Absolutely not. A lumen is a lumen is a lumen is correct. Or you can use the “equilavent watts” on the packaging of compact fluorescents to equate them to incandescents (27 watts compact fluorescent = 100 watts of incandescent). But for a 40-watt fluorescent tube, each of those equals about 150 watts of incandescent – fluorescents are that much more efficient.
“(screw in flourescent)” only give off more “perceived” light” Oh, my! What is he smoking? This guy may, or may not be competent to install wiring. But he defintely should never design the lighting for any structure.
Replies
what's the equation for candle power/lumen..?
If I had a 1million CP landing light, how many 'lumens' is that, and how many watts equal a CP?
One candlepower equivalent equals 12.57 lumens.
An incandescent source produces about 20 lumens per watt.
You don't have a landing light of 1,000,000 candlepower - that would require an incandescent source to pull about 50,000 amps of 12-volt DC. A Q-beam or other tightly focused beam might have high foot-candles, but that is a measurement of intensity at the illuminated object.
Candlepower and lumens measure the output of the source.David Thomas Overlooking Cook Inlet in Kenai, Alaska
ah-ha..that's what I was missing..the foot candles..I knew something didn't make sense. It's been too long to trust the memory of a landing light power and Q -beam. Thanks.
Go Stab yourself Ya Putz! Ya think I Parked here?
To throw in a little trivia, most commercial A/C landing lights are 28 Vdc or 115 Vac halogen vs. 12 Vdc. (OK -- agree your AK bush pilots mostly operate 12 V systems <G>)
The old incandescent 707 tail light had a 1.2 Vac lamp, any higher voltage and the vibration back there shook any finer filaments to pieces in less than one flight, and the 1.2 Vdc lamp was shock isolated on a 1.2 pound plate to boot. Nowadays, best is LED array or Xenon or similar flash. For instance, the escape lighting system (yes, there is one to get between nodes) on the space station is all strings of LEDs.
To reiterate what everbody said, a watt is a watt is a watt only for total caloric content, integrated over dc to >gamma. Visible light is only a small fraction of that integral.
I thought briefly of getting distingushing between 12- (14.4) versus 24 (28.8) - volt DC systems, but as you said, I have an Alaskan perspective. Super Cubs only have 12-volt systems. If any. Someone trying for a really STOL plane will toss the generator, battery, and starter. Hand prop and let the magneto power the plugs.
DHC-2 Beavers on the other hand. . . . David Thomas Overlooking Cook Inlet in Kenai, Alaska
Your air conditioner has landing lights?!
got so many landing lights at the surplus store EVERYTHoNG here has them<G>.
What if you are burning the candle at both ends?
Do you get half as much light or twice as much?
Mr T
Do not try this at home!
I am an Experienced Professional!
To see how much more efficient fluorescents are, try holding your hand on a 60 W incandescent bulb for 5 minutes? OK, don't try it, but you get the idea.
"To see how much more efficient fluorescents are, try holding your hand on a 60 W incandescent bulb for 5 minutes? OK, don't try it, but you get the idea."
Usually right but not always. Witness the higher efficiency AND higher heat output of halogen bulbs over regular tungsten incandescents. The extra heat output is more than compensated for by higher light output, a result of running the filament at a much higher temperature.
yes
Yaaarg !¡!!¡!!! Stand still... While I smite thee !
quittintime
A watt is a watt is a watt of what? A watt of input is a watt of input. However, the outputs may be rather different. In an incandescent light, most of the output is outside the range of human vision. Thus very little of the watt of input comes out as visible light.
In a fluorescent light, the electricity excites mercury atoms that produce infrared (if I remember correctly) which is then absorbed by the phosphors in the coating on the inside of the glass tube which is then re-radiated as visible light. By picking the right phosphors, the spectrum of light emitted can be made fairly close to that of an incandescent while producing much more visible light and a lot less heat. The general figure I have seen in that fluorescents can be up to 75% more efficient than incandescents. However, fluorescents don't make very efficient heat lamps...
LEDs emit light in a different fashion and I have read that while they are much more efficient than incandescents, they are somewhat less efficient than fluorescents. Haven't seen specific figures, however.
Close, but no cigar. Absolutely, you and others are right that you get DIFFERENT amounts of light from different kinds of lamps, all for the same amount of input power (and hence, operating cost).
A fluorescent bulb is a low-pressure mercury arc lamp, which produces nearly all of its light output in the blinding, sterilizing ULTRAVIOLET, ~ 254 nanometres wavelength. The phospors coated on the inside of the tube absorb this light and emit a range of visible light wavelengths, just like you said. Phosphors of various emission wavelengths are mixed to give the desired colour of visible light output. The initial conversion process from electricity to light in the LP mercury vapour lamp is extremely efficient, and the phosphors are remarkably efficient at converting this UV light to visible light we can use. Efficiency means that these lights generate useful visible light, rather than infrared light- so you're dead right, they're pathetic as heat lamps. But if you're after visible light, the net result of the fluorescent unit's two-step process is far more efficient than heating a wire up until it glows!
