Lighting principles

Energy Efficient Lighting

The quantity and quality of LIGHT around us determine how well we see and work. Light affects our health, safety, morale, comfort, and productivity.Lighting also directly affects our economy. In general, We spend about one-third of our (electricity) budget on lighting. Technologies developed during the past 10 years can help us cut lighting costs 30% to 60% while enhancing lighting quality and reducing environmental impacts.
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Lighting Principles and Terms

Illumination

A lumen is a measurement of light output from a lamp, often called a tube or a bulb. All lamps are rated in lumens. For example, a 100-watt incandescent lamp produces about 1750 lumens. It is printed on the lamp. The distribution of light on a horizontal surface is called its illumination. Illumination is measured in footcandles or lux. A footcandle of illumination is a lumen of light distributed over a 1-square-foot (0.09-square-meter) area. A lux of illumination is a lumen of light distributed over 1-square-meter area. The amount of illumination required varies according to the difficulty of a visual task. The Illuminating Engineering Society says that illumination of 30 to 50 footcandles is adequate for most home and office work. Difficult and lengthy visual tasks.like sewing for extended periods of time.require 200 to 500 footcandles. Where no seeing tasks (i.e., tasks whose speed and accuracy of completion are affected by quality and quantity of light) are performed, lighting systems need to provide only security, safety, or visual comfort.requiring from 5 to 20 footcandles of illumination. Another lighting term you will hear is efficacy. This is the ratio of light output from a lamp to the electric power it consumes and is measured in lumens per watt. It indicates the efficiency of the light.

Light Quality

Light quality describes how well people in a lighted space can see to do visual tasks and how visually comfortable they feel in that space. Light quality is important to energy efficiency because spaces with higher quality lighting need less illumination. High-quality lighting is fairly uniform in brightness and has no glare. For example, direct intense sunlight streaming through the windows of a room with chocolate brown carpets and dark wall paneling will likely give too much contrast in brightness. On the other hand, in a pale-colored room bathed in soft light, you can hardly tell where the light is coming from because no one area of the room appears much brighter than another. The walls, ceiling, floor, and work surfaces are relatively the same light hue.

Glare

Eliminating glare (i.e., excessive brightness from a direct light source) is essential to achieving good lighting quality. Suitable shades, fittings shall be used.

Light Color and Color Rendering

Lamps are assigned a color temperature (according to the Kelvin temperature scale) based on their "coolness" or "warmness." The human eye perceives colors as cool if they are at the blue-green end of the color spectrum, and warm if they are at the red end of the spectrum.Cool light is preferred for visual tasks because it produces higher contrast than warm light. Contrast is the brightness difference between different parts of the visual field, which is the expanse of space you can see at a given instant without moving your eyes. Warm light is preferred for living spaces because it is more flattering to skin tones and clothing (especially in cold countries- and not in southern states of India).Keep in mind, though, that artificial light sources vary widely in their color rendering indexes (CRI). The CRI is a measurement of a light source's ability to render colors the same as sunlight does. For example, incandescent lamps are rated at a CRI of 100.nearly equal to sunlight.while some high-pressure sodium lamps have a CRI of 22, which means they render colors very poorly.

Types of Lighting

There are four basic types of lighting: incandescent, fluorescent, high-intensity discharge, and low-pressure sodium.

Incandescent ( in general our bulbs)

Incandescent lamps are the least expensive to buy but the most expensive to operate. Incandescent light is produced by a tiny coil of tungsten filament that glows when it is heated by an electrical current. Incandescent lamps have the shortest lives ( 500-1000 operating hours) of the common lighting types. They are also relatively inefficient compared with other lighting types.

Tungsten halogen

This newer type of incandescent lighting achieves better energy efficiency than the standard A-type bulb. It has a gas filling and an inner coating that reflect heat. Together, the filling and coating recycle heat to keep the filament hot with less electricity. These lamps are considerably more expensive than standard incandescents and are primarily used in commercial applications: theater, store, and outdoor lighting systems.

