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Industrial Lighting

Introduction

Lighting is necessary in every workplace to ensure a safe and productive environment. In situations where natural lighting is not sufficient, electrical lighting must be supplemented. Electrical lighting can be divided into three categories: general, supplemental, and emergency lighting. General lighting produces uniform light levels throughout the entire facility. Supplemental lighting provides more intense light levels for small areas or workstations that general lighting cannot provide. Emergency lighting is used when electrical power is disrupted. It can take the form of battery- or generator-powered systems. All three categories of lighting use the same principles, highlighted in this document.

Terminology

Amperes (Amps): A measure of electrical current. It can be compared to water flow in a water line. 
Averaged Rated Life: The median time it takes a lamp to burn out. Based on continuous laboratory testing, the average rated life is the point when 50% of the test samples have burned out and 50% are still burning. 
Ballast: An auxiliary piece of equipment designed to start and properly control the flow of power to gas discharge lights such as high intensity discharge (HID) or fluorescent. 
Candlepower: A measure of the intensity of light that lamps project. 
Footcandle: A unit used to measure how much total light is reaching a surface. One footcandle falling on one square foot of surface produces illumination of one footcandle. 
Glare: Brightness that causes discomfort, annoyance or eye fatigue, interfering with vision. 
Lumen: International (SI) unit of the quantity of light or luminous flux. 
Lux: International (SI) unit of illuminance. One lux is equal to 1 lumen per square meter. 
Voltage: A measure of electrical pressure or electromotive force. It can be compared to pressure in a water line. 
Wattage: A measure of electrical power. In lighting it reflects the amount of power consumed by the bulb. The multiplying voltage derives it by amperage.

Lamp Types

Incandescent
Incandescent lamps are the most familiar type of light source. They generate light using a thin filament wire that creates a white heat by an electric current passing through it. Incandescent lamps are all-purpose lamps and can be used for general, supplemental or decorative lighting. They provide a true to life, warm coloring with an energy efficiency up to 18 lumens per watt. They are available in a variety of styles including standard bulbs, tubular, reflective spot and flood lamps, decorative bulbs, three way or rough-service bulbs. A typical life can range from 500–1000 hours and long-life bulbs can last up to 2000 hours. Incandescent bulbs are readily available in stores, are easy to install and their life is not affected by switching them on and off.

Halogen
Halogen lamps generate light by using a thin filament wire enclosed in a quartz tube that contains a pressurized gas such as halogen, iodine or bromine. This design allows the bulb to burn hotter which produces a whiter, brighter light more efficiently than an incandescent bulb. Halogen bulbs are used for accent lighting, display lighting, outdoor floodlamps and automobile headlights. They are available in a variety of styles including single and double-ended quartz, reflective spots and floods, parabolic aluminized spots, floods and mini-can bulbs. They have a typical life range from 2000–5000 hours. Halogens provide a brilliant white light with an energy efficiency up to 22 lumens per watt. The bulbs come in compact sizes, do not blacken with use and provide an intense, focused light.

Fluorescent
Fluorescent lamps create light by passing an electric arc through an inert gas. The heat generated from the arc vaporizes tiny drops of mercury which emit ultra-violet (UV) light. The released UV light stimulates a phosphor coating on the inside of the glass bulb, glowing brightly in all directions. A ballast is required to heat the bulb electrodes on initial start-up, then regulates the power flow to keep the lamp burning. Fluorescent lamps excel at providing high levels of general lighting very efficiently. They can last 10 to 20 times longer than an incandescent light and use one-fifth to one-third the electricity to generate the same brightness. They are available in several styles such as u-shaped, circular and straight tubes up to 96" long. The typical life range is from 12,000–24,000+ hours, with an energy efficiency up to 105 lumens per watt. A drawback to fluorescent lights is that they can only be dimmed with expensive special equipment and are sensitive to cold temperatures.

Compact Fluorescent
Compact fluorescent lamps operate in a similar fashion as linear fluorescent lamps. These lamps are designed for use in standard incandescent sockets and serve as energy-saving replacements to incandescent lights. They are available in bulb, circular or twin-tube configurations. A typical life ranges from 9,000–10,000 hours with an energy efficiency up to 105 lumens per watt. They have color similar to incandescent lights, last 9 to 13 times longer and save 64% to 82% in energy consumption compared to incandescent lights. To maximize the life of the bulb, compact fluorescent must be used in locations where they stay on for several hours at a time. No lamp dimming is possible.

High Intensity Discharge
High intensity discharge (HID) lamps generate light by passing electrical current through an internal tube filled with a blend of gases under pressure. Electricity through the tube is regulated with a ballast in similar fashion of a fluorescent lamp. HID’s are powerful light sources used for general area, landscape or outdoor floodlighting. Three types of HID lighting available include mercury, high-pressure sodium and metal halide—all in a screw-base bulb. Typical life ranges from 10,000–24,000 hours, with an efficiency of 65 to 140 lumens per watt. These lamps are the most energy efficient bright lights that provide long life in hot or cold environments. HID’s take a few minutes to warm up as they gradually reach full brightness.

Cost of Operation

The cost of light is not only reflected in the cost of the light bulb itself, but in the installation and the electricity the bulb uses. Electricity accounts for the greatest share at approximately 80% to 88% of the cost. The cost of labor to install the bulb is approximately 8% while the cost of the bulb is around 4% of the total cost. Purchasing the most energy efficient lamps with the longest life possible will save a great deal in electricity costs and labor costs. For instance, purchasing a compact fluorescent bulb rather than an incandescent bulb will be more expensive initially; however, the savings in labor and especially the savings in electricity will greatly reduce your costs overall.

The national average cost of energy is between 8 and 10 cents per kilowatt-hour (kWh). To calculate your average energy costs, use the following formula:

Bulb power (Watts) x Bulb average life x Cost per kWh/1000 = Cost of Electricity

Light Level Recommendations

The amount of light required for any space depends greatly on what activity is taking place in the space. Providing too little light reduces productivity and accuracy while too much may cause discomfort or eye fatigue. The following light level recommendations are for area, office and industrial lighting.

*Higher illumination may be achieved through general and supplementary lighting.

Color of Light

The color of light created by a light bulb effects how people and objects look. The higher the color-rendering index (CRI), the better that bulb will make objects appear. A color rendering of seventy or more is best. Another consideration is the amount of “warmth” or “coolness” of the bulb. A warm bulb gives off a yellow-white light, while a cool bulb gives off a white light on a neutral surface. Incandescent and warm fluorescent bulbs generally strengthen red, orange, yellow hues while weakening blue hues. Cool fluorescent bulbs generally strengthen orange, yellow and blue hues and weaken red hues.

Commonly Asked Questions

Resources

Fundamentals of Industrial Hygiene, 3rd Edition; National Safety Council

Home Lighting Handbook, General Electric Company; 1992 

GE Lighting 9200 Lamp Catalog, General Electric Company; 1995 

Sper Scientific Product Manuals

ANSI/IES RP-7-1983, American National Standard Practice for Industrial Lighting, Appendix A

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