LIGHTNING MAKES GLASS

29th Annual Conference of the Glass Art Society, Tampa, Florida, 1999

THE DOMINICK LABINO LECTURE

LIGHTNING MAKES GLASS

Vladimir A. Rakov
University of Florida, Gainesville

1. Introduction
Mother Nature makes glass each time a large amount of energy is released during a sufficient period of time at the Earth's surface, provided that the soil composition is suitable for making glass. The latter condition is satisfied, for example, by sandy soil, with the resultant natural glass being silica glass named "lechatelierite" after the French chemist Henry Le Châtelier (1850-1936). There are two phenomena that are responsible for making natural glass on Earth: meteorites and lightning. Glass that is made as a result of the collision of a meteorite with the Earth's surface is called meteoritic glass or tektite. Glass (a glassy object, to be exact) that is made as a result of a cloud-to-ground lightning discharge is called a fulgurite (from the Latin "fulgur" which means lightning). Fulgurites come in a great variety of forms and can be viewed as nature's own works of art. It is worth noting that lechatelierite (natural silica glass) is not present in obsidian, a glass-like material associated with volcanic activity. On the other hand, volcanic activity is known to generate lightning which, if it strikes sandy soil, may produce a fulgurite. Silica glass has been also made as a result of nuclear explosions. In 1945, the first nuclear bomb (equivalent to 18,000 tons of TNT) was detonated in the New Mexico desert. The explosion formed a crater 800 yards in diameter, glazed with a dull gray-green silica glass. This glass was named "trinitite" after Trinity Site where the first nuclear bomb test was conducted.

2. Characterization of Lightning
On average, about 100 lightning discharges occur every second on the Earth. Only about one-third of them involve ground (others occur in the cloud, between clouds, or between cloud and clear air) and potentially can make fulgurites. The Tampa area in Florida receives more than 12 lightning strikes per square kilometer per year. This is the highest level of lightning activity in the United States.
Each cloud-to-ground lightning involves an energy of roughly 109-1010 Joules. Most of the lightning energy is spent to produce thunder, hot air, light, and radio waves, so that only a small fraction of the total energy is available at the strike point. However, it is well known that this small fraction of the total lightning energy is sufficient to kill people and animals, start fires, and cause considerable mechanical damage to various structures. Lightning is also a major source of electrical disturbances.

The peak temperature of lightning channel is of the order of 30,000° K, which is five times higher than the surface temperature of the Sun (the temperature of the solar interior is 107 K). The lightning peak temperature is considerably higher than silica's melting point which is somewhere between 1600 and 2000° C depending on moisture content, but whether or not silica sand melts and glass is produced depends, besides other, not well-understood factors, on lightning duration. Some lightning strokes last (since a contact with ground is made) for less than a millisecond, others linger for a significant fraction of a second. Lightning current peaks are usually of the order of tens of kiloamperes, but occasionally may exceed 100 kA. The long-lasting current components are typically in the range of tens to hundreds of amperes. The latter are thought to be responsible for making fulgurites.

In the case of natural lightning, it is usually unknown when and where the discharge is going to occur. These uncertainties are largely removed when lightning is artificially initiated (triggered) from an overhead natural thundercloud with the so-called rocket-and-wire technique (for details visit our Web Site: http://www.eel.ufl.edu/~lightning). Some of the most interesting fulgurites have been created in triggered-lightning experiments.

About 30 to 40 lightning discharges are triggered every summer at the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, Florida. The Center is located approximately midway between Jacksonville and Gainesville, Florida, and is a unique facility for studying various aspects of atmospheric electricity, lightning, and lightning protection. The Center is operated by the University of Florida (UF). Examples of still photographs of lightning flashes triggered at Camp Blanding, Florida, are shown in Fig. 1. During summers of 1995 through 1998 over 30 scientists and engineers (excluding UF faculty, students, and staff) from 13 countries representing 4 continents performed experiments at the Center. Many triggered lightning discharges at the Center, that terminated on ground (as opposed to termination on well-grounded objects or systems) created fulgurites.