Reflector lamps

Reflector lamps (Type R) are designed to spread light over specific areas. They are used mainly indoors for stage/theater and store applications, as well as floodlighting, spotlighting, and downlighting.

Fluorescent ( common Tube lights and CFL)

The light produced by a fluorescent tube is caused by an electric current conducted through mercury and inert gases. Fluorescent lighting is used mainly indoors and is about 3 to 4 times as efficient as incandescent lighting. Fluorescent lamps last about 10 times longer than incandescents. But, to gain the most efficiency, you should install fluorescents in places where they will be on for several hours at a time.Fluorescent lights need ballasts (i.e., devices that control the electricity used by the unit) for starting and circuit protection. Ballasts consume energy. You can increase the energy savings for existing fluorescent lighting by relamping (e.g., replacing an existing lamp with one of a lower wattage), replacing ballasts, and replacing fixtures with more efficient models.

Tube fluorescent

The two most common types are 40-watt, 4-foot (1.2-meter) lamps and 75-watt, 8-foot (2. 4-meter) lamps. Tubular fluorescent fixtures and lamps are preferred for ambient lighting in large indoor areas because their low brightness creates less direct glare than do incandescent bulbs.

Compact fluorescent

Compact fluorescent lamps (CFLs) are the most significant lighting advance developed for homes in recent years. They combine the efficiency of fluorescent lighting with the convenience and popularity of incandescent fixtures. CFLs can replace incandescents that are roughly 3 to 4 times their wattage, saving up to 75% of the initial lighting energy. Although CFLs cost from 10 to 20 times more than comparable incandescent bulbs, they last 10 to 15 times as long. This energy savings and superior longevity make CFLs are one of the best energy efficiency investments available.

High-Intensity Discharge

High-intensity discharge (HID) lamps provide the highest efficacy and longest service life of any lighting type. They are commonly used for outdoor lighting and in large indoor arenas. HID lamps use an electric arc to produce intense light. They also require ballasts, and they take a few seconds to produce light when first turned on because the ballast needs time to establish the electric arc. The three most common types of HID lamps are mercury vapor, metal halide, and high-pressure sodium. HID lamps and fixtures can save 75% to 90% of lighting energy when they replace incandescent lamps and fixtures. Significant energy savings are also possible by replacing old mercury vapor lamps with newer metal halide or high-pressure sodium lamps. Mercury vapor.the oldest type of HID lighting.is used primarily for street lighting. Mercury vapor lamps provide about 50 lumens per watt. They cast a very cool blue/green white light. Most indoor mercury vapor lighting in arenas and gymnasiums has been replaced by metal halide lighting, which has better color rendering and efficiency. Metal halide lamps are similar in construction and appearance to mercury vapor lamps. The addition of metal halide gases to mercury gas within the lamp results in higher light output, more lumens per watt, and better color rendition than from mercury gas alone. Metal halide lamps are used to light large indoor areas such as gymnasiums and sports arenas, and for outdoor areas such as car lots or anywhere that color rendition is important. High-pressure sodium lighting is becoming the most common type of outdoor lighting. It provides 90 to 150 lumens per watt.an efficiency exceeded only by low-pressure sodium lighting. High-pressure sodium lamps are also reliable and have long service lives. Their color is a warm white, and their color rendition ranges from poor to fairly good depending on design and intended use.

Low-Pressure Sodium

Low-pressure sodium lamps work somewhat like fluorescent lamps. They are the most efficient artificial lighting, have the longest service life, and maintain their light output better than any other lamp type. Low-pressure sodium lighting is used where color is not important because it renders all colors as tones of yellow or gray. Typical applications include highway and security lighting.

Energy Efficiency with Lighting

In a typical residential or commercial lighting installation, 50% or more of the energy is wasted by obsolete equipment, inadequate maintenance, or inefficient use. Saving lighting energy requires either reducing electricity consumed by the light source or reducing the length of time the light source is on.

