube (no outer bulb) with well-spaced limbs
(minimum self-shadowing), but this also implies significantly
more bulky than the lamp it replaced, and it might not fit.

Generally, 18W CFLs here are marked as 100W equivalent, and
it's very clear to anyone who's tried them that they don't come
close. For those just trying CFLs for the first time, it gives
a very poor first impression, which in many cases is also the
last impression.

In the case of CFL reflector lamps, the ratio to use needs
reducing to 3:1 or even 2:1 for small ones. (A CFL light source
is particularly inappropriate for use in small reflector lamps.)

In countries with different mains voltage, the ratio may need
adjusting, as filament lamp efficiency varies with the design
voltage. (The most efficient voltage to design a 100W lamp is
about 55V, given a reasonable life requirement, and as you move
the design voltage away from 55V in either direction, the lamp
efficiency drops.)

-- 
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]