3. General Information on Fulgurites
The earliest discovery of a fulgurite was reportedly made in 1706 by Pastor David Hermann in Germany. Most people have never seen a fulgurite, and if they have they might not have recognized it for what it was. All fulgurites can be divided in two classes: sand fulgurites and rock fulgurites. Sand fulgurites are usually hollow, glass-lined tubes with sand adhering to the outside. Rock fulgurites are formed when lightning strikes the bare surface of rocks. This type of fulgurite appears as thin glassy crust with which may be associated short tubes or perforations lined with glass in the rock. Glass of this type may be relatively low in silica and exhibit a wide variety of colors, depending on the composition of the host rock. Rock fulgurites are found on the peaks of mountains.

When lightning strikes sandy soil, the air and moisture present in soil are rapidly heated, and the resultant explosion-like expansion forms the central tubular void. As stated before, quartz sand melts at a temperature of about 1600-2000° C depending on moisture content, and molten glass is pushed to the periphery of the void. Subsequent relatively rapid cooling causes the glass to solidify. A general condition for sand fulgurite formation appears to be the presence of a relatively dry dielectric such as quartz sand overlying a more conducting soil layer or the ground water table, with the depth of the latter probably determining the limit for vertical extent of the fulgurite formation. The diameter of fulgurites ranges from a quarter of an inch to 3 inches, and the color varies, depending upon the type of sand from which they were formed. Sand fulgurites are usually tan, grayish, or black, but almost translucent, white fulgurites have been found in Florida pan-handle beaches. The inner surface is glassy and exhibits numerous bubbles. The walls are usually about 0.5-2 mm thick, but may be paper thin. There appears to be no relation between tube diameter and wall thickness. Sand fulgurites are quite fragile and very difficult to excavate in one piece. An example of sand fulgurite is shown in Fig. 2.

Since fulgurites are real glasses, they are very resistant to weathering and are usually well preserved for a long period of time. For this reason they are used as paleoenvironmental indicators. For example, many fulgurites are found in the Sahara desert, where presently there is little lightning activity, confirming that very different conditions existed in this region in prehistoric times. A fossil fulgurite thought to be 250 million years old has been reported.
Fulgurites have been also produced artificially passing laboratory arc current through sand. It has been found by researchers at the Technical University of Ilmenau, Germany, that currents higher than 50 kA lasting for some hundreds of microseconds, typical of impulsive components of the lightning current are incapable of making a fulgurite (only some very thin fragments). On the other hand, relatively low magnitude currents of some hundreds of amperes lasting for some hundreds of milliseconds yielded well-formed fulgurites with diameters of 7 to 15 mm. It has been also observed that the higher the current the larger the cross-sectional dimensions of fulgurite. Different forms of fulgurites were obtained in dry and wet sand. Fulgurites in wet sand were more curved and had more irregular outer surface. The latter feature was attributed to the pressure of vaporized moisture that squashed the fulgurite when the arc pressure in the central tubular void disappeared, while the glass was still plastic.

4. Fulgurites Created at the ICLRT at Camp Blanding, Florida
4.1. Underground Power Cable Project (1993-1994)
In 1993, an experiment, sponsored by Electric Power Research Institute (EPRI), was conducted by Power Technologies, Inc. to study the effects of lightning on underground power cables. In this experiment three 15 kV coaxial cables with polyethylene insulation between the center conductor and the outer concentric shield (neutral) were buried 5 m apart at a depth of 1 m, and lightning current was injected into the ground at different positions with respect to these cables. One of the cables (Cable A) had an insulting jacket and was placed in PVC conduit, another one (Cable B) had an insulating jacket and was directly buried, and the third one (Cable C) had no jacket and was directly buried. About 20 lightning flashes were triggered directly above the cables which were unenergized.

The underground power cables were excavated by the University of Florida in 1994. The damage found ranged from minor punctures of the cable jacket to extensive puncturing of the jacket and melting of nearly all the concentric neutral strands near the lightning attachment point. Some damage to the cable insulation was also observed. In the case of the PVC conduit cable installation, the side wall of the conduit was melted, distorted and blown open, and the lightning channel had attached to the cable inside and damaged its insulation. Photographs of the damaged parts of the cables are shown in Fig. 3.