"Relamping" means substituting one lamp for another to save energy. You can decide to make illumination higher or lower when relamping. But be sure that the new lamp's lumen output fits the tasks performed in the space and conforms to the fixture's specifications.

Relamping incandescent fixtures

Example, for energy savings of 60% to 75%, many incandescent lamps can be replaced by CFLs. In general , a 60 W bulb can be replaced with 11 W CFL. In selecting CFL: Take from an accepted dealer or shop, commonly known make in India, integral Ballast (choke) is better, if pin type, select 4 pin type. BIS mark in choke is a mark of approval for the choke. Electronic ballast consumes 2-4 W while electro-magnetic choke takes 6-10 W. If electronic ballast , check the symbol (H) which indicates low harmonic distortion.

Relamping fluorescent fixtures

Common 40-watt and 75-watt lamps can be replaced with energy-saving lamps of 34 watts and 60 watts, respectively. Energy-saving lamps for less-common fluorescent fixtures are (26 W retrofit) also available. If you need to replace the ballasts in your fluorescent fixtures, consider using one of the improved varieties. The new electromagnetic ballasts reduce ballast losses, fixture temperature, and system wattage. Because they operate at cooler temperatures, they last longer than standard electromagnetic ballasts. Electronic ballasts operate at a very high frequency that eliminates flickering and noise. They are even more efficient than improved electromagnetic ballasts. Some electronic ballasts even allow you to operate the fluorescent lamp on a dimmer switch, which usually is not recommended with most fluorescents. Check the symbol (H) which indicates low harmonic distortion

Improving Lighting Controls

Lighting controls are devices for turning lights on and off or for dimming them. The simplest type is a standard snap switch. Other controls are photocells, timers, occupancy sensors, and dimmers.

· Snap switches, located in numerous convenient areas, make it easier for people in large, shared spaces to turn off lights in unused areas.
· Photocells turn lights on and off in response to natural light levels. Photo-cells switch outdoor lights on at dusk and off at dawn, for example. Advanced designs gradually raise and lower fluorescent light levels with changing daylight levels.
· Mechanical or electronic time clocks automatically turn on and off indoor or outdoor lights for security, safety, and tasks such as janitorial work.
· Crank timers, which are spring-driven and similar to old oven timers, limit lights to short durations where the need for light is brief.
· Occupancy sensors activate lights when a person is in the area and then turn off the lights after the person has left. They are popular for areas used infrequently, such as warehouses. They also offer security advantages over continuous lighting: when lights suddenly come on, they startle intruders and alert residents and neighbors to motion in the area.
· Dimmers reduce the wattage and output of incandescent and fluorescent lamps. Dimmers also increase the service life of incandescent lamps significantly. However, dimming incandescent lamps reduces their lumen output more than their wattage. This makes incandescent lamps less efficient as they are dimmed. Dimming fluorescents requires special dimming ballasts and lamp holders, but does not reduce their efficiency.

Daylighting

Daylighting means using daylight for indoor lighting. Modern buildings designed for daylighting typically use 40% to 60% less electricity for lighting needs than do conventional buildings. Sunlight and daylight are free and readily accessible.( During a sunny day at noon, light levels at different places- open lawn- 30000 lux or above, a class room with windows open - 400 lux, with windows closed- 160 lux. With 4 tube lights ON in the night-100 lux.

POLLUTION from Fluorescent Lamps

All fluorescent lights contain small amounts of mercury, and short-lived radioactive material. Because of these hazardous materials, you should not dump burned-out lamps into the yard. Mercury, antimony, chromium, lead all will ooze out into the drinking water-well,river,pond etc. which is dangerous. Dispose of them with other household hazardous wastes such as batteries, solvents, and paints at your community's designated drop-off point for proper disposal by the panchayat or corporation Light from fluorescent lamps without proper radiation shield contain a very small % of UV rays harm full to eyes. Do not use Tubes/CFL without proper shields.

