I've bought this GE/Jasco 55w 2D fluorescent fixture. The fixture is not as
advertised because the package states "five 60w bulbs" is incorrect. The
dome is too thickly frosted to achieve that claimed light output. Whoever
designed this fixture must have went by the raw lumen output of the
fluorescent tube, and probably never tested the actual fixture with the dome
in place. I've contacted GE, but they say "contact Jasco". So I contact
Jasco. Either the person responding to my email doesn't understand this, or
they don't care. In short, Jasco says: "We can't make the bulb brighter, so
just bring it back." ???? So of course I try to explain it to them again,
not the BULB but the DOME is the problem. Either make the dome less thickly
frosted, and/or at least fix the wattage claim on the box. I like the
fixture, except the lower than claimed output is a little disappointing.
What method of measuring the light output did you use? Eyeball.
Tilting at Windmills was fun when I younger and less informed. Best of luck
getting them to change. I have some political issues with the President of
the USA I could send you if you need something else to do.
This is a common complaint of compact fluorescents.
I would take light output claims exceeding that of known
available incandescnts (including incandeascents with rated life as low
as 750 hours) of as low as 2.5 times the claimed power consumption with
skepticism in addition to at least a grain of salt, and claims of
producing more light than an incandescent of about 3.5-4 times the claimed
power consumption with at best "hostile skepticism".
Producing same light as an incandescent of 1/4 the claimed power
consumption is easier, due to a few various "economies of scale" that
favor higher efficiency of higher wattage lightbulbs. However, even good
brand/model compact fluorescents in good conditions only produce about as
much light as better incandescents of 4 times their nominal wattage.
For example, I have found the best 13-15 watt compact fluorescents
generally to fail to significantly outshine the brightest 120V 60 watt
incandescents, and I have found them more noted to fall short of "60 watt
incandescent equivalence" than to exceed such. You may sometimes need a
compact fluorescent of wattage in the 18-20 watt range to produce as much
effectively usable light as a 60 watt incandescent, and in more extreme
adverse cases require 23-25 watts of compact fluorescent wattage to get
you as much useful light as a 60 watt incandeascent.
And beware - recessed ceiling fixtures are a bad case, harder on
"screw-in" (ballast-included-in-"bulb") compact fluorescents of wattage
more than 20 watts, and ones as low as 15 watts get to claim something
special about being rated to survive the heat endured in recessewd ceiling
fixtures. (HINT: Compact fluorescents do not produce much infrared,
produce more non-radiant heat [materializing in the fixture as opposed to
elsewhere in the room] than incandescents of same wattage, heat up
fixtures as much as incandescents of about 1.5 or more times as much
wattage, and tolerate high tem,peratures less than incandescents do!)
Not only do ceiling fixtures, especially recessed ones, as well as small
enloclosed fixtures compromise the life of many compact fluorescents and
most of ones of wattage over about 13-15 watts and probably nearly all of
wattage over 20 watts, this can compromise light output, color of the
emitted light, and color rendering properties of the emitted light.
In a somewhat bad case, I have seen an installation (visiting many
dozens of times night and day) of apparently 13 watt quadtube units in
recessed ceiling downlights where the light output of each I have never
estimated to significantly exceed that available from 40 watt "standard"
I do encourage usage of compact fluorescents, but I do warn that they
have some "pitfalls"!
- Don Klipstein ( firstname.lastname@example.org, http://www.misty.com/~don/cfx.html )
I have seen "in my experience" that compact fluorescent recessed ceiling
"downlights" in commercial buildings tend to use lamps ("bulbs) that do
not have built-in ballasts, as in the "bulbs" are not screw-in type and
that the necessary ballasts are separate from the "bulbs", presumably at
least somewhat removed from the heat produced by the lamps/"bulbs".
- Don Klipstein ( email@example.com)
On Tue, 07 Jun 2005 23:46:11 GMT, firstname.lastname@example.org (JM)
Not only can't Jasco make the lamp (what you call the bulb) brighter,
but they are not going to make a new dome just for you. If you don't
like the fixture your only option is to bring it back.
Now, let's take a look at the fixture manufacturers claims.
