Best Practices Guide to Lighting for Building Interiors
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Interior lighting: types, choices, installation, measurements, standards, recessed lighting, kitchen & bathroom lighting
Definition & uses of ambient lighting & task lighting
Explanation of uses of accent lighting & decorative lighting
Definitions of common lighting terms & bulb types
Tables of recommended lighting levels indoors
Uses & properties of incandescent, halogen, low-voltage, and fluorrescent bulbs, lamps, and lights indoors
Explanation of Color Temperature and CRI for Indoor Lights & Bulbs
Definition & Use of Luminaires & lighting fixtures by fixture type: direct lights, indirect lights, accent lights, recessed lights, etc.
Guide to Lamps (Bulbs) Used with Recessed & Track Lights
Guide to types of recessed light (pot lights) housings & their applications
Lighting safety rules for closets - avoid a fire
Lighting guidelines for kitchens
Lighting guidelines for bathrooms
Example photographs of types of interior lighting used by Frank Lloyd Wright, Taliesin West
Where to buy products for building interiors: manufacturers, industry associations
Questions about interior lighting choices, design, installation, specifications & requirements or codes

Guide to buying, installing, & troubleshooting interiour building lighting. This article series details guidelines for selecting and installing interior lighting to meet the requirements for different building areas.

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Choosing & Installing Interior Lighting: Best Practices Guide

This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.

With the exception of purely decorative lighting fixtures, all lighting fits into one of three main categories: ambient, task, and accent. Most rooms use a mixture of lighting types to create visual interest and to meet the functional needs of the space.

A space lit only by indirect light sources can seem visually flat, while a space lit only by directed light from spots and floods can seem harsh and cast dark shadows.

Similarly, a space lit only by accent lighting can look like an art museum and leave people in the dark. A balanced combination of strategies works best.

Our page to photo (Taliesin West, Scottsdale, AZ, D Friedman) illustrates two of several indoor lighting methods used by Frank Lloyd Wright in "the bunker", originally a storage room, currrently used for meetings, and built with no windows. Our photo (above left) illustrates lighting in the lobby of the New York Metropolitan Opera building in New York City.

What Is Ambient Lighting

Ambient lighting is the general background illumination that is bright enough to allow people to move about safely and perform simple tasks. Ambient lighting can be achieved by directly lighting the lower part of the room (direct lighting), or by reflecting light off the ceiling and upper half of the room (indirect lighting).

Our photo (left) shows how Frank Lloyd Wright took advantage of natural lighting thorough a translucent roof at Taliesin West in Scottsdale, AZ. The original roof was white canvas.

Reflecting light upward off the ceiling and upper walls tends to give a room a spacious feeling and soften shadows on objects and faces. It can be achieved with built-in coves, wall sconces, and pendants that direct light upward, or freestanding torchiere-style floor lamps.

Lighting just the lower part of the room can create a more intimate feeling. Options include recessed lights and wall and ceiling fixtures that direct light downward. Fixtures with diffusers will help prevent glare. Evenly illuminating a wall with downlights called “wall washers” is another way to provide soft ambient light and also makes a room feel larger. Many surface-mounted and hanging luminaires project light in more than one direction, providing both uplighting and direct lighting in a single fixture.

Definition of Task Lighting

For details see Task Lighting, Definition , Uses

Task lighting is bright light directed to a specific surface, like a countertop or desk, to illuminate activities such as reading, homework, meal preparation, or laundry. For reading and desk work, task lighting should be bright and well diffused and come from the side or from over the shoulders.

Overhead light often casts shadows from a person’s head and body onto the work surface. Also, light from directly overhead or in front of a person is prone to cause glare (veiling reflection) on shiny work surfaces, such as a glossy magazine. Light coming from one or both sides of the work reduces glare. For example, a table or floor lamp on the side is effective for reading or desk work.

Under cabinet lighting can also be effective for desk work if placed toward the front of the cabinet on either side of the occupant (see Figure 5-22).

Where a computer screen is used, avoid bright sources of overhead light that reflect off the screen. Also keep the screen at right angles to windows if possible to avoid glare. For kitchen work, laundry, or hobbies, concentrated light from above can be effective as long as the fixtures are placed so the occupants do not shade the work surface. Under cabinet lighting is another effective strategy for placing bright task lighting on a kitchen counter or workbench.

Explanation & Uses of Accent Lighting

Accent lighting, sometimes called “object lighting,” directs light to specific objects, such as artwork, furniture, plants, or architectural features. When lighting a single object or work of art, use a directional source, such as a PAR (parabolic aluminized reflector) or BR (bulged reflector) lamp in a track, or an adjustable recessed fixture, such as an “eyeball.” Position the fixture so the light strikes the wall at a 30-degree angle from the vertical.

