For electrical contractors, home lighting can mean much more than just incandescent bulbs and switches on the inside and floods on the outside.
Some upscale homes rely on a suite of electronic lighting controls, dimmers and ballasts and a variety of lamp technologies and fixtures, and some even employ lighting that links to structured-wiring systems, through low-voltage CEBus power-line control.
All in all, today's home lighting offers a tremendous opportunity for electrical contractors to learn about basic lighting-design techniques and new lighting products. Manufacturers now offer various lamps, fixtures and lighting controls to enhance the appearance and comfort of today's homes.
Within a home, light performs four basic functions — it provides decorative, accent, task and ambient illumination — and usually these four functions cannot be properly satisfied by a single light source. For example, a decorative chandelier installed above a dining room table often needs to be complemented by wall sconces or other light sources.
Accent light is directed illumination that highlights objects within an environment. Task lighting handles work-related activities, such as preparing food, reading or folding laundry. Ambient light creates overall illumination and softens shadows within a room. Although it is one of the most important of the four functions of light, ambient light is often omitted in the design of a room or space.
KNOW YOUR LIGHT-SOURCE OPTIONS
While standard line-voltage incandescent and tungsten-halogen (TH) lamps have long been popular for home applications, the TH HIR (Halogen Infrared-Reflecting) lamp provides a new level of energy efficiency. The HIR version redirects heat energy back to the filament through a special coating on a quartz shield surrounding the filament. This combination of a halogen gas “cleansing” and reflective coating nearly doubles the efficacy of the incandescent filament, offering the potential of nearly 40 lumens per watt. For example, at 8 cents per kWh, a 100W PAR lamp operating for a year costs about $70 to operate, while a 60 or 70W PAR HIR lamp lowers this ct by about $25 a year.
Low voltage (LV) lamps are incandescent lamps operating between 6V and 75V. The increased diameter of the filament in a LV lamp means a more compact filament, compared to a 120V lamp. The relatively small filament provides more precise beam control. Thus, LV reflector lamps with narrow beam spreads are the ideal choice to light small objects at close range or larger objects at greater distances.
Three different lines of LV lamps that operate at 12V are the MR, PAR and AR lamps. Using a very compact halogen bulb, MR (miniature reflector) lamps are available in both 1¾-in. (MR11) and 2-in. (MR16) diameters with either a miniature bi-pin or bayonet base. MR 11 lamps come in 12W 20W, 35W and 50W ratings. MR 16 lamps have 20W, 35W, 42W, 50W, 65W and 75W ratings. Both types have a variety of beam widths from narrow spot to narrow and wide flood. Consider a pair of 50W MR-16 NSP fixtures as a way of drawing the eye to a sculpture at the end of a corridor. Some new MR versions minimize color shift over the life of the lamp.
Using screw terminals, the PAR 36 and PAR 56 lamps come with a filament shield, which blocks direct view of the filament and thus provide effective glare control for fixtures that are exposed to view, such as track-mounted heads.
Also using screw terminals, the aluminum reflector (AR) lamp has a pre-focused axial filament lamp and a faceted aluminum reflector that forms an optical system. Identified with millimeter dimensions, the AR lamps are available without a lens in 48 mm, 70 mm and 111 mm sizes, and with a lens in 37 mm and 56 mm diameters. An AR111 lamp is comparable to the PAR36 lamp size and base and thus can be used interchangeably with PAR 36 lamps. For example, a floral arrangement on a table in an entrance foyer can be richly illuminated from a second floor ceiling, 35 ft above, by a few 75W AR111SP lamps.
YOU CAN'T BEAT FLUORESCENT EFFICIENCY
Another area where lamp companies continually add new products is the compact fluorescent (CFL) line. Three to five times more efficient than incandescent lamps and lasting 20 times as long, they come in a range of lumen packages: U-tube, circle, triple/quad tube and D shape. Numerous improvements in manufacturing, along with better managing of ripple currents and control of preheating, result in CF lamps with high-lumen outputs. Examples include 57W (4,300 lumens), 70W (5,100 lumens) and 80W (6,000 lumens). High-lumen biax fluorescent lamps (57W) with a color temperature of 2,700K can look like incandescent, halogen and xenon sources, when used in coves and other architectural features of the home.
Increasingly, contractors install both CF surface-mounted and recessed fixtures in living spaces and hallways throughout the home for dramatic energy conservation. Although the 4-ft, T8 linear fluorescent lamp is the standard today, continuous lamp manufacturing improvements have produced a premium line of T8 lamps, rated at 30W, rather than the standard 32W. At the same time, new ballast designs matched with specific linear fluorescent lamps create optimum systems.
