Selecting the Right Light for the Right Purpose

by DoItYourself Staff

Light Bulb Safety Tips

Incandescent bulbs turn black as they near the end of their lifetimes. Customers should consider replacing darkened bulbs, as they use the same amount of electricity to produce less light.

To save energy, customers can do the following to economize on the lighting portion of a electricity bill: use dimmers, Use photoelectric cells or timers to turn off outdoor lights automatically, use reflector bulbs for task and accent lighting, use energy saving fluorescents where practical.

Incandescent Bulb

Produce light by passing current through a thin coil of wire called a filament. As the wire heats, it becomes white hot and emits visible light. Vacuum filled.

Use for general and task lighting around the house.

Wattage indicates the amount of electric power used by a bulb to produce light. Generally, the greater the wattage, the greater the light output. Some bulbs produce more light per watt than others.

Standard household bulbs have an average life of 750 to 1,000 hours, which can be lengthened or shortened by the treatment they receive. For example, a 120V bulb operating on a 125V circuit may produce more light but won’t last as long as one on a 120V circuit.

Underwriters Laboratories (UL) tags on fixtures designate the maximum allowable wattage. A mercury or fluorescent system is typically limited to a single bulb size.

Long-life bulbs may last longer than ordinary bulbs, because they have heavier filaments that do not burn out as quickly. However, these bulbs do not produce as much light as standard bulbs

Manufacturers disclose average light output (in lumens) and average bulb life (in hours) on package labeling.

The filament vaporizes as a result of current flowing through it, and generally, the bulb “burns out.” Three-way bulbs lose two light levels when one filament burns out because two filaments are used in the bulb separately for two of the levels and together for the third.

Bulb designations denote size and shape. The figure following the bulb shape letter designation is the bulb’s maximum diameter in eighths of an inch. Thus, A-19 would mean an A-shaped bulb with a diameter of 19 x 1/8", or 2-3/8".

Most standard bulb envelopes are made of lime glass, but bulbs that must withstand greater heat are made of harder, heat-resistant glass. Hard-glass envelopes are used in many high-wattage bulbs and in bulbs recommended for outdoor use where there is danger of thermal shock from condensation.

Halogen Bulb

Like incandescent bulbs, halogen bulbs produce light by passing current through a coiled tungsten wire. The tungsten wire is enclosed in a small quartz or high-temperature glass tube, which is then filled with gases, including a halogen gas.

The advantages of tungsten halogen bulbs compared with standard incandescent bulbs include less loss of light over lamp life; smaller physical size for better directional light control; whiter, brighter light; more light per watt; and longer life.

Like incandescent bulbs, halogen lights have the advantage of instant-on light. They are easy to use with dimmers for energy savings.

Typical halogen lamps last 2,000 to 4,000 hours compared to 750 to 1,000 hours for incandescent lamps. Wattage levels for home use run from 5 watts to 500 watts.

More energy-efficient than standard incandescent bulbs. They generate up to 30 percent more light for the same electricity.

Halogen bulbs blacken much less than incandescent bulbs and stay brighter as they age. Because of their brilliant white light, they are excellent for use in displays.

Advise customers not to touch the glass on halogen bulbs

Fluorescent Bulb

Current flows through an atmosphere of inert gas and mercury vapor, producing ultraviolet energy that is invisible to the human eye. A phosphor coating on the inside of the tube transforms the ultraviolet energy into visible light.

Fluorescent bulbs can vary from straight tubes 6" to 96" long to U-shaped tubes and circular tubes. Wattages for home use range from 4 to 75 watts.

Tubes also come in a variety of diameters. Several common types are available in reduced-wattage versions that consume 15 percent to 20 percent less energy. The most common tube is the 1-1/2" used in most bulbs from 15" to 96" long. The smallest diameter is 1/2", used in low-wattage twin tube designs. The largest is 2-1/8" used for some high-wattage, non-residential installations.

Produce up to 105 lumens per watt, compared with a 100-watt, type A incandescent, which produces around 18 lumens per watt.