Five fulgurites were found during the excavation of the underground cables. The excavation process was a slow, methodical one and covered an area with dimensions of 4 m x 20 m. Various techniques developed in paleontology were used to remove the fulgurites. The fulgurite excavated over Cable B was nearly vertical with a length approximately 1 m and an average diameter of 1.5 cm at the top and about 0.4 cm at the cable. This fulgurite was the most complete fulgurite excavated as part of the underground power cable project. It was unearthed in one piece with very little reconstruction necessary. This fulgurite is presently on exhibit at the Electric Power Research Institute (EPRI) in Palo Alto, California.

4.2. World-Record Fulgurite (1996)
After the excavation of fulgurites produced as part of the underground power cable project we started checking for fulgurites at all known lightning strike points at the Camp Blanding facility. Each year we trigger on average 30 to 40 discharges some of which strike ground as opposed to terminating on the rocket launcher. Additionally, the facility receives about 5 lightning strikes that occur naturally, irrespective of our lightning triggering activity. Our surveillance cameras and observer reports allow us in many cases to find the strike point on the ground. Such strike points usually appear as holes in the ground with the surrounding grass being killed (as becomes apparent within a few days). When the strike point on the ground is found and flagged, it is impossible to predict if a fulgurite has been created, and, if so, what its shape and dimensions are. One such find in 1996 led to many days of careful digging and resulted in the unearthing of a fulgurite having two mostly vertical branches, one about 16 feet and the other about 17 feet long. It was recognized by the Guinness Book of Records as the world's longest excavated fulgurite. The 17-foot branch of the world-record fulgurite is shown in Fig. 4. The successful excavation would not be possible without special tools and the paleontological skills of Mr. Dan Cordier and Mr. Mike Stapleton. The world-record fulgurite was carefully separated into sections and covered in plastic material used in paleontological digs. Each section was measured with special instruments and labeled for subsequent reassembling. At this time, the world's longest fulgurite is looking for a home - a museum with sufficient space to display this magnificent subterranean creation of atmospheric electricity. We have dug up about ten other fulgurites at Camp Blanding that are on average 4-5 feet long.

4.3. Artistic Installation "Petrified Lightning from Camp Blanding" (1997-1998)
In the summer of 1997, researchers at the International Center for Lightning Research and Testing, Dr. M. A. Uman, Mr. D. J. Cordier, Mr. K. J. Rambo, and Mr. M. V. Stapleton, worked with Mr. Allan McCollum, an internationally recognized artist, to create the fulgurite that became the centerpiece of an artistic installation entitled "Petrified Lightning from Camp Blanding". The installation was on display at the USF Contemporary Art Museum in Tampa in Fall 1998 and was accompanied by a simultaneous exhibit and presentation on the project at the Tampa Museum of Science and Industry (MOSI). The project was curated and organized by Margaret A. Miller, Director of the USF Contemporary Art Museum, Jade Dellinger, Independent Curator, and Wit Ostrenko, Executive Director of MOSI.

The Camp Blanding (fulgurite production) stage of the project involved the experimentation with minerals of which the fulgurite was to be made and with various types of containers that were used to avoid the very difficult excavation process. A fulgurite made of staurolite (75%), ilmenite (15%), and rutile (10%) is shown, as an example, in Fig. 5. Allan McCollum selected zircon (ZrSiO4), a heavy mineral that is mined by Du Pont not far from Camp Blanding, and that is primarily used in the refractory industry. Zircon melts at 2100-2300° C a melting temperature which is slightly higher than for silica. Zircon sand was packed in a 4-foot section of a PVC pipe 6 inches in diameter equipped with two axial metallic electrodes forming a gap of 15 cm or so in the sand. This container was placed in a red trash receptacle located near the base of a rocket launcher used to trigger lightning. Allan McCollum, the artist, helped with the design of the experiment and was the one to push the rocket-launch button. When lightning was initiated, lightning current passing through the gap produced a zircon sand fulgurite resembling a bone. A Florida souvenir factory, Sand Creations, produced 10,000 replicas of the fulgurite. The replicas were made from a mixture of zircon (the same mineral from which the original was made) and epoxy. The artistic installation is shown in Fig. 6. As another element of the installation Allan McCollum prepared a series of booklets containing more than 50 texts on fulgurites, lightning and related subjects. The booklets were presented on tables in a room adjacent to the display of 10,000 replicas of the fulgurite.