Fluorescents are pretty efficient, but the kings of the castle from an efficiency standpoint are the high pressure metal-doped mercury vapour lamps that are used in industrial settings. These suckers are amazingly efficient and produce incredibly intense light- but they take a long time to warm up, and it's not as attractive a light as what you can get from a modern "daylight" fluorescent.
Right you are, and I meant to say that. But my occasionally functional brain was already off thinking about something clever to say about fluorescents not being very effective as infrared heat lamps...
Thanks for the correction.
By the way, do you happen to know the relative efficiency of LEDs vs incandescents and fluorescents?
Edited 2/5/2004 6:34:07 PM ET by CaseyR
I don't, but I know someone who would- and I'll ask them and try to get back to you. The trouble with LEDs is the capital cost per watt of light emitted-not cheap, yet...but some hope of them getting cheap enough to become more widely used. Certainly a good match for solar-driven lighting, where DC generation, DC storage and DC conversion to light make the system pretty cheap and easy and efficient.
Love this board...so many intelligent people in so many different fields!
Moltenmetal mentioned high capital cost of LEDs. Have y'all seen LED traffic lights? Fantastic! Bright enough to see when the sun is shining at the worst angle. They are expensive, but they last five times longer than the old style, meaning fewer service calls and thus lower maintenance costs.
Regards,
Tim
Or flashlights or red flashing bike or running lights...
Who ever invented work didn't know how to fish....
I noticed a while back that the taillights on the busses in Seattle are sometimes led's.
I can peacefully choose, to peacefully do, that which I do not want to do.
I can also peacefully choose, to peacefully not do what I really do want to do.
quittintime
CasyR:"the relative efficiency of LEDs vs incandescents and fluorescents?" My shot from the hip estimate is LED are 50% more efficient. Since compact fluorescent are 3.7-fold better than incandescent and LEDs are about 5 times mroe efficient than incand.
Trimbutcher: "Have y'all seen LED traffic lights?" I think it is more than 5 times the life. All the LED specs I see call for minimum 10,000 hours. Some for 100,000 hours. You're right about the labor saving. An expensive lightbulb is well worth not getting the city guys out there on a cherry picker.
The LED really shine (so to speak) when the environment is tough (water, vibration), if you use batteries, or need the really long bulb life. I've switched to mostly LED headlamps. But for the really bright one, I use a 10-watt, halogen, 12-volt, mini track light and power it from my 12-volt DeWalt batteries.David Thomas Overlooking Cook Inlet in Kenai, Alaska
Traffic light bulbs have a service life of 8-10,000 hours.
http://www.damarww.com/subcategory.asp?sub=114
According this they are expecting to save a typical $600/year per intersection.
http://www.howstuffworks.com/question178.htm
Edited 2/6/2004 2:18:17 PM ET by Bill Hartmann
Bill citation has LEDs as 5 to 6 times as efficient as incandescents. So LEDs are about 50% better than fluorescents, lumens per watt. And a lot tougher.
And the $600/year per intersection is only for electricity. Labor savings would be on top of that.David Thomas Overlooking Cook Inlet in Kenai, Alaska
Exactly right.
From: http://lighting.bki.com/overview/lampattr.htm
LPW = Lumens per Watt - The higher the better. More light less energy.
CRI = Color Rendering Index - How close to true daylight the light is. 100 best.
CCT = The higher the 'whiter' the light.
Lighting Technology Comparison
(Watts)
(LPW)
(Kelvin)
(1000 hr)
(min)
Sodium
Halogen
Notes:
A general rule is that the hotter a light source gets the less efficient it is. Heat is wasted energy. An incandescent bulb should but more properly termed a heat bulb than a light bulb as it onlyconverts something like 13% of the energy used to light. All the rest is converted to heat. Not too much of a problem if you are in heating season but murder if you are running the AC.
This will clear things up.
http://www.abbottandcostello.net/clips/watts.wav
I did that routine onstage at Lake George NY in '73 along with Who's On First. Thanks for that, brought back mucho memories.
A what ?
Yaaarg !¡!!¡!!! Stand still... While I smite thee !
quittintime
"Absolutely not. A lumen is a lumen is a lumen is correct."
Not exactly. There is something to this "Perceived light", but only with fluorsecent types.
Fluorscents out put light in descrete color bands. The color receptors in the eye also work io descrete bands.
The old lights (cool white, warm white) with the simple phosporuses where a poor match with the eye. So while the lamps put out the lumens the eye did not see them.
The newer rare earth, high CRI "look" much brighter becase they better match the eye.
I've got 5 x 27 watts = 135 watts of compact fluorescents in my living room in sconces (therefore indirect) and 8 x 50 = 400 watts of halogen in ceiling cans, 21 feet up. Different qualities of light but simliar in their abilities to light up the whole room. For a 3-fold difference of wattage, even with the fluorescents have an extra surface to bounce off of.
And, side-by-side, I can't tell the sconces with fluorescent (27 watt) versus 100-watt incandescents except for a 0.5 second or less warm-up time. So there's a 3.7-fold difference telling me that watts are not watts.
I hear what you're saying about non-full-spectrum light. But that is a minor factor compared to the different efficiences of different lighting types.David Thomas Overlooking Cook Inlet in Kenai, Alaska