Lighting Maintenance

Maintenance is vital to lighting efficiency. Light levels decrease over time because of aging lamps and dirt on fixtures, lamps, and room surfaces. Together, these factors can reduce total illumination by 50% or more, while lights continue drawing full power. The following basic maintenance suggestions can help prevent this.

· Clean fixtures, lamps, and lenses every 6 to 24 months by wiping off the dust. However, never clean an incandescent bulb while it is turned on. The water's cooling effect will shatter the hot bulb.
· Replace lenses if they appear yellow.
· Clean or repaint small rooms every year and larger rooms every 2 to 3 years. Dirt collects on surfaces, which reduces the amount of light they reflect.
· Consider group relamping. Common lamps, especially incandescent and fluorescent lamps, lose 20% to 30% of their light output over their service life. Many lighting experts recommend replacing all the lamps in a lighting system at once. This saves labor, keeps illumination high, and avoids stressing any ballasts with dying lamps.

Building an HPS system

Building and buying an HPS system
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Introduction

Lighting is a very important component of your grow. You could have the best genetics, the perfect growing space, and tons of knowledge, but without adequate lighting, your grow will simply not perform. This article is not in any way designed to dissuade a person from using fluorescents or MH. This faq is a guide for those that would like to know more about HPS lighting systems and how to buy, assemble, and use them. Pre-assembled HPS lighting systems can be expensive. Most of the cost is overhead and labor. If you were to buy the components separately and put it together yourself, you can save hundreds of dollars with only a small amount of quality sacrifice. Also, when you build it yourself, you have a wider range of products to choose from, so you can build a system that is right for your situation.

Planning

The first step in building a system is to know exactly how much light you need for your area. This FAQ will give you an idea of what you will need to buy: ********

Parts required:
· ballast w/ igniter and capacitor
· socket
· bulb
· extension cord w/ ground wire

OPTIONAL
· reflector
· ballast case
· air-cooling

TOOLS
· screwdriver
· wire cutters and strippers
· wire nuts
· electrical tape

Obtaining parts

To begin on your quest you will need to shop around places in order to find the best deals. You can order the parts you need from the Internet, or you can buy them at a local electrical store. We will discuss Internet purchasing later on. Many of you that live in larger cities will be able to call around to many electrical stores that will carry HPS ballasts and do some comparison shopping. Those in smaller cities might not have a great selection. If you look in the phone book under electrical suppliers, you will see wholesale and retail suppliers. You can get prices from both, but when you call the wholesale store, you will have to ask them if you can buy without an account. Going with the wholesale store will most likely be the cheapest, as they will have many types of ballast in stock. It is important that you ask them if you can buy them individually. Also, you will need to know exactly what you want. You can buy 70 and 150w HPS at Lowe’s or Home Depot, so I am going to concentrate more on 200w and up. The available wattages are 200, 250, 400, 430, 600, and 1000. You will need to determine what voltage you are going to be using (household current in the US is 120v). It is very important that you buy a ballast kit that is compatible with the voltage in your house. Most places will sale multi-tap ballasts which have higher voltages along with the standard 120v. This will probably be your best bet.

From store:
· Pay in cash, nothing with your name on it (no paper trail) · Act calm and confident. If you act shady, they might report your license to the authorities.

Know what you are going to buy before you get there, so you can just walk up and ask for it.
For my example, we will put together a 400w HPS lighting system: (example prices)

· ballast (400w includes igniter and capacitor) $69.29
· porcelain mogul socket $13.20
· bulb (There are many different bulbs, each with different spectrums. This is a cheap bulb) $16.15
· 20' extension cord (length will vary) $8.00
· wire nuts and electrical tape (estimate) $4.00)

TOTAL: $110.44

Accessories. Reflectors are not necessary, but even a cheap batwing style reflector will benefit you by directing the light where you want it. Ballast boxes are also not necessary, but having one reduces the risk of electric shock, burning, and fire.

