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Old 08-08-2011, 01:17 PM
crad crad is offline
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Join Date: May 2011
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Okay I have a little more time for this one now. If you did not know lighting is one of the means I use to feed my family.
Lighting is a very cool knowledge area to learn. So if you research lighting then you know the 7 colors of the spectrum correct? If not let me help you remember, red, orange, yellow, green, blue, indigo and violet these colors never change order either.
Now some other terms we need to know here are,
1. fluorescent Lamp: A high efficiency lamp utilizing an electric discharge through low pressure mercury vapor to produce ultra-violet (UV) energy. The UV excites phosphor materials applied as a thin layer on the inside of a glass tube which makes up the structure of the lamp. The phosphors transform the UV to visible light.
2. Full Spectrum Lighting: A marketing term, typically associated with light sources that are similar to some forms of natural daylight (5000K and above, 90+ CRI), but sometimes more broadly used for lamps that have a smooth and continuous color spectrum.
3. Kilowatt Hour (kWh): The standard measure of electrical energy and the typical billing unit used by electrical utilities for electricity use. A 100-watt lamp operated for 10 hours consumes 1000 watt-hours (100 x 10) or one kilowatt-hour. If the utility charges $.10/kWh, then the electricity cost for the 10 hours of operation would be 10 cents (1 x $.10)
4. Lumen: A measure of the luminous flux or quantity of light emitted by a source. For example, a dinner candle provides about 12 lumens. A 60-watt Soft White incandescent lamp provides about 840 lumens.
5. Lumen Maintenance: A measure of how well a lamp maintains its light output over time. It may be expressed numerically or as a graph of light output vs. time.
6. Lumens Per Watt (lpW): A ratio expressing the luminous efficacy of a light source.
7. Typical lamp efficacies:
• Thomas Edison's first lamp — 1.4 lpW
• Incandescent lamps — 10-40
• Halogen incandescent lamps — 20-45
• Fluorescent lamps — 35-105
• Mercury lamps — 50-60
metal halide lamps — 60-120
• High-pressure sodium lamps — 60-140
8. note: The values above for discharge lamps do not include the effect of the ballasts, which must be used with those lamps. Taking ballast losses into account reduces "system" or lamp-ballast efficacies typically by 10-20% depending upon the type of ballast used.
9. Mean Lumens: The average light output of a lamp over its rated life. Based on the shape of the lumen depreciation curve, for fluorescent and metal halide lamps, mean lumens are measured at 40% of rated lamp life. For mercury, high-pressure sodium and incandescent lamps, mean lumen ratings refer to lumens at 50% of rated lamp life. See Lumen Maintenance.
10. Power Factor (PF): A measure of the phase difference between voltage and current drawn by an electrical device, such as a ballast or motor. Power factors can range from 0 to 1.0, with 1.0 being ideal. Power factor is sometimes expressed as a percent. Incandescent lamps have power factors close to 1.0 because they are simple "resistive" loads. The power factor of a fluorescent and HID lamp system is determined by the ballast used. "High" power factor usually means a rating of 0.9 or greater. Power companies may penalize users for using low power factor devices.
11. Rated Lamp Life
For most lamp types, rated lamp life is the length of time of a statistically large sample between first use and the point when 50% of the lamps have died. It is possible to define "useful life" of a lamp based on practical considerations involving lumen depreciation and color shift.
12. Watt
A unit of electrical power. Lamps are rated in watts to indicate the rate at which they consume energy. See Kilowatt Hour.

Couple of pet peeves here, please recycle your florescent lamp including cfl’s they contain the same amount of mercury that t-8 lamps do.
Okay now for the whole issue I started here.
I chose 8000k because they are the best full spectrum bulb I could buy in a T-8 bulb. I have peppers in bloom and peppers being produced. They are horizontally and as pointed out the light is wrong for the tomatoes I believe I need to put them vertically and am in the process of that. I also am going to include some red, orange, yellow, green spectrum on them in the form of a CFL lamp in a heat lamp assembly shining directly on the tomatoes. I am looking for a 2700 to 4100k (red 2700, orange 3000, yellow3500, green 4100) bulb with a CFL rating of 50 plus watts. Now you are starting to run up costs.
Now HID is upfront expensive plus spectrum dependant on a specific bulb. Their lumen maintenance is quicker then florescent a whole other issue. So once your lights reach that 50% area they need to be replaced as you are paying full price for a light giving 50% of its capability we will not be able to tell it with out a meter but our plants will. Now as our lamps decrease so does our color rendering and our lumen output but our operating costs stay the same as when they were new. I threw the power factor in there for your mathematical consideration as it is a factor on your power bill.
I have put this out there for your personal use and I hope it helps you in choose the correct lighting for your growing needs. I will touch on led lighting at a different time.

Last edited by crad; 08-08-2011 at 01:27 PM. Reason: edited for color and grammar.
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