Purdue Extension 4H Lighting the Way. Division IV Electric Project

Transcription

1 Purdue Extension 4H-1000 Lighting the Way Division IV Electric Project 1

2 Lighting the Way Welcome to Division IV of the 4-H Electric Project by Roger Tormoehlen, Professor and Head, Department of Youth Development and Agricultural Education, in cooperation with the Indiana State 4-H Electric Committee. What You Will Learn 1. Why light is important to us. 2. The difference between direct and reflected glare. 3. How light contrast affects our ability to see and work. 4. The effect that shadows have on your ability to see. 5. How the color of the walls, ceilings, and floor in a room affect your ability to see. 6. The difference between general and task lighting and when to use each. 7. How to make a house lamp. What You Will Do 1. Join and attend the meetings of your local 4-H club. 2. Attend the 4-H electric meeting(s) of your county. 3. Read this manual. 4. Complete the activities presented in this manual. 5. Complete the record sheet in the back of this manual and submit it as instructed. (You should submit the record sheet to your 4-H electric leader when completed for his/her signature). What You Will Exhibit Exhibit one of the following: 1. Made or remade household lamp. 2. Poster on any topic covered in this manual. 2

3 Contents Section page # Welcome...2 Let s Look at Light...4 Quantity of Light...4 Light Quality...4 Preventing Direct Glare....5 Contrasts....6 Shadows...7 Surface Color...7 Methods of Lighting Lightbulb Language...10 Lightbulb Types Color Temperature...11 Recycling Compact Fluorescent Bulbs What s a Watt? Exhibits Indiana 4-H Club Record H Electric Lamp Check Sheet H Electric Poster Check Sheet

4 Lighting the Way Let s Look at Light Picture this. You are outside on a bright, sunny day and have to go into a darkened shed for a tool. Can you see what you are doing? The answer is probably no, because there is no light and without light you cannot see. But after awhile, your eyes begin to adjust and even though there is not much light available, your eyes strain until you begin to see a bit. The picture is not clear or sharp, because there is not enough of nature s light available to aid your eyes. To illustrate this to yourself, find a darkened closet or room in your home, go into it, and close the door, being careful not to lock yourself in. Can you see? If no, why not? After a while, do your eyes begin to adjust? Can you see clearly? Now turn on the light. How easily can you see now? Are lights inside important to you? Why? Good lighting is important to us for many reasons, even though we can see in poor lighting. Poor or inadequate lighting often results in poor work and may be the cause of accidents. Quantity of Light Have you ever tried to read a book or magazine and found it difficult to see the words? If you have, then maybe the problem was lack of light. Not enough light can result in eye fatigue, because our eyes must work harder for us to see. The standard measurement for light quantity is the foot-candle. A foot-candle is the amount of light from a standard candle falling on a square foot of surface at a distance of one foot. You can get an idea of what a foot-candle is by setting a burning candle one foot from a 12 by 12 piece of white paper and turning out all the lights (Figure 1). Another term used to describe the quantity of light is lumens. One lumen is equal to one foot-candle falling on one square foot of area. Today the amount of light given off by a light bulb is measured in lumens How do you know if there is enough light for the job you wish to do? The quantity of light can be measured by using an instrument called a light meter. A light meter is a hand-held device that measures the amount (intensity) of light in foot-candles. Light Quality 1 Foot Figure 1. One foot-candle Have you ever been watching television when the sun shines through a window onto the television screen, making it difficult or impossible to see the screen? Why is this? 4

5 Did anyone ever shine a flashlight directly into your eyes? Did you have trouble seeing for a few moments afterward? Why is this? The sunlight shining onto the television screen and the light from the flashlight in your face both caused glare. Not only does glare make it difficult to see, as it did in the two cases above, but it also could make your eyes very tired. There are two types of glare, direct and reflected. Direct glare is bare, unshielded, or dazzling bright light that is annoying. Which of the examples above (flashlight shining in eyes or sun shining on television screen) is direct glare? If you selected the flashlight example, congratulations, you are right! Can you list some more examples of direct glare? Reflected glare occurs when light is bounced off a shiny, bright surface, such as pages of paper, desk tops, shiny painted surfaces, television screens, and other similar objects. In the television example above, the bright sunlight was reflected off the television s shiny screen into the viewer s eyes. Preventing Direct Glare 1. Direct glare Direct glare can be caused by light from a lamp with no shade. How can we eliminate the direct glare? If you said to shade the light bulb (add a lampshade), good idea. Reflected glare 2. Reflected glare can be eliminated or greatly reduced by changing the position of the light source or work area. In the TV example above, how could you eliminate the reflected glare? If you said that you could move the TV so that the sun s light would no longer hit the TV, great. If you did not want to move the TV, you could close the window shade, preventing the sunlight from shining on the TV. 5