Optional parts

· reflector(batwing) $30.37
· batwing reflector $21.67 TOTAL: $52.04

Grand total: $162.48 + shipping

The items listed above will give you a fully functional HPS system that is much like one that you can buy. If that price is too high, the reflector and ballast box are expendable. You can make your own reflector and you can mount the ballast on just about anything that can take screws. Doing so, introduces the risk of you touching the ballast components and getting burned or shocked. As long as caution is exercised, you have nothing to worry about.

Additional Options

Air-cooling is another option that people would like to look into more often. Having separate ventilation for your lights will ultimately benefit you as you will have more head room for your plants to grow and the temperature will be greatly reduced. There are 2 method of obtaining an air-cooled reflector/hood:

1) You can build your own using: · This FAQ on how to build an air-cooled hood, with integrated carbon scrubber, and light trap (for the true DIYer) · This FAQ on how to build a cool tube *recently updated Note: If you are going to make the cool tube from above, you can hang the cool tube assembly underneath a stationary reflector, which can either be homemade or manufactured.
2) You can buy a complete air cooled hood online, or at hydro stores

Assembly

Now that we have all the parts that we need, we need to wire up the ballast and assemble the light together. I will point you to this FAQ that taught me how to wire my first ballast.

Connector plugs

A good way to connect the socket to the ballast is to install a set of connector plugs between the ballast and the socket. This will enable you to disconnect and move the light without having to disturb your wiring. Also, you can locate the ballast in another area as to keep heat down in you grow area. Take a 10' - 15' extension cord and cut it into 2 lengths. The shorter one should be the male end (the one with the prongs) and the longer one should be the female (the one with the holes). You will probably want to have the shorter one be around one foot long. It is the piece that is going to be connected to the socket/bulb assembly. The longer piece will need to be long enough that it can reach the other piece of cord from wherever you are going to place the ballast.

Note: We attach the ballast to the female side in order to reduce danger of electric shock. In a rush to pull apart the set up, a person might leave the ballast on and accidentally touch the prongs on the wire. Trust me; you don't want to get shocked by a ballast of any wattage. Connect the white wire from the male end of the extension cord to the white wire of the socket. Connect the black wire of the extension cord to the black wire of the socket. Connect the green wire, if you bought a socket that has a grounding terminal. You will want to connect the female plug to the ballast. Connect the white or COM wire that is coming out of the igniter to the white wire of the extension cord. Connect the black wire from the extension cord to the RED or X2 wire coming from the igniter. You can also connect the green (ground) wire to the same place that you grounded your ballast.

Additional Information

· Remember not to spray water on or near an exposed HPS light bulb, especially when its on (foliar feeding may cause the bulb to explode if water touches the bulb)!
· Do not look directly into the HPS for any amount of time. If you are going to be in your grow room for a long amount of time, wear sunglasses
· Do not touch an HPS bulb while it is hot
· Do not touch an HPS ballast while it is hot
· Replace your lights every 10000 to 15000 hours

Grow light FAQ

Grow light FAQ
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The purpose of this FAQ is to help limit the spread of misinformation regarding effective artificial lighting systems, and help those who choose to grow plants under artificial lighting make an informed decision before buying a lamp. Most of the information contained in this FAQ comes from printed sources, and some from electronically distributed files. Very little comes from my own experience, as I have not owned, used or examined most of the systems discussed here. This FAQ is not going to tell you how to use your lamp, that information can be found in most grower's guides.

Introduction:

There are three major types of lighting systems available right now: incandescent, fluorescent, and high intensity discharge. Incandescent lights are horribly inefficient (especially the screw-in grow bulb type) and really not an acceptable option for plant growth. Although they are inexpensive to purchase, their cost of operation makes them the costliest source of light.