Figure Captions
Fig. 1. Photographs of lightning flashes triggered in 1997 at Camp Blanding, Florida. Top - a distant view of a strike to the test runway; bottom - a close-up view of a strike to the test power system.
Fig. 2. A sand fulgurite made by triggered lightning in 1993 at Camp Blanding, Florida.
Fig. 3. Lightning damage to underground power cables. (a) Cable A, (b) Cable B, (c) Cable C. Note fulgurites in Figs. 3a and 3b. See text for details.
Fig. 4. World's longest (17 feet) excavated fulgurite, made in 1996 at Camp Blanding, Florida.
Fig. 5. A fulgurite made of staurolite (75%), ilmenite (15%), and rutile (10%) at Camp Blanding Florida.
Fig. 6. Artistic installation "Petrified Lightning from Camp Blanding" by Allan McCollum displayed at the USF Contemporary Art Museum, Tampa, 1998.

Film & Video Lighting for low-budgets

OK so after making sure that your actor is saying the right lines, that the picture is in focus and the camera is recording probably the last thing on your mind is the way the picture is lit. But wait, the difference between something that is well lit and something that isn't can be the difference between a film that's great and one that's totally pants.
Generally you want to keep your light level up. Video cameras work best in a certain range - too bright and whites get blasted out (use a Neutral Density Filter to combat this effect) too dark and you get a grainy image without much colour. Well lit footage makes your film look like it was shot with a really good camera.
But you also want to create a play or light and shade on the objects before you, revealing depth, form and mood.
So how do we do light a scene?
I was working with a group making a film (I was making the tea this time around) who were shooting on film. They had some proper lights, so I had the opportunity to observe how these semi-pro's went around their work. After sitting around for 40 minutes waiting them to set up I figured out their technique. They blasted a light at the actors which gave hideous shadows so they blasted another light to get rid of the shadows, which created another shadow etc. etc. etc. All this only served to slow everything down to a painfully slow pace and tire everyone out.
My advice, keep it simple and fast. Work with the light that is already there.
Put as many existing lights and lamps on in the room to increase the room's overall light level. (Techie Tip! Lights that are in the scene anyway are called 'practicals')
Replace existing lightbulbs with more powerful lightbulbs.
Use a reflector to bounce an existing light source onto your subject.
Reflectors
A reflector is a piece of silvery, gold or white fabric stretched over a frame. Lastolite make some really cool ones that explode open into massive circles. They come in two main varieties : silver/white and gold/white (the gold is good for warming up flesh tones). They are always a good investment, but if you can't afford them there's a cheaper solution around the corner.
Reflectors for nowt
Nip down to the supermarket and get hold of some really big cardboard boxes and some aluminium foil. Cut the boxes into massive sheets taking advantage of its folds, and stick the foil to the boards to create folding reflectors. Use the shiny side of the foil for a hard reflector or the dull side for a more diffuse reflector. You could also try looking for reflecting sun shades (y'know the ones people put in their car windows on hot sunny days).
Getting more complicated now...
On board camera lights.
Waste of time. They sit on your camera, zapping power, and have all the strength of a decrepid glowworm. They also blast straight ahead, which flattens rather than flatters your subject and create bloody big shadows over the rest of your picture. Forget 'em.
Now for the big boys (and girls). Proper big lights like the pros use. Remember our budget (or lack of budget)here so don't buy 'em, rent 'em.
Big Lights
To get more bang for your buck, or strictly more wattage from your wallet get a bigger light. There are a few lights that can be carried by a separate person (such as the Reportalight) but to seriously light a scene you need lights over 100 watts. These lights come with stands which you can adjust to the appropriate height, they also have filters and barndoors so you can adjust the quality and quantity of light they put out. The most standard pro light is a Redhead. Now I thought they were called Redheads cos the back of them are red (well, a deep orange really), but apparently its because the more powerful ones are called Brunettes and the most powerful are called Blondes (well, they do say that blondes have all the fun).
There's a couple of things to watch out for when you are using these. Be very careful when adjusting the barn doors as they tend to get quite hot (here speaks a man who saw the skin off his fingertips vaporize before his eyes). Oh, and make sure that the stands are secure and that nobody can accidentally knock them over, as a hot moving object crashing down on cast and crew is a bad idea.
If you're shooting in a small room keep the lights switched off when you're not using them as the room can get very hot very quickly. (We were making a documentary and had lit a wall with a blonde cos that was all they had left at the renting place. That room go soo hot, it was freezing outside and we were all in this room sweating buckets).
Very Big Lights
During December I came home from shopping one night, turned the corner and there was this massive blinding white light right outside my house. It was shining through the trees and kinda looked like something out of the X-Files, what with it being up in the trees. Turns out that they were shooting an advert there, dunno what for, but when I got home my shoes were covered in false snow (which according to the news is the same snow they used in GoldenEye). Wow! I trod in James Bond snow!