When lighting a large picture or grouping of pictures, it is often best to illuminate the entire wall section with a wash of light from multiple track lights or adjustable recessed fixtures.

For consistent lighting across the wall without a “scalloping” pattern, use special “wall washer” fixtures or non directional lamps (A-bulbs or compact fluorescent's) to diffuse the light beams (Figure 5-23).

Definition & Uses of Decorative Lighting

Decorative lighting includes candlestick chandeliers and sconces, decorative table lamps, and other fixtures whose main function is to provide luminous “sparkle” to a room.

Definitions & Glossary of of Common Lighting Terms

Our photo (left) illustrates interesting recessed lighting in the Bard Center, New York City.

Ballast: A device that regulates the flow of electricity to start and operate fluorescent and other discharge type lamps.
Beam angle: The angle of the central cone of light (the beam spread) cast by a reflector-type lamp, beyond which the beam intensity is less than 50% of the maximum. Generally, a lamp with a beam angle of less than 25 degrees is considered a spot; with an angle greater than 25 degrees, a flood.
Diffused light: Light that is dispersed in a wide pattern with no directional quality, similar to outside conditions on an overcast day. Glare is reduced, but such light may tend to wash out and flatten objects.
Diffuser: A glass or plastic lens over a lamp that scatters light in all directions. In fluorescent downlights, a plastic or metal grid is often used to block glare and direct the light downward. Deep-cell parabolic louvers are the most efficient grid configuration.
Efficacy: The light output of a lamp per electricity consumed, expressed as lumens per watt. Fluorescent's are three to five times more efficient than standard “A” lamp incandescent's.
Footcandles: A measure of the total light falling on a surface. One footcandle (fc) is equal to one lumen per square foot, originally based on the illumination of one candle held one foot from a surface.
Lamp: A light bulb or fluorescent tube. Types of lamps are explained at Lamp & Bulb Abbreviations & Type and at Lamp & Bulb Types, Indoor
Lumens: A measure of the light output of a lamp (light bulb) or other light source. A candle provides about 12 lumens, a 60-watt soft light bulb about 850 lumens. Details are at Lumens, Definition, comparisons.
Luminaire: Any lighting fixture or built-in lighting system, such as a cove or valence.
Wattage: A measure of the energy consumption of a lamp or other electrical device. More efficient lamps produce more lumens for the same wattage consumed.

Guide to Recommended Lighting Levels Indoors

For details see Guide to Recommended Lighting Levels for Indoor Areas, Tables & Rules of Thumb for Interior Lighting

Many factors affect the illumination needed for a specific task. An often overlooked factor is the age of the occupants. At 60 years old, we need two to three times the light we needed at age 20, and also more shielding and diffusers since older eyes are more sensitive to glare. The other main factors in determining lighting requirements are how detailed the work is and the level of contrast and reflectance of the work surface.

Table 5-21 below shows the recommended lighting along with common strategies for each type of room. For task lighting, the low numbers in each range represent the light needed for simple tasks with high contrast (reading large black type on white paper). The high number is for tasks with more detail or lower contrast (reading the newspaper). For very detailed, low-contrast work or for older persons, light levels of 100 footcandles are often needed.

Table 5-21: Suggested Lighting Strategies and Lighting Levels by Room Type (C) J Wiley, S Bliss

Interior Lighting Rules of Thumb

Also see Guide to Recommended Lighting Levels for Indoor Areas & Tables & Rules of Thumb for Interior Lighting

The illumination level on a surface depends on many factors, including the colors of the room and furnishings and the type of lamp and fixture. High ceilings, dark colors, and diffusers on fixtures all reduce light levels.

The commonly used black baffles in recessed lights reduce output by up to 40%. Tightly focused spots produce much higher light levels than wide floods. The distance from the light source is also critical. Doubling the distance to a lamp reduces the lighting level by a factor of four. So moving the light closer to the task is often the simplest way to provide a big boost in lighting levels.

As a starting point for design in kitchens, baths, home offices, and other brightly lit spaces, provide at least 2 watts of incandescent light or 3/4-watt of fluorescent light per square foot of floor area.