Florescents:

Until the early 1980's most indoor growers used fluorescent lights to illuminate their garden. These tubes have tremendous advantages over incandescents. They emit about 3 times as much light as an incandescent (given the same wattage), and the light spectrum is one that plants con use more effectively. However, they do certainly have their limitations. Light is emitted over a large area, so it is not concentrated. Because of this, the lights have to be hung very close to the plants, and constantly moved to accommodate plant growth. This makes garden maintenance rather difficult. Florescents are, however, very useful in cloning, and starting seedlings. Because in these stages, a plant is not growing vertically very quickly, the disadvantages of moving the lights are reduced. They also put out a more gentle light than the HID lamps, and release less heat. If you choose to use florescents, it is best to purchase the 'cool white' variety. The ones that are sold as grow lamps (including grow-lux, vitalite, etc.) are much less efficient than a standard fluorescent, and just do not put out enough light to be useful. The slightly different spectrum produced by these lamps does nothing for most plants.

High Intensity Discharge Lamps (HID's)

High intensity discharge lamps are easier to use, and more efficient. Low wattage HIDs are sometimes sold for household outdoor use. Large Wattage lamps are used for lighting streets, parking lots, stadiums and other large areas. They come in two basic flavors:

METAL HALIDES or MH lamps emit a white light that looks slightly bluish. They are used to light stadiums, convention centers, gymnasiums, and other large areas where a natural looking light is desired.

HIGH PRESSURE SODIUM or HPS lamps emit a pink or amber light. They are used for lighting parking lots and other areas where the color of the light is not important. HPS units are much more efficient than MH ones, producing more light and less heat per watt of energy consumed. They are often used alone with no detrimental effect on the plants, and will promote faster plant growth than MH lamps during both vegetative growth and flowering. Combinations of bulbs are NOT required, as the HPS lamp does produce all of the light spectrums necessary for healthy growth. MH lamps are available in 175,200, 400 and 1000 watt sizes. HPS lamps come in 50, 75, 150, 400 and 1000 watt sizes. Each lamp requires its own ballast, which comes with the fixtures that are designed to use these lamps, and are also available separately.

The following chart shows how much light each lamp emits, and the area that it covers adequately:

Lamp # of Lumens Sq. Ft 4'FL

(CoolWhite-40W) 2,960 1-2
8'FL (CoolWhite-75W) 5,800 2-4
MH 175W 14,000 5-10
MH 400W 40,000 12-20
HPS 70W 7,600 3-6
HPS 150W 16,000 6-11
HPS 400W 50,000 15-30

Gardens should receive 1000-3000 lumens per square foot. Successful gardens usually are lit at around 2,000 lumens per square foot. During the vegetative stage, plants stretch out when they receive low levels of light. During flowering, the flowers are looser and sparse. So what is the best lamp for growing? It depends on your budget. HPS lamps are by far the best overall, but they are also the most costly to purchase and setup (although some less honest growers have a tendency to steal them from college campuses and the like). However, they are the cheapest to operate, and the utility savings does eventually add up. A quick warning: At least in the US, there are large government agencies whose only purpose is to eliminate the growth of marijuana. Although purchasing a high powered lighting system does not mean that you will be growing pot (and many people grow other things artificially), it is still not a really good idea to link your name with the purchase of one of these lamps (especially the larger ones). 1) Order online with someone elses credit card (person with no record, like Granny), and have the items delivered to a squeaky clean house. Wait a while before picking the stuff up. 2) Or go into the store knowing exactly what you want, pay for it in cash, and do not give them your name (or give them a false one if they even ask). Most lighting distributors will not ask any questions.

Light disagreement

Do metal halide lamps grow stonier buds?
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I have to disagree with you about lights. I've been growing under metal halides (MH) lamps for more than 20 years. In CC issue #34 you stated that MH lamps are useful only when the amber light of a high-pressure sodium (HPS) lamp would cause a problem. My associates and I would disagree. The consensus among us is that HPS lamps produce more weight, but the stoniest, longest-lasting high comes from metal halide lamps. Ultra-violet (UV) light is the key. MH lamps produce more than HPS lamps and the more UV, the higher the potency climbs in normally high potency plants. I grow for buzz, not weight, or you could say for love, not money, so the MH lamps suit my purpose. I use a Sunmaster MH lamp. The plants produce a little more weight under them than the old 5500K (Color temperature) bulbs, but they've kept the UV light strong.