Three light setups
So let's assume you have blagged a set of three redheads from a local hire place. What next?
Set something up you want to light. The example that is always used is a person. Set up your first redhead (they come with little tripods which they attach to) and put it in front of the subject at a 45o angle looking down on them a little. This is the key light. Our subject is now lit. Hurrah!
But the subject does seem to have heavy shadows on the opposite side of their face. Erect another redhead making this one more diffuse by reflecting it off a wall, a reflector or by putting a scrim (basically a grille) in front of it. This is the fill light and helps soften the shadows.
You can also add a light above and behind the subject to add a slight corona (ie. white line) around them that helps to separate them from the background. This is called the back light.
Remember that the further you move a light away from the object you are lighting the less light falls on it - not exactly rocket scinece eh? Well think back to your Physics lessons and you might also be able to remember the inverse square law. This states that 'the intensity of light observed from a source of constant intrinsic luminosity falls of as the square of the distance from the object'.
Wow! But what does that mean? Well if I am lighting Cameron Diaz if I double the distance she is from the light (by moving the light to the other side of the room) I would decrease the brightness of the light so it was only a quarter of what it was, resulting in a very dark Miss Diaz so that nobody good see her. Not good.

Avoid Backlighting - This is where your subject is standing with the sky or a window or white wall behind them. The camera goes 'Hey, loads of white I better set my exposure to that', so when you come to look at your footage all you can see it a silhouette of your subject and you can hardly see their face. Solution - turn around, and use the light from the wall/window to light your subject (Some cameras might have a BLC - Backlight Compensation button, but these tend to on the whole suck).

All white light is not white, right?
Light not only differs in intensity, but also in its colour. Lights have different colour temperatures. Sunlight is kindof bluey, artificial light (like lightbulbs and stuff) is orangey and fluorescent strip lights are greeny.
Sunlight
Bluey
Artificial Light
Orangey
Fluorescents
Greeny
Your eyes can sort this information out, but the camera tends to make everything look all one colour if its on the wrong setting. So remember to check the white balance on your camcorder.
White balance is essentially what colour your camera thinks is white. Some cameras have buttons for this i.e. indoors, outdoors etc. Other cameras sort this out automatically (although they can make a botch job of it) and some allow you to set it manually (by sticking a piece of white card in front of it and saying 'Hey, this is white you dumb camera').
If at all possible use a colour monitor (ie. play around when your camera is plugged into the telly) to see what colour different lights look on through your camera and how effective your camera's auto white balance settings are.
Try changing your camera's white balance for effect. Try using your indoor setting when filming sunsets etc.to make it even redder, and try using your outdoor setting indoors to create a blue clinical feel.
Gels
When you add light to a scene you usually end up mixing light of different colour tempertures. To make light all of the same colour you have to fit gels over the lights. Gels are plastic strips that attach via bulldog style clips to the light's barndoors. Most of the time you will simply add a blue gel to a Redhead to give it daylight balanced light.
You can double up gels or use theatrical gels to create really strong lighting schemes (see Dick Tracy). We tried this out on one film, starting off with the Redhead bare, and increasing the number of orange gels, so that by the end of the film the light is almost red, turning a normal bedroom into a vision of hell.