The GE 55-watt 2D lamp is rated at 4000 lumens after 100 hours
(Initial Lumens) and 3400 Mean Lumens (that is after 40% of rated
The light output of 120-volt 60-watt incandescent lamps vary with
design life, type of diffusing coating, and a few other factors . I
would say that the GE Model 60A, which is a 120-volt, 60-watt,
1000-hour, A-19 lamp with conventional diffusing coating (not Soft
White) is a good example of a "standard" incandescent lamp. This lamp
is rated by GE for 856 initial lumens.
So, based on initial bare lamp lumens only, the 55-watt 2D would be
equivalent to 4.62 of these 60-watt incandescent lamps. However, based
on mean lumens, the 55-watt 2D is equivalent to only 3.93 of these
60-watt incandescent lamps. (Your evaluation took place with a new
55-watt 2D lamp, so the mean lumen issue is not relevant to your
But as you have stated, bare lamp lumens are not the whole story. The
fixture must be designed to get the light produced from the lamps out
of the fixture and on to the work surface. This involves not only the
diffuser (dome) but also the reflector. I agree with your conclusion
that the manufacturer's claim is based on the light produced by the
55-watt 2D lamp, with a bit of exaggeration thrown in, and not the
light out of the fixture.
You might compare the bulb to a 60 W bulb using Bunsen's 1844 "grease spot
photometer"... move a 1" grease spot on a piece of white paper between the
bulbs until the spot disappears, which indicates the intensities are the
same at the card. The bulb brightness ratio is the square of the ratio of
the distance from the card to each bulb...
On 8 Jun 2005 15:17:29 -0400, email@example.com wrote:
We are interested in lumens not brightness. And, since the size and
shape of the lamps in question are very different, we need to use an
instrument more sophisticated than a grease spot photometer. In this
case an integrating sphere or a goniometer will give lumen output
independent of shape..
Actually, we don't give a fuck.
In the past, we have always found that when we bought a light fixture
that didn't turn out to be what we thought, we took it back to the
We most cetainly did not call the manufacturer(s) like some sort of
psycho nutjob, demanding that they put some lumens in a box and ship
them to us.
No, I didn't say that. I'm looking for general changes, that's all. But
judging from Jasco's responses, they don't care. For some of you trolls from
misc.consumers bringing it back isn't going to do squat. Jasco doesn't care.
They aren't going to change a thing. What would it take for them to change:
federal intervention? Millions of returns? Unfortunatly, that's the way the
world is run today. Money comes first.
Perhaps the size and shape don't matter much, if the bulbs (vs fixtures)
are far away from the spot. For non-isotropy (if any), we might put each
in a 5-sided box (a sphere :-) lined with foil with the open sides aimed
at the spot.
What's a goniometer? Sounds potentially painful.
On 9 Jun 2005 05:01:16 -0400, firstname.lastname@example.org wrote:
I agree that if you are far enough away that both sources can be
approximated by point sources and a grease spot photometer might work,
except for the fact that the output of the 2D has a significant
directional component due to the fact that the lamp is almost flat.
You pseudo-sphere sounds like a good idea :-)
Only painful if you are standing in the wrong place when it is
I should have used the term gonio-photometer since "goniometer" is a
more general term that applies to objects that can be rotated around
all three axis, but sometimes to objects that only rotate around one
axis, such as a variable angle protractor.
The lighting industry uses the shorthand term "goniometer" to refer to
a gonio-photometer. I have argued in this forum against using
well-defined words incorrectly, so I will refrain from using
goniometer to refer to a gonio-photometer from now on.
A gonio-photometer is a detector on an arm of fixed length that can
move completely around a light source. The gonio-photometer is
installed in a room with flat black walls so there is no reflected
light, only the direct light from the lamp or luminaire, depending
upon what you are measuring. The detector mounted on the end of the
arm collects light from the source falling on a virtual sphere
surrounding the source and therefore gives lumens when the data is
processed. You also get the light distribution at the same time.
For an example of a gonio-photometer you can see:
This version uses a mirror on the arm to reflect light to a fixed
sensor, and mounts the source on a rotating table so the arm only
moves in a 180 deg arc, but the concept is the same.
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