The article that you refer to, Pot Potency by DMT, discusses the environmental aspects of THC production. In the same issue, I recommended HPS rather than MH lamps. One of the factors that DMT covered was ultraviolet light. There are three spectrums of UV light. UVA is the least harmful. This is the spectrum produced by black lights. UVC light is dangerous to all life. It is used in water purification systems to sterilize water. The light spectrum of interest to us is UVB. It affects life in many ways. In humans it causes tanning, skin aging, eye damage and cancers. Other animals are affected by it in all sorts of ways. The Earth's atmosphere filters UVB light. There is more UVB light at high altitudes than at sea level. Also, sunlight at the equator takes the shortest route through the atmosphere. As the latitude increases, sunlight reaches Earth after going through more atmosphere because of its slanted path. Therefore UVB at the equator is much more intense than in temperate zones. That's one reason people tan or burn so fast in the tropics, and why skin cancer rates are higher in southern than northern states. A researcher conducted a controlled experiment in a greenhouse. He lit a group of high potency plants similarly except with the addition of UVB light to some groups. He found that the percentage of THC increased in a direct ratio with the increase in UVB light. This research confirms the adage that high altitude plants are more potent than those grown at low altitudes. If you look at old-world land races of cannabis, plants that have become adapted to the climate and latitude, the ratio of THC to CBD starts at 100 : 1 at the equator. At the 30th parallel (The Hindu-Kush Valley) the plants have a ratio of 50 : 50. At the 45th parallel the ratio is near 1 : 100. This corresponds roughly with the amount of UVB light received at these latitudes. There is much more UVB at the equator than the 45th parallel. How can you get more UVB light to your plants? Certainly it's true that MH lamps emit more UVB light than HPS lamps. Still the amount that MH lamps emit is small. In fact, many manufacturers use UVB shielding glass to filter out most of the UVB that's produced. The UVB light the plant receives from an MH lamp does increase the plant's potency slightly at the cost of yield, but there are better ways to introduce UVB light into the grow room. They include reptile lights, which emit about 10% UVB, and tanning lamps. The problem with using these lamps is that they are associated with increased number of cancers and many other problems. They should not be on when you are in the grow room. Not much research has been conducted on using them to produce higher THC values. I will do a full report in a future issue.

Ballast information

Does the bulb have to match my ballast?
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Yes Ballasts and Bulbs Should be Matched. HID bulbs generally need specific ballasts, and any given ballast can usually safely and effectively operate only one type or a few types of HID bulbs. The bulb wattage must be matched to the ballast. A smaller bulb will usually be fed a wattage close to what the proper bulb takes, and will generally overheat and may catastrophically fail. Any catastrophic failures may not necessarily happen quickly. A larger bulb will be underpowered, and will operate at reduced efficiency and may have a shortened lifetime. The ballast may also overheat from prolonged operation with an oversized bulb that fails to warm. Even if the ballast and bulb wattages match, substitutions can be limited by various factors including but not limited to different operating voltages for different bulbs.