In larger spaces, using multiple fixtures will provide more even lighting and reduce glare. Also, since lighting needs change throughout the day with changes in daylight and usage, it is good to provide flexibility by separately switching groups of lights and adding dimmers. Increase these minimums by 50 to 100% for:

Valences or other indirect lighting schemes
Rooms with dark surfaces
Lighting placed in cathedral ceilings or other high ceilings
Recessed lighting with diffusers, black baffles, or other light-blocking trim. (also see recessed lighting use outdoors, discussed at LIGHTING, EXTERIOR GUIDE)

Lamp Types & Types of Bulbs for Indoor Lighting

For details see Lamp & Bulbs Types, Indoor

There is a vast array of choices in light bulbs, known in the lighting industry as “lamps.” For residential lighting, the main choices are incandescent, halogen, low-voltage, tubular fluorescent, and compact fluorescent. Which lamp to choose for a given application will depend upon the amount of light needed (lumens), color of light desired, type of fixture (luminaire), and whether the application calls for a directed beam or a diffused light source.

Table 5-22: Table of Equivalent Light Outputs Between Compact Fluorescent Bulbs and Standard Incandescent light bulbs (C) J Wiley, S Bliss

Table Comparing Fluorescent bulb Light Output to Standard Incandescent Light Bulb Output

Also, some lamps are more energy-efficient, providing more lumens for the same amount of electricity consumed.

Fluorescent's are the most efficient, using up to 70% less energy than an equivalent incandescent bulb (see Table 5-22).

Incandescent Light Bulbs

Incandescent light bulbs include the familiar non directional “A” lamps, as well as a variety of directional flood and spot lamps designated by an “R” or “BR.” Incandescent's. have a low color temperature of around 2700 K, which produces a warm light with lots of red and yellow tones that make skin, natural wood, and other warm colors look good.

To some extent, things look good to us under incandescent light because it is what we are most accustomed to. Incandescent lamps are inexpensive and are easy to dim, but they are also the least efficient type of bulb and the shortest lived.

Halogen Lights for Use Indoors

Halogen bulbs, also known as tungsten-halogen, is actually a kind of incandescent with more blue and less red light (3000 K), giving it a whiter appearance than standard incandescent lamps. Halogen lamps provide good color rendition and good light for reading and fine detail work. When dimmed, however, halogen light becomes more yellow, like standard incandescent lighting. Also, dimming can cause a halogen lamp to darken due to tungsten evaporation. Turning the lamp to full illumination for about 10 minutes will restore its full power.

Halogen lamps tend to be smaller, produce 10 to 15% more lumens per watt than standard incandescent's., and last about twice as long. They come in a wide range of beam spreads and wattages. However, since halogen lights burn very hot, they must be shielded from contact with other materials or they can create a fire hazard.

Also, the bulbs should not be touched without wearing a glove (since the oil from your skin can create a weak spot on the bulb), and should be cleaned with alcohol. Halogen PAR (parabolic aluminized reflector) lamps are enclosed in a protective glass casing, which allows them to be handled like ordinary bulbs.

Low-Voltage lamps are tungsten-halogen, incandescent, or the newer xenon lamps, operating at 12 volts DC. Their small size makes them ideal for under cabinet lighting, and their very precise beam control makes them well-suited to accent lighting of artwork. Many low-voltage fixtures allow the lamps to rotate within the housing to precisely aim the beam.

Low-voltage Lighting Guide for Building Interiors

Low voltage lights use a step-down transformer to convert 120V line voltage to 12 volts DC. Most newer fixtures use solid-state electronics, which are more energy efficient and longer lasting than the older magnetic type. Transformers are either attached to the fixtures or installed remotely.

Since the transformers, as well as the lamps and dimmers, emit a slight hum, remote location can be an advantage. However, locating the transformer too far from the fixtures can result in a loss of power and dimming of the lamps. When using dimmers with low-voltage lighting, make sure they are specifically designed for low voltage systems and for the specific type of transformer.

Fluorescent Lighting Guide for Indoors

Fluorescent bulbs or lamps produce light by energizing the phosphor coating on the inside of a glass envelope. A device called the ballast regulates the power needed to start the lamp and keep it going. Older magnetic ballasts caused humming and flickering, but new electronic or solid-state ballasts have eliminated these problems.

Fluorescent's produce three to five times the output as incandescent lamps [per watt of energy used], last about ten times as long, and stay very cool. Because they reduce lighting bills by as much as 75%, and reduce cooling loads as well, they are heavily promoted by model energy codes and mandated in some areas. For example, the California Energy Code requires that the main lighting in kitchens and baths be fluorescent.

The downside of fluorescent's has always been their poor color rendering. Standard fluorescent's emphasize the blue range of the spectrum, giving skin an unflattering, pale appearance. Manufacturers have worked hard over the years to improve the light quality. So-called “deluxe” fluorescent's offer CRI (color rendering index) values in the 85 to 90 range but with a 25% loss of efficiency. To achieve CRIs in the high 90s without sacrificing energy efficiency, manufacturers use more expensive rare earth phosphors, creating triphosphor and quad-phosphor lamps.