6 Can you read this Lighting the Way Activity One Demonstrate glare for yourself (Figure 2). Materials needed Piece of cardboard Scissors Ball-point pen Unshaded lamp Directions Figure 2. Demonstrating glare 1. Cut a 2-inch hole in the middle of the cardboard. 2. Around the hole, write the words Can you read this? 3. Before turning on the lamp, hold the cardboard in front of and just above the lamp s bulb. 4. Turn the lamp on. Now can you read the words? 5. If you couldn t read the words, why? Contrast Take a minute to look at Figure 3. The sharp differences between the black and white, or the contrast, make the message hard to read. Many rooms are poorly lit. This is usually caused when there is only one light source in a room. This causes part of the room to be lighter and the other to be darker. This contrast is tiring to the eyes, because they are constantly trying to adjust to the differing amounts of light. Activity Two Figure 3. Contrast Determine light contrast in a room. Materials needed Flashlight Directions 1. Take a flashlight into a darkened room. 2. Hold the flashlight at waist level, pointed toward the ceiling. 3. Stand in one corner of the room and turn on the flashlight. How well is the room lighted? Are there any contrasts formed by the light? 4. Now move to the center of the room with the light on. Is the room lighted differently? 5. How is the light contrast now? 6

7 Shadows Light is needed to see. But there are times when, even with sufficient light, we still are unable to see properly. Why? Shadows. Shadows are created when light is blocked by an object, producing a dark, shaded area in place of the light. Shadows make it difficult to see because they decrease the amount of light falling on the work area and create sharp contrasts. It is virtually impossible to eliminate shadows, but good lighting creates shadows where they do not cause problems. Some ways to prevent or minimize shadows are: Use ceiling lighting if possible. Ceiling light is less likely to be blocked by objects in the room and, thus, less likely to cause shadows. Place lamps such that shadows do not fall in the work area. When reading, writing, or working on a job be sure the light comes from the side opposite the hand being used. (Self test: If you are right-handed and writing a letter, on which side of the notepad should the lamp be placed? You are correct if you said the left side.) Activity Three Determine the best lamp location to avoid shadows. Materials needed Lamp Book Pencil 4-H Electric manual Directions NOTE: This activity should be performed after dark, when there is no light from the sun shining into the room Place the lamp and book on the desk. Seat yourself at the desk. Place the lamp at various locations around the book above book, left of book, right of book, etc. Attempt to read a paragraph with the lamp at each location. Which location produced the least shadowing and thus, for you, is the best reading location? Surface Color All the light in a room does not have to come directly from a particular light source. Some of it comes indirectly, after it has been reflected or bounced off surfaces in a room. These surfaces can include the ceiling, walls, floors, or other objects found in a room. Therefore, direct lighting comes directly from the light source to an object, whereas indirect lighting comes from a light source and is reflected from a surface that disperses the light to an object. 7

8 Lighting the Way This illustrates that it is not only the number of lights or their placement in a room that is important, but also how well the surfaces reflect light. The color of surfaces in a room affects how well they reflect light. Lighter colors reflect light (up to 90 percent of the available light) and therefore give more light than darker colors, which reflect as little as 20 percent of the available light. Ceilings are often colored lighter than floors. They, therefore, reflect more light down into the room. This is ideal, since it is less likely to cause the glare and shadows discussed earlier. Activity Four Determine the sources of light. Materials needed Pencil 4-H Electric manual Directions 1. Select a room in your house. 2. Answer the following questions. A. B. C. D. E. F. G. H. I. What is the name of the room you selected? How many light sources are there? (Don t forget windows!) What are the light sources? What color is the ceiling? What color are the walls? What color is the floor? Is part of the light in the room coming from indirect sources? What surfaces are reflecting the light? Are the reflecting surfaces dark or light colored? 8

9 Methods of Lighting There are two basic types of lighting in a room. These are general and task lighting. General lighting is designed to light up a large area such as a room. Ceiling lights are an example of general lighting. Task lighting is designed to light up a specific or smaller area such as a desk. Lamps are an example of task lighting. Activity Five Identify general and task lighting. Materials needed 4-H Electric manual Pencil Directions In each room of your home, identify the light sources as either general or task lighting. For all lighting situations list the type of bulb used. Type of Lighting Room General/Task Lighting Type of Bulb Incandescent/Flourescent/LED Bathroom Bedroom(s) Kitchen Family Room Other 9