Examples are: Pulse-start sodium lamps often have a slightly lower operating voltage than metal halide and mercury lamps of the same wattage, and ballasts for these sodium bulbs provide slightly more current than mercury and metal halide ballasts for the same wattage would. The higher current provided by the pulse-start sodium ballast can overheat mercury and metal halide lamps. Mercury and metal halide lamps may also "cycle" on and off in lower voltage sodium ballasts, such as many 50 to 100 watt ones. Metal halide lamps have an operating voltage close to that of mercury lamps in many wattages, but have stricter tolerances for wattage and current waveform. Metal halides also usually need a higher starting voltage. Most metal halide lamps 100 watts or smaller require a high voltage starting pulse around or even over 1,000 volts. 175 to 400 watt metal halide lamp ballasts can power mercury lamps of the same wattage, but the reverse is not recommended. Mercury lamps 50 to 100 watts will work on metal halide ballasts, but hot re-striking of mercury lamps 100 watts or smaller on metal halide lamps may be hard on the mercury lamp since the starting pulse can force current through cold electrodes and the starting resistor inside the mercury lamp. 1,000 watt mercury lamps come in two operating voltages, one of which is OK for 1,000 watt metal halide ballasts. A few wattages of pulse-start sodium (150 watts?) come in two voltages. A low voltage lamp in a high voltage ballast will be underpowered, resulting in reduced efficiency, possible reduced lamp life, and possible ballast overheating. A high voltage lamp in a low voltage ballast will usually cycle on and off, operate erratically, or possibly overheat. This will usually result in greatly reduced lamp life in any case. One class of sodium lamps is made to work in mercury fixtures, but these only work properly with some mercury ballasts, namely: 'Reactor' (plain inductor) ballasts on 230 to 277 volt lines. 'High leakage reactance autotransformer' ballasts, preferably with an open circuit voltage around 230 to 277 volts. NOT 'lead', 'lead-peak' nor any metal halide ballast! These sodium lamps may suffer poor power regulation and accelerated aging in the wrong mercury ballasts, especially after some normal aging changes their electrical characteristics. Also, these lamps may overheat and will probably have shortened life with pulse-start sodium ballasts. Many sodium lamps require a high voltage starting pulse provided only by ballasts made to power such lamps. To prevent dangerous accidents please keep remote ballasts away from tap points and on an elevated position (approx 5 inches off the floor) using a block or shelf.

H.I.D. light description

High-pressure sodium lamps contain an internal arc tube made of a translucent ceramic material (a form of aluminium oxide known as "polycrystalline alumina"). Glass and quartz cannot be used since they cannot maintain structural strength at the high temperatures (up to 1300 degrees C) encountered here, and hot sodium chemically attacks quartz and glass. Like other HID lamps, the arc tube is enclosed in an outer glass envelope. A small amount of metallic (solid) sodium in addition to mercury is sealed in a xenon gas fill inside the ceramic arc tube. Some versions of this lamp use a neon-argon mixture instead of xenon. Basic operation is otherwise similar to metal halide or mercury lamps. High-pressure sodium lamps produce an orange-white light and have a luminous efficiency much higher than mercury vapour or metal halide lamps.
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Metal halide lamps are constructed along similar lines to mercury vapour lamps. However, in addition to the mercury and argon, various metal halides are included in the gas fill. The most popular combination is sodium iodide and scandium iodide. A few versions of this lamp have lithium iodide as well. A much less common version has sodium iodide, thallium iodide, and indium iodide. The use of these compounds increases the luminous efficiency and results in a more pleasing color balance than the raw arc of the mercury vapour lamp. Thus, no phosphor is needed to produce a color approaching similar to that of a cool white fluorescent lamp with more green and yellow than a mercury vapour lamp (without correction). Some metal halide lamps have a phosphor that adds some orange-ish red light, but not much, since the metal halide arc does not emit much UV.

High-pressure mercury vapour lamps contain an internal arc tube made of quartz enclosed in an outer glass envelope. A small amount of metallic (liquid) mercury is sealed in an argon gas fill inside the quartz tube. After the warm-up period, the arc emits both visible and invisible (UV) light. High-pressure mercury vapour lamps (without color correction) produce a blue-white light directly from their discharge arc. Phosphors similar to those used for fluorescent lamps can be used to give these a color closer to natural light. (Without this color correction, people tend to look like cadavers). Mercury vapour lamps have the longest life of this class of bulbs - 10,000 to 24,000 hours. The technology was first introduced in 1934 and was the first of the commercially viable HID lamps.