Light at Night
Lighting at night is no fun at all. However much light you seem to pour onto a subject it still looks dark and grainy, either that or your subject looks blasted out - white and washed out, like a rabbit caught in a car's headlights.
The best bet is to shoot all your night stuff just before light is about to go, when it looks like night but there is still some light on the horizon (you better be quick), or shoot it day for night.
Day for night is a cheapo 60's style technique. Check out ITV series from that period and Connery Bond films. You fit a blue filter to the front of the camera and decrease the exposure. Remember to make sure that what is in front of the camera looks right, so lights in houses need to be on and remember, no birds flying through shot!
Lighting inside cars
Have you ever really paid attention to scenes where there are two characters driving along at night talking to each other. The car's interior is lit so that both actors look like they are sitting there with 1000W lights sitting on their laps (which they probably are). Compare this to real life - light in car? nil.
We shot a scene like this using a portable light aimed downwards bounced off a reflector that was sitting in the back seat. Unortunately this car was a mini so there wasn't much room and we had rented the world's largest reflector which proceeded to unfold itself halfway through the shot appearing in the back seat like a surprised passenger! Take two.
Burn Baby Burn - creating fire light.
Need to create a decent fire effect on the faces of two characters as they watch a building burn? Aim a redhead with an orange gel away from the actors towards a massive reflector. Shake the reflector, aiming the light onto the actors. Add burning sound effects and voila 'instant fire'.
TVee nights - creating TV and monitor light.
A similar method can be employed to light a room of people watching television at night. Blast a blue light over at your actors and wave a piece of paper in front of it very fast to create a flickering effect.
Visible Light Beams
If you want to be a real show off and start painting with light you might want to consider using a smoke machine. By diffusing the smoke so that a thin haze fills the room you can shine light through it so that the beam reflects off the smoke particles and can be seen. Watch any episode of My So Called Life or Party of Five for a brief example. Smoke machines use a liquid which it heats up producing clouds on non-toxic smoke - you can usually rent one for ten or twenty quid a day.

'Turn off the light on your way out'
Good lighting adds so much to your film. It's like having another actor. Use light to create a mood, to tell us more about the characters and the world they live in.
The greatest thing about making movies is that it is pure madness. All you are doing is trying to capture rays of light onto a thin piece of celluloid or videotape. Moviemaking is simply painting with light.

ceiling lighting - Cavalcade 20-Light Chandelier

Features and Benefits
Accommodates sloped ceilings
UL and CUL listed
Quality control guarantee that only the finest materials are used and design integrity is maintained
(1) light ceiling fixture
Specifications
Size Dimensions: Fixture is 32"W, Canopy is 6.5"W, Downrod telescopes from 12" to 24"
Warranty: Manufacturer provides item warranty against material defects and workmanship
Bulbs Included: Yes
Enlightened Benefit: Metal used features recycled content and is itself recyclable. This product harnesses Low Voltage power which can produce 21/2 time more light than a line-voltage incandescent lamp - saving you energy.
Finish: Nickel
Quantity/type Of Bulbs Needed: (20) 10 Watt Bulbs
Recommended Wattage Of Bulbs: 10 Watt Max

How Light Works

What is Light?

Why is it that a beam of light radiates outward, as Young proved? What is really going on? To understand light waves, it helps to start by discussing a more familiar kind of wave -- the one we see in the water. One key point to keep in mind about the water wave is that it is not made up of water: The wave is made up of energy traveling through the water. If a wave moves across a pool from left to right, this does not mean that the water on the left side of the pool is moving to the right side of the pool. The water has actually stayed about where it was. It is the wave that has moved. When you move your hand through a filled bathtub, you make a wave, because you are putting your energy into the water. The energy travels through the water in the form of the wave.

All waves are traveling energy, and they are usually moving through some medium, such as water. You can see a diagram of a water wave in Figure 1. A water wave consists of water molecules that vibrate up and down at right angles to the direction of motion of the wave. This type of wave is called a transverse wave.

Light waves are a little more complicated, and they do not need a medium to travel through. They can travel through a vacuum. A light wave consists of energy in the form of electric and magnetic fields. The fields vibrate at right angles to the direction of movement of the wave, and at right angles to each other. Because light has both electric and magnetic fields, it is also referred to as electromagnetic radiation.