10 Lighting the Way Lightbulb Language Watts is the amount of electricity used by a bulb and lumens is the amount of light produced by a lightbulb. The higher the lumens rating of a bulb, the brighter the light will be. The two basic categories of bulb life (Figure 4) (average number of hours a bulb produces light) are: Figure 4. Standard and longer-life bulbs 100 Watts 1470 Lumens Longer life Avg. Life Watts 1750 Lumens Standard life Avg. Life 750 The average life is usually listed on the lightbulb package. In general, the lower the number of lumens, the longer the bulb should last. Standard bulbs tend to have more lumens. Therefore, they are brighter, but tend not to last as long. Lightbulb Types Lightbulbs produce light. They come in a variety of sizes and types. The most common types of lightbulbs are incandescent, fluorescent, and light emitting diode (LED). Glass bulb Filament 10 Incandescent bulbs (Figure 5) produce light by heating the filament. To give the white light that our bulbs do, the filament must be very, very hot and it is necessary that the filament be in a vacuum (free of oxygen) or it will burn up quickly. In modern bulbs, the filaments are surrounded by gases which do not burn, such as argon or nitrogen. Fluorescent bulbs Compact fluorescent bulbs are commonly available in the twist design and in tubes (Figure 6). Fluorescent lights are becoming increasingly popular, because they produce a light more like daylight, they last longer, and they produce an equal number of lumens at a lower wattage than incandescent bulbs. Lead-in Bulb filled with argon and nitrogen gases Base Glass support rod Glass seal Cement Wire support Insulation Figure 5. Parts of an incandescent bulb

11 The fluorescent light has two small filaments and a small amount of mercury in the tube. The filaments heat up first and vaporize the mercury. The electric current then arcs from one filament to the other through the mercury gas. This current produces an invisible type of light called ultraviolet light. A special kind of powder in the tube changes ultraviolet light into visible light. Tube design The filament emits electrons which strike mercury atoms producing ultraviolet rays which hit phosphor powder inside producing visible light. Figure 6. Flourescent bulbs Twist design Light Emitting Diode (LED) LED lights are also becoming popular because of their low energy consumption, long life, and brightness. An LED produces light when an electric current passes from one crystal to another. There is no gas to heat to produce the light, so there is no energy wasted in producing heat. Popular uses for LEDs are in flashlights and light strings for decoration. They are also used in many other applications, including in electronic devices, traffic lights, and automobile lighting. In 2008 LEDs became available for household lighting (Figure 7). The light used in your Division 2 shake-light project is an LED. Figure 7. Light-emitting diode Color Temperature The overall color appearance of the light that comes from a light source is called color temperature. This is measured in degrees Kelvin, or K. Color temperature creates the mood or ambience of the space you are lighting and can influence shopping behavior or work performance. Think of it as heating a piece of iron in a fire. At first the iron becomes red-hot, and will be reddish-yellow in color. This is a warm color and corresponds to an incandescent lighting temperature of about 2700K. Warm lighting can usually be seen in restaurants, hotels, small shops, and homes. As you continue to heat the iron, it becomes white-hot, and will be white in color. This corresponds with a lighting temperature of about 4100K, which is a cool-white light. Applications of this lighting temperature include office areas, classrooms, hospitals, and conference rooms. 11

12 Lighting the Way Further heating of the iron causes it to become blue-hot, or blue in appearance, similar to flash-bulbs and stars. The lighting temperature is approximately 5000K and is most often used in galleries and museums, medical exam areas and printing companies. Recycling Compact Fluorescent Bulbs Compact Fluorescent Bulbs (CFL) contain mercury. Because mercury is a hazardous material which can be harmful to human health, compact fluorescent bulbs must be recycled. Some cities and counties offer recycling programs for CFLs. Also, check with your local hardware store, as many of the major hardware chains will recycle CFLs. What s a Watt? The amount of electric energy used or produced is measured in a unit called a watt. Lightbulbs are rated by wattage, or the number of watts they use during one hour of operation. Incandescent bulbs consume more energy than comparable fluorescent lights. For example, an average 60-watt incandescent bulb produces about 600 lumens of light, while a 14-watt compact fluorescent bulb produces about 900 lumens of light and uses considerably less energy. Here are some other examples of comparable wattages. Incandescent Fluorescent 60 watts 14 watts 75 watts 20 watts 100 watts 23 watts watt 3-way watt 3-way Activity Six Determining the types and wattages of light bulbs. Materials needed 4-H Electric manual Pencil Directions For every bulb that you can find around you home, record the bulb type and wattage on the chart on next page Digging Deeper 12 Using the wattage list on this page, figure how much you can save by changing the incandescent bulbs in your home to compact fluorescent bulbs.