Fluorescent lamps with high CRIs, and color temperatures within the range of 2700 to 3500K, create pleasing light for skin tones and natural wood and can blend in with incandescent lighting. In applications where color accuracy is important, such as laundry areas, lighting artwork, and certain hobbies, full-spectrum daylight lamps may be preferred. These lamps, which produce light similar to natural daylight, include General Electric’s Chroma 50 and Chroma 75.

Dimming also used to be a challenge with fluorescent's However, using solid-state dimming ballasts and special dimmers designed for fluorescent's can eliminate any humming sounds. These also allow a single dimmer switch to dim groups of fixtures with different length tubes.

Guide to Using Compact Fluorescent Lights

Compact fluorescent lights have created a lot more flexibility, allowing fluorescent's to be used in recessed downlights, wall sconces, pendants, and just about any type of luminaire. Early compact fluorescent's were noisy, slow to start, and had a limited selection of color temperatures. Newer products, however, are quiet and typically have rapid-start ballasts. Dimmable ballasts are also available for compact fluorescent's, but are costly. As with tube fluorescent's, look for high CRIs and lower (warmer) color temperatures from 2700 to 3500K to blend in with incandescent and halogen lighting. All compact fluorescent's have a minimum 80 CRI.

While some compact fluorescent's have been introduced that mimic R and PAR-type reflector bulbs, directional lighting is best achieved with incandescent or halogen lamps. Fluorescent's are better used for ambient lighting, indirect lighting, and lighting of closets and storage areas. Although they cost $5 to $20 per bulb, depending on the wattage and configuration, they generally pay for themselves within two to three years in both energy savings and longevity of the bulbs.

Definitions of Common Lamp (Light Bulb) Abbreviations & Types

For details see Lamp (Light Bulb) Abbreviations & Types

There are literally thousands of lamps to choose from, but the most common in residential lighting are standard incandescent A lamps, 120-volt BR and PAR directional lamps, and low-voltage PAR and MR lamps, along with a variety of tubular and compact fluorescent's.

While different lamp manufacturers use different codes and abbreviations to label their lamps, most list the wattage first, followed by the bulb shape, width of the bulb (in eighths of an inch), and additional information about the shape and beam angle. For example, a 50PAR36/H/NSP8° is a 50-watt PAR lamp, 36/8 (4 1/2) inches across, halogen with an 8-degree narrow spot beam. Common abbreviations include the following:

A: General incandescent.
BR: Incandescent, bulged reflector lamps, which replaced the older “R” lamps. These produce up to twice the light in footcandles on the subject as A lamps.
F: Fluorescent.
G: Globe, incandescent.
H: Halogen.
IF: Inside frost.
MR-16: Multifaceted reflectors – low-voltage halogen lamp with faceted mirrors that provide superior beam control. Available in numerous beam widths.
NSP: Narrow spot.
PAR20, 30, 38: Parabolic aluminized reflector—A halogen lamp protected by a heavy glass lens. PAR lamps provide excellent beam control and produce up to four times the light on the subject as A lamps.
PAR36: Low-voltage halogen lamp with superior beam control over longer distances.
R: Reflector.
SB: Silver bowl, which indicates that the bottom of the lamp is opaque and reflects the light upward.
T: Tubular fluorescent.
VWFL: Very wide flood.
WSP: Wide spot.
WFL: Wide flood.

Explanation of Color Temperature and CRI for Indoor Lights & Bulbs

Also see Color Temperature and CRI for Indoor Lights
Color Temperature Bulb Comparisons

Color temperature and color rendering index (CRI) are two different ways to characterize how colors appear under a light source. Color Temperature is expressed in degrees Kelvin, and for incandescent lights equals the temperature of the metal filament. For fluorescent's and other bulbs without filaments, it is the theoretical equivalent temperature.

Lower color temperatures indicate “warmer” light with more yellow and red tones, which complement skin and natural wood finishes. Higher color temperatures indicate “cooler” light with more blue and green tones, which renders faces harshly and tends to make skin look pale (Table 5-23).

Table 5-23: Color Temperatures of common lamps (bulbs) (C) J Wiley, S Bliss

Skin tones look best under lamps rated from 2700K (standard A-bulb) to 3500K and with a CRI over 80. Residential lamps range as high as 7500K for continuous spectrum fluorescents, such as GE’s Chroma 50 or 75. These simulate daylight and are good for detailed work where color accuracy is critical, but they give skin an unflattering greenish tone.