Light waves come in many sizes. The size of a wave is measured as its wavelength, which is the distance between any two corresponding points on successive waves, usually peak-to-peak or trough-to-trough (Figure 1). The wavelengths of the light we can see range from 400 to 700 billionths of a meter. But the full range of wavelengths included in the definition of electromagnetic radiation extends from one billionth of a meter, as in gamma rays, to centimeters and meters, as in radio waves. Light is one small part of the spectrum.

Lighting

Not to be confused with lightning.

Low-intensity lighting and haze in a concert hall allows laser effects to be visible
Lighting includes both artificial light sources such as lamps and natural illumination of interiors from daylight. Daylighting (through windows, skylights, etc.) is often used as the main source of light during daytime in buildings given its low cost. Lighting represents a major component of energy consumption, accounting for a significant part of all energy consumed worldwide. Artificial lighting is most commonly provided today by electric lights, but gas lighting, candles, or oil lamps were used in the past, and still are used in certain situations. Proper lighting can enhance task performance or aesthetics, while there can be energy wastage and adverse health effects of lighting. Indoor lighting is a form of fixture or furnishing, and a key part of interior design. Lighting can also be an intrinsic component of landscaping.

common traditional track lighting components

Track

Track lighting track is commonly available in black or white and typically ships in 2, 4, 6 and 8 foot segments. These segments may be cut in the field if they are too long or joined together with connectors to form longer track runs. Most track today conforms with one of three standards (‘H’, ‘J’ or ‘L’ type). Although the standards are externally similar, each is formed differently inside and will only work with fixtures designed for that specific standard. If you are installing a new system, you should typically use H-type track. If you are adding fixtures to an existing system, it’s important to ensure that you have properly identified your existing track standard before purchasing fixtures or other components. Track is available in single and dual circuit versions. Dual circuit track is slightly more complicated than the more common single circuit version and is not automatically configurable using our wizard. If you have questions about dual circuit track, please call our design assistance line.

Track Connectors

Track runs longer than eight feet will require one or more ‘inline connectors’ between track segments. These will be included automatically when using our ‘build your own track system wizard’, otherwise they should be added manually. Track systems that must turn for any reason should be configured with ‘L’, ‘T’ or even ‘X’ connectors accordingly.

Line voltage Track Heads

‘Track heads’ are the common spotlight fixtures designed to be attached directly to the track to cast light in any direction. Track heads that use standard, 120 volt bulbs are referred to as ‘line voltage track heads’. Although these fixtures are often quite large, they produce ample light and are very affordable.

Low Voltage Track Heads

Low voltage track heads are rapidly growing in popularity. These heads include an integrated transformer that converts power to a level that allows the use of smaller low-voltage halogen lamps. This results in much smaller fixtures that unobtrusively produce precision accent lighting. Low voltage track heads also consume less power than larger line-voltage styles.

Pendants

Fixtures that hang below the track lighting system on a flexible cable are called pendants. Pendants are used to provide both light and color accents. Although pendants are often installed individually without using a track system (see monopoint lighting) they may also be easily snapped in to a new or existing track system.

Suspension Standoffs

Most track systems are attached directly to the ceiling. In spaces with very high ceilings or exposed ductwork, it may be desirable to suspend the track system below the mounting surface. All track systems may be configured with standoffs of various lengths that will accomplish this quickly and cleanly.

Suspension

Stems Although less common than suspension standoffs, track lighting fixture heights may also be adjusted using suspension stems. Stems and standoffs are different in that standoffs attach between the track and the ceiling to suspend the entire track while stems attach between the track and the fixture to suspend an individual fixture below the track.

Powerfeeds

All track lighting systems must draw power from somewhere. The component that attaches to both the track system and the power outlet or junction box in a room is called the powerfeed. ‘Live end connectors’ are small components that attach to the end of a track run while the more versatile ‘floating canopy connectors’ may be attached anywhere along the track lighting system. Some special installations (often when suspending a track system below an exposed ceiling) will use a ‘BX connector’ that will allow an electrician to power the track system from exposed, shielded conduit wiring (commonly referred to as Romex.)