Features include a long lamp life, relatively low brightness and low heat content and glare, compared with incandescent lamps.

Fluorescents work well for area lighting, especially in kitchen, bath and task areas.

Available in many shades of white and colors. Color is determined by the type of phosphor used in the bulb. Soft white fluorescent bulbs are recommended for living areas, baths and kitchens since they offer good color rendering. Warm white bulbs are good for living areas, although not in areas where color discrimination is important. Cool white bulbs are used for work areas.

Use a ballast. Dim only with special equipment that is relatively expensive. Standard household fluorescents are also sensitive to temperature, and therefore work best indoors. High-output fluorescents are for outdoor use and commercial application.

Ballasts have sound ratings— “A” is the quietest; “C” is the loudest. If a customer is complaining about the noise made by a fluorescent bulb, suggest replacing the ballast.

Electrical connections to the bulbs are made to the bases at each end. The most common is the two-pin base, designated miniature bi-pin for small diameter bulbs, medium bi-pin for average size bulbs and the mogul bi-pin for industrial bulbs. Single-pin bases are used for instant start bulbs, and recessed double contact bases are used on rapid–start bulbs longer than 48".

Compact Fluorescent Bulb

Compact fluorescent bulbs offer different style and performance from standard fluorescent bulbs. Their color nearly equals that of Soft White incandescents, and they offer superior energy efficiency and long life.

Can be as small as 4.5" long, and some are the same size as their incandescent counterparts. Not all fixtures designed for incandescents may have enough room inside the shade or glass for the bulb.

Cannot be dimmed. Their life will be maximized if they are used in locations where a light stays on for hours at a time.

Reflector-shaped compact fluorescents can replace standard R30 and R40 shaped incandescent reflector bulbs.

Globe-shaped compact fluorescents can replace standard G25 bath and vanity globes or G30 decorative globes that are used in pendants.

Decorator or flame-shaped bulbs can replace similar incandescent bulbs in chandeliers, sconces and outdoor fixtures.

Stick-shaped compact fluorescents can replace standard Type “A” bulbs in portable lamps.

Twist-shaped compact fluorescents can replace standard Type “A” bulbs in virtually any application.

When choosing a compact fluorescent bulb to replace an incandescent bulb, compare the lumen output of the two bulbs. For maximum energy efficiency, select a bulb with the highest lumens and lowest wattage combination. For example, replace a 100-watt incandescent household lamp that produces 1600 lumens with a 25-watt compact fluorescent lamp that also produces 1600 lumens.

High Intensity Discharge Bulb

Produces light when current flows through a conducting gas. Uses ballasts to start the bulb and to control its operation. Unlike fluorescent, most of the light comes from the arc itself rather than through the work of the phosphor.

Used primarily for area and security lighting. They feature a lifespan of 20,000 to 24,000 hours. They come in a variety of shapes and in medium and mogul bases.

One type is the mercury vapor lamp. These are used for exterior area and security lighting, such as dusk-to-dawn residential lighting. Mercury vapor lamps provide twice the light output per watt as incandescent lamps. Along with the higher output, they also have a longer lamp life, in some cases up to 30 times as long. They are also more expensive than incandescent or fluorescent. Mercury vapor bulbs produce a bluish white color. Self-ballasted mercury lamps can be used with a ballast in incandescent fixtures and are available for 120V systems in the lower wattages (up to 250 watts) and for 240V systems in both lower and higher wattages. These lamps deliver slightly more light output per watt as the incandescent lamps but have the long life of mercury lamps.

Metal halide lamps feature medium efficiency, with 50 to 110 lumens per watt. They provide good color characteristics (similar to cool white fluorescent lamps) along with higher light output.

High–pressure sodium lamps provide even higher light output per watt than metal halide (50 to 150 lumens per watt), with a golden yellow light. Residential applications include security and landscape lighting.

Low–pressure sodium bulbs feature the highest efficiency, with 100 to 180 lumens per watt. They produce an orange light.

When replacing HID bulbs, you must replace it with exactly the same type of bulb.