The life of T-8 linear lamps, at three hours per start, is also stretched to 20,000-hours, and, in some cases, even to 30,000-hours. Some manufacturers now offer T-8 lamps with full-rated life on all T-8 ballast systems, and 33% longer life on instant-start ballasts than standard T-8 lamps.
Uniform general lighting can be achieved with a ceramic metal-halide light source in 20W, 39W and 70W ratings. The newest designs have much smaller arc tubes, which provide better control of the metallic salts, resulting in higher light output, better starting characteristics and longer life.
FIXTURES TO KNOW
Electrical contractors can successfully install a variety of recessed luminaires in a home setting. A straight downlight, or direct luminaire, is described in terms of how the internal reflector redirects spreads or concentrates the light, so they are called wide-, medium- or narrow-beam fixtures. Almost all open-reflector downlights have round apertures, with the diameter of the reflector bottom, ranging from 6 in. to 9 in. Generally, look for the smallest diameter fixture opening that will properly handle the desired purpose to minimize ceiling clutter. Some types of downlights using asymmetrical reflectors and lenses achieve a distinctive light beam pattern, rather than a directly down symmetrical light distribution. These are called adjustable accent, wall-washer or downlight/wall-washer.
In addition to lenses, diffusers and louvers are also used to change the beam pattern or to shield the light source from normal view. A dropped diffuser made of opal glass spreads the lamp brightness. A baffle (either black groves in the inner surface of the fixture or a louver) will reduce aperture brightness.
An electrified wireway, or light track, answers numerous lighting requirements in a den, family room or kitchen. The track can be recessed, surface-mounted, stem-supported or attached to a wall. Electricians can add fixtures to essentially change the mood of a room. Experiment with various track heads to get the right look.
Many suspended fixtures, such as pendants, are basically “lighted ornaments.” The installer should separate functional illumination to complement the decorative fixture, whether in a dining room or a stairwell.
LIGHTING DESIGN TECHNIQUES
A good lighting design follows a hierarchy defined by accenting certain areas or surfaces and lowering light levels elsewhere. Lighting designers and electricians can both use various methods:
This technique creates more than five times the brightness on a featured object, compared to the brightness of the background or surrounding area. Low-voltage lighting expands the usefulness of this technique, for example, to focus attention on a painting or a piece of furniture.
This technique provides an even coverage of relatively uniform brightness on a vertical surface. Three effects are achieved:
A directionality is created for the space, since attention is drawn to the brightest wall surface.
Diverse objects on the wall or in some area of the room are visually unified.
A large amount of indirect light is discretely delivered into the space.
Specific techniques include:
In this design, a row of luminaires is installed on centers closer than, or equal to, their distance from the wall. The center-to-center spacing varies with the ceiling height and the light intensity desired on the surface. Incandescent lamps are the source.
Diffuse-source continuous wallwash system
For ceiling heights of 8 ft to 10 ft, a diffuse fluorescent light source is usually specified.
Grazing wallwash system
This technique directs light at a shallow angle on a wall surface. The fixtures are ceiling recessed, or surface mounted behind a valance, about 6 in. to 12 in. from the vertical surface to be grazed. Incandescent or fluorescent light sources are generally used.
To illuminate a heavily textured vertical surface, a point source grazing wallwash system places a row of luminaires about 6 in. to 12 in. from the vertical surface, or wall. Incandescent or low wattage HID lamps are the preferred sources.
One method of lighting artwork would be with recessed 4-in. square MR16 fixed angle wallwashers with 55 deg by 75 deg spread lenses and bent aluminum reflectors. They provide even illumination both horizontally between luminaires and vertically from the top to the bottom of the walls.
Backlighting is a technique that diffuses light through translucent materials, such as acrylic panels, stained glass, silkscreen, marble veneer or other similar materials. Backlighting commonly uses a layout of fluorescent lamps within indirect fixtures.
Uplighting is a technique for illuminating a wall from the floor or lower area, in locations where ceiling-mounted lighting fixtures are not desirable.
Structural lighting involves mounting fixtures within constructions of wood or drywall such as cornices or box beams, used to conceal backlighting, wallwashing, uplighting and grazing light. Cross-section construction drawings usually show the cross-section details and the dimensions of the building materials along with the lighting equipment locations.
To illuminate a structurally created ceiling dome in an entranceway, light strips containing 5W, 24V xenon festoon lamps spaced 2 ft on center are a good choice. These lamps have a higher color temperature than incandescent downlights and leave the impression of a skylight about the dome.
GETTING IT ALL UNDER CONTROL
To make a home more energy efficient, occupancy sensors turn lighting off and on in rooms, or areas, sensing movement for preset periods.