13 Electric utilities measure the amount of energy to bill to a customer in kilowatt-hours. To figure the number of kilowatt hours you can save in one hour, use the following formula: Kwh = Watts x 1 hour 1000 This same formula can be used to calculate the energy usage of any appliance or equipment in your home. Remember, it s watts times hours, divided by 1,000, to equal kilowatt hours. EXAMPLE: Let s calculate the energy to light a bedroom for an evening (5 hours). This bedroom has one desk lamp with a 75-watt equivalent compact fluorescent bulb that uses 20 watts per hour, and an overhead light with three 60- watt incandescent bulbs. Step #1: Add the total watts used per hour = 200 watts per hour Step #2: Fill data into the formula Kwh = Watts x hours 1000 Kwh = 200 watts x 5 hours 1000 Kwh = 1000 watt hours 1000 Kwh = 1 If the cost of electricity is 6 cents ($0.06) per Kwh, then the cost of lighting the room for 5 hours would be: Energy used (Kwh) x cost per hour of electricity ($) 1 kwh x 0.06 = $.06 dollars or 6 cents Bulb Location Type of Bulb Wattage Hours of Usage/Day Cost 13

14 Lighting the Way Exhibits Option #1 Make or repair a house lamp. Whether you have decided to remake an old lamp or design a new one, study the next few pages carefully. This information will help you assemble a lamp that you will be proud of for many years. Check each point carefully as you create your lamp. We highly recommended that you attach a note explaining the intended use and any additional information that will help the judge better understand your project. Bulbs The size and type of bulb needed varies depending on the kind of the lamp. If the lamp is to be used for task lighting, such as a reading lamp, a 3-way bulb is recommended. Lamps used for decorative purposes only should use 60-watt bulbs or smaller. Using bulbs over 60 watts in these lamps produces unneeded light and, thus, wastes energy. Shades The lampshade is important in preventing direct glare from the bulb and directing the light from the bulb to the work area. Some important points to remember when selecting a shade are: White on the inside. A white inside causes the light to be reflected out the top and bottom of the shade. Open at the top and bottom. The shade should be open to allow light to exit the shade. Wider at bottom than at top. A wider, larger opening on the bottom than on the top is desirable because the light produced is directed down and out the bottom onto the work area. FOR A STUDY OR WORK LAMP, it is generally recommended that the bottom of the shade measure 16 inches or more across. NOTE: Some shades produced today are the drum type which means they measure the same at the top and bottom. It is okay to leave the plastic covering on the shade for display at the fair to keep it clean. Remove the plastic before using your lamp when you get it home. Socket The socket should be UL (Underwriter s Laboratory) approved. The UL seal means that the socket meets certain safety standards. The lamp switch should be slightly below (approximately one inch) the bottom edge of the shade. Can you explain why the switch should be placed slightly below the shade? Cord The proper size and type of parallel cord is very important. Selecting a cord size that is too small could result in the 14

15 cord overheating and starting a fire. The cord should be: UL Type SP or SPT Wire size #16 or #18 8 to 10 feet long Appropriate color to match your lamp NOTE: The lamp cord should not be brittle and should be free of breaks in the insulation. If the cord is pre-stripped with brass tips, you will need cut off the tips and re-strip. Cord Cap (Plug) The cord cap must contain a handle that can be gripped for plugging and unplugging the cord cap from an outlet. What may happen if the cord cap does not contain a handle? Right people may pull on the cord to unplug the cap from the outlet, and pull the cord loose from the cap. A loose cord cap may result in bare wires, increasing the chance of electrocution and fire. Also note the following cord clamp information: Base Do NOT use quick-snap plugs, insulation displacement, clamp-on plugs and molded plugs that come with lamp kits. Plugs should have screws for attaching the wires. The plug must be UL-approved with a dead front. This means the design, construction, and installation ensure that no current-carrying parts are exposed. A polarized plug is recommended. Include an underwriters knot (Figure 8), cord clamp, or cord maze to help keep the wires secure beneath the screws if the cord is pulled Figure 8. Three steps in tying an Underwriters knot The lamp s base should be heavy and wide enough to prevent easy tipping of the lamp. Also, the base should have felt on the bottom to prevent damage to furniture Use your imagination when designing your lamp s base. It may be round, square, or odd-shaped. You may use a variety of materials, including wood and metal. Some examples of bases are bowling pins, wooden legs of old tables, and football helmets. Whatever you use, the base must be heavy and wide enough to prevent the lamp from tipping easily. At the base of the lamp, or any place the cord goes through a hole, the cord should be protected by a cord bushing or grommet. A cord bushing or grommet is a rubber or plastic protector that slides over the cord to prevent the cord from being cut. 15

