CHAPTER 1

AREA LIGHTING SYSTEMS

Advancement brings both increased rewards and increased responsibilities. The advantages are obvious-higher pay, greater prestige, more interesting and challenging assignments, and the satisfaction of getting ahead in your chosen career. As a Construction Electrician first class petty officer, you will have many responsibilities added to those you had as a second class petty officer. You have acquired a lot of valuable knowledge, and now it is your turn to pass on the technical know-how of your job to others.

In addition to supervising and training lower rated personnel, you will be required to perform various leadership and administrative duties. The type of activity to which you are assigned will determine just how you carry out your responsibilities, but the ability to apply effective techniques of leadership and to get along with people will help you succeed in the Navy, regardless of your assignment.

These duties and responsibilities are covered in the Naval Construction Force/Seabee First Class Petty Officer Training Manual, NAV-EDTRA 10601.

This chapter covers the streetlighting systems, the floodlighting systems, and the security lighting systems that are required at all military installations. When properly constructed and installed, these original basewide lighting systems will provide years of trouble-free operation with a minimum of minor maintenance and bulb changing required to keep the system fully operational.

Several factors can change the base requirements for area lighting. These factors include such changes as facility usage, updating of systems, changes in the base mission, or expanding existing systems.

With the cost of energy rising daily, any system that can provide a higher level of efficiency for the energy used must be considered. In this area the use of the newer high-pressure discharge systems for lighting seems to offer savings both in the lifespan of the bulbs and in the lumens per watt of energy used. These systems are replacing the older incandescent systems in an ever-increasing pace. The higher initial cost of these systems is being offset by the efficiency of the energy used and savings of energy dollars.

OUTDOOR LIGHTING

There are a number of light systems in use today. They are streetlights, floodlights, and security lights. These systems can be as simple as a few portable floodlights to help accomplish an after-dark-rush job or a base streetlighting system. In this section, we will discuss the lighting system requirements and equipment that is common to all three systems.

LUMINAIRE TYPES AND FIXTURES

While most of us think of streetlights as using incandescent bulbs, the first electrical streetlamps used arc lights. While the quantity of light produced was sufficient, the brightness, color, cost, and maintenance of the system presented problems that were unacceptable. With Edison's invention of the incandescent bulb, electrical lighting became a practical way of life. While the incandescent bulbs are still in use and solved many problems, they have created some new problems.

Aging is one of the primary problems of incandescent bulbs. Two factors are involved. Both of these factors concern the tungsten filament. When the filament is heated, part of the metal is driven off by thermionic emission and is unable to return to the filament. This metal collects on the inside of the glass bulb causing the glass to darken and reduce the light rays that can be passed through the glass to provide light. Metal that is lost from the filament reduces the size of the filament. This reduction in size increases the resistance and thereby reduces the light produced. Over the lifespan of an incandescent bulb, it may lose as much as 30 percent of its ability to deliver light because of these two factors.

Electric-Discharge Lighting

Efforts to improve the power efficiency and reduce the maintenance costs led to the development of a new family of lighting which has been generally categorized as the electric-discharge lamps. These lamps all have a negative resistance characteristic. This means that the resistance decreases as the lamps heat up. This would normally cause the current flow to increase. Each lamp of this type must be equipped with a currentlimiting device called a ballast. Lamp life and more light per watt are two main advantages that electric-discharge lamps have over incandescent bulbs. The basic types of electric-discharge lamps used in area lighting are vapor, metal halide, and fluorescent lamps.

Figure 1-1 shows the basic configuration of vapor and metal halide bulbs. In these lamps, a material, such as sodium, mercury, or metal halide of thallium, sodium, or indium, in addition to mercury, is added to the arc tube. In design, the lamp has three electrodes, with one electrode being used only for starting. The arc tube contains small amounts of pure argon gas to aid in starting. Free electrons are accelerated by the starting voltage. In this state of acceleration, these electrons strike atoms and displace other electrons from their normal atomic positions. Once the discharge begins, the enclosed arc becomes the light source. The addition of the metal halides to the arc tube results in a bulb with a 50-percent higher efficiency and a better color quality than the mercury arc bulb. In the past, the main drawback of sodium lights has been the poor color quality of the light produced. The new highpressure sodium light is smaller and has a better color. This light has a higher light-producing efficiency than does any other commercially produced white light source.

Commercial companies that produce these light bulbs claim a 100-percent increase in lamp life over tungsten filament bulbs that produce the same amount of light. The power in watts required to operate these lamps is less than one-half that required for filament lamps. The initial cost of the components for lights is substantially greater as these lights will require ballasts; however, this cost can be made up later by the savings of energy costs. The selection of lighting fixtures will depend on budgeted dollars for new installation projects versus maintenance dollars.

Most discharge lighting fixtures are supplied with the required ballast installed in the fixture.

Figure 1-1.\Vapor and metal halide bulb configuration.

In some cases ballasts, usually called transformers, are externally installed.