Passive infrared (PIR) sensing devices detect the difference between heat emitted from the human body in motion and the background space. The latest technology ensures higher sensitivity to minor motion without the potential for false activation. PIR devices are available as a wall-switch model (in place of a standard snap-switch at a doorway) or a ceiling-mounted unit.
Ultrasonic sensing devices transmit and receive low intensity sound waves at a frequency of about 25 kHz to 40kHz, which is inaudible to the human ear. Any change in the signal return time is interpreted as motion, allowing the sensor to switch the lighting on.
Dual technology sensing devices combine both PIR and ultrasonic sensing in a single unit, for a room where either technology alone would not work properly. Detection by both types is necessary to turn lighting on, while continued detection by only one technology will hold lighting on.
Outdoor motion sensing devices are generally installed in combination with the lighting fixture being controlled. Constructed to withstand harsh weather, these units are ideal for walkways, garden paths and entranceway illumination.
When fluorescent lamps are operated through occupancy sensors, and thus receive frequent on and off switching, the electrodes at the tube ends wear out at an accelerated rate, reducing their operating life. For that reason, electronic ballast manufacturers have developed a new technique for beginning lamp operation, called “programmed start or programmed rapid start.”
Programmed-start means that the lamp cathodes are preheated for a period of time before the lamp operates, unlike instant start electronic ballasts. By soft starting lamp operation, the life of standard T8 linear fluorescent lamps can be increased to more than 30,000 hours.
Many manufacturers now offer products that control the light levels and create particular scenes within a home. One vendor's system automatically brings all tungsten-halogen lamps to full brightness once a week, which allows the lamps to maintain efficacy and to reach average rated life.
Another option with dimming systems is power-line carrier signal transmission, which transmits signals over existing wiring. These systems also offer programmable lighting scene creation, with multiple dimmers/switchers/master control stations. Line filtering prevents the entry of stray power line control signals, originating from a nearby home.
VERSATILE LIGHTING FOR KITCHENS
Today, kitchens are more than just a place to prepare meals; they are also the center of many family activities, and thus should be given extra attention. Kitchens calls for a versatile lighting scheme, generally consisting of some form of ambient lighting and localized accent lighting for specific tasks or moods.
Usually, a surface-mounted or recessed ceiling fixture for linear fluorescent lamps located in the center of the room provides general lighting. While a 4-ft fluorescent fixture was the choice in the past, more recent design trends favor ceiling-recessed line-voltage or low-voltage fixtures in a planned pattern.
Recessed downlights work well over the stove and sink areas. The kitchen table can be a focal point accented by a single chandelier, or a set of smaller suspended fixtures that serve a similar purpose. Under-counter lighting is a necessity for larger kitchens. Over-cabinet lighting will emphasize tall ceilings.
Localized accent or decorative lighting should be circuited into separate zones. This allows the homeowner to create a particular ambience by selecting various lighting units. Dimmer control of incandescent is desirable. Finding a computer workspace in a kitchen is a new twist, and direct downlights or adjustable spotlighting fixtures can help illuminate paperwork and other reference material kept near the keyboard, the calendar and the ever-present tack board with reminder notes.
WEB-BASED LIGHTING RESOURCES
CEE News' editors spent several hours perusing Web sites that offered online access to training on residential lighting, or information on the many courses in residential lighting design available from manufacturers and other lighting resources. Here are our picks for the most useful Web sites in the residential lighting field.
This lighting-design tutorial site highlights design parameters, technologies and lighting terminology.
This manufacturer of residential lighting fixtures offers classes in residential lighting design at its Riverside, N.J., training center.
In GE Virtual Lighting designer, you can compare different lighting schemes in a house. GE Lighting's Nela Park Lighting Institute in Cleveland, Ohio, is world-famous as a training center.
Operated by interLight.com, one of the largest online lighting resources, this Web site offers design advice and other technical information for residential applications.
Lightolier's Lessons In Lighting
Lightolier offers a free online training course in the fundamentals of lighting.
Osram Sylvania LightPoint
Contractors and other electrical professionals can take multi-day courses at the LightPoint facility in Osram's Danvers, Mass., headquarters.
Philips Lighting and the Lighting Technology Center
Philips Lighting's training center at its Somerset, N.J., headquarters offers intensive lighting training.
Lighting Research Center
Managed by staff and students at Rensselaer Polytechnic Institute (RPI), Troy, N.Y., the Lighting Research Center offers a wealth of technical data on residential lighting, as well as different segments of the lighting field.
Don Klipstein's Lighting Info. Site
This site offers a potpourri of lighting facts, opinions and links.