16 Lighting the Way Threaded Lamp Tubing One end of the tubing is connected to the base and the other end has the socket connected to it. For reading and study lamps, 1/8-inch pipe approximately 16 inches long, threaded on both ends, may be substituted for lamp tubing. Why should the lamp tubing be about 16 inches long? If you said that a 16-inch lamp tube allows the lamp to be tall enough so that light is projected over the work area, congratulations! You are right. A short tube would result in the shade s bottom being so close to the table that only a very small work area would be lighted. A very long tube would result in the lamp shade s bottom being so high that the light bulb may glare directly into your eyes. In addition to the tubing you need: Two locknuts to fit the threads on the pipe. One bushing to fit the threads on the pipe. The bushing is a plastic nut that prevents the electrical cord from being cut by the pipe s edge. Assembling Your Lamp All lamps are assembled in a similar manner, and the steps are the same for wiring a new lamp as for rewiring an old lamp. Points to remember when assembling a lamp include: Bend the conductors (wire) around the terminal screws clockwise. A clockwise direction allows the conductors to be drawn tighter as the screws are tightened. 2. Leave insulation on the wire to the screw head, but make sure no insulation gets under the screw head. 3. The parallel cord will have a smooth side (the load-carrying or hot wire) and a ribbed side (the non-load-carrying or neutral wire). The ribbed side must be connected to the silver screw in the socket, or the screw that attaches to the shell of the socket. 4. The ribbed wire also must be attached to the plug s silver screw or the screw that attaches to the wide blade of a polarized plug. Insulating Paper Switch Cap Locknut 1/8 Pipe To Plug Harp Brass Shell Body Underwriter s knot Standard of Lamp Goes Here Base of Lamp Goes Here Bushing Figure 9 Grommet Cord 8 to 10 Feet Long Plug Not Molded or Quick-Snap

17 Exhibits Option #2 - Make A Poster You may exhibit a poster that covers any topic in this manual. Your poster may feature pictures, diagrams, written articles, or objects. A poster must be 22 inches x 28 inches, with a solid backing, and must be displayed horizontally. It should be covered with plastic to keep the poster clean while on display. Features of a good poster include: It is creative and promotes new ideas. It attracts attention and stimulates interest. The subject encourages thought and educates the public. Some possible topics include, but are not limited to: Explaining light quantity and quality Discussing light glare, contrast, and shadows Discussing different methods of lighting Talking about light bulb terminology Comparing and analyzing the different types of light bulbs Developing a cost analysis for the different types of light bulbs 17

18 Indiana 4-H Club Record 4-H-1000a-W Electric Project Division IV Name Age Year Name of Club Years in club work Township County Project you exhibited at this year s fair (check one). 1. Made or remade household lamp 2. Poster I have reviewed this record and believe it to be correct. Signature of Leader Date Demonstrations you gave on something you learned in the electric project. Title or subject Given before (check the appropriate responses) Family Friends Class Local 4-H Club County Electric Meeting County Demonstration Contest How many times given? Field Trips Where did you go? With whom? What did you learn? What new things, this year did you learn about electricity? Separate Record Sheet Available at Your County Extension Office and at 18

19 4-H Electric Lamp Check Sheet 4-H-1000b-W Name County Item Comments Electrical Quality Bulb Recommended size and type Wire UL approved, correct size and length Cap (no quick-snap, insulation displacement, clamp-on or molded plugs are allowed) UL approved Properly wired Cord clamp or underwriter s knot Socket UL approved Underwriter s knot Properly wired Safe to use Base Height Proportion Design Cord grommet or bushing Felt or protected base Workmanship Shade Style in keeping with base Color Outer covering Lining Height Top diameter Bottom diameter Total 19

20 4-H Electric Poster Check Sheet 4-H-331-W Name County Item Satisfactory Comments Effective Title Suitable Subject & Size (as outlined in 4-H Electric manuals) Attracts Interest (original, good use of color) Subject (encourages thought) Accomplishes Purpose Mounting on Stiff Backing Workmanship (neat, safe) Placing 20

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24 Lighting the Way Purdue Agriculture New 03/09 It is the policy of the Purdue University Cooperative Extension Service that all persons have equal opportunity and access to its educational programs, services, activities, and facilities without regard to race, religion, color, sex, age, national origin or ancestry, marital status, parental status, sexual orientation, disability or status as a veteran. Purdue University is an Affirmative Action institution. This material may be available in alternative formats. 24 Order or download materials at the Purdue Extension Education Store