Definition of CRI Scale Rates Accuracy of Lighting from Various Bulb Types

CRI is a rating on a scale of 1 to 100 of how accurately a lamp shows colored objects. The higher the CRI, the closer the colors look to a standard reference. For incandescent lamps and all others with a color temperature of 5000K or less, the reference is an incandescent or halogen bulb, which are both assigned CRIs of 100. For lamps with a color temperature of over 5000K, the reference is natural daylight, which also has a CRI of 100.

CRI numbers are best used to compare lamps with color temperatures within about 300K of each other. Colors will look very different under a 3000K lamp and a 6000K lamp with the same CRI.

Definition & Use of Luminaires

Also see Luminaires, Definition, Uses

While there are thousands of different luminaires on the market, they all fall into a few basic categories. Many mix more than one lighting strategy within a single fixture. All luminaires can be categorized as either direct lights, downlights, accent lights, or indirect lights. Many luminaires combine two or more of these strategies. For example, many dining room chandeliers include a downlight that provides accent or task lighting to the table top in addition to the fixture’s ambient lighting. Common fixture types and placement are covered below.

Catalog of Types of Direct Lights

These include most surface-mounted fixtures on walls and ceilings, often with a diffusing globe or lens to reduce glare.

In general, these are very efficient sources of light, but may also produce a lot of glare.

Common types include surface-mounted ceiling fixtures, pendants, chandeliers, and sconces.

Surface-mounted ceiling lights. Either incandescent or fluorescent fixtures mounted directly on the ceiling are a very efficient source for ambient lighting. Some, such as fluorescent “clouds,” use rounded diffusers that cast light on the ceiling as well as downward.
Pendant ceiling lights. Pendant fixtures are often used to provide task lighting above kitchen tables or eating counters and may also project light sideways and upward to the ceiling. Select a fixture at least 12 inches less in diameter than the table’s smallest dimension and mount the fixture 27 to 36 inches above the table or counter (see Figure 5-24 above). Mini-pendants with halogen spots are often used to accent breakfast bars and kitchen islands.
Chandeliers. When used over dining room tables, select a fixture at least 12 inches less than the width of the table and locate them 27 to 36 inches above the table, as in Figure 5-24 above). Some fixtures contain a central downlight to provide task lighting to the table.
Sconces. Wall sconces provide soft lighting in living and dining areas and hallways. Most provide some direct lighting as well as an indirect “wash” of light upward onto walls and ceilings. Often placed in pairs, they are typically located about 66 inches from the floor to the center of the sconce (Figure 5-25 shown below). Our photo of wall sconces is from the dinner theatre at Taliesin West - D Friedman.

Wall Sconces at Taliesin West, Scottsdale AZ (C) Daniel Friedman

What are Downlights & How are they Used?

These are predominantly recessed ceiling lights that create a dramatic effect by casting pools of bright light on floors and work surfaces while leaving the ceiling in shadow.

Used with A lamps, floods, or compact fluorescents, and spaced properly, downlights can create even general lighting. With more focused spot bulbs and special trims, they can function as task lighting, accent lighting, or wall washers.

What are Accent Lights?

When lighting a picture or single object, use a directional spot lamp in a shielded fixture.

These are often track-mounted or adjustable recessed fixtures, such as “eyeballs.”

Our photo (left - DJF) shows how Frank Lloyd Wright used accent lights in the corners of "the bunker" at Taliesin West as part of a compendium of different lighting methods all demonstrated in this space: direct, indirect, accent, and track lighting all are installed and create different effects in this structure that has no exterior windows (and was originally used for storage).

To create even lighting over a large picture or group of pictures, it is best to use special “wallwasher” fixtures, or nondirectional lamps such as A-bulbs or compact fluorescents (Figure 5-23 below)

What are Indirect Lights & how is Indirect Lighting Best Used?

Bouncing light off light-colored walls and ceilings creates a soft and diffused illumination with little glare and gives a room a feeling of spaciousness.

Examples include upward directed floor lamps and wall sconces, as well as site-built coves and valences, which can make use of cost-effective fluorescent tubes.

Coves reflect light off the upper walls and ceiling and dramatize a high or cathedral ceiling. Brackets provide downlighting as well to emphasize wall surfaces or artwork.

Typical cove and bracket details are shown in Figure 5-26 (above) and Figure 5-27 (below).

The shield should be designed to protect the bulbs from view within the room.

Best Uses of Recessed and Track Lighting

Recessed lighting can provide either ambient, task, or accent lighting, depending on the lamp type, its beam spread, and the type of reflector and trim used. Where recessed fixtures are used for ambient lighting, they should be spaced to provide even lighting without dark spots.

Track lighting follows the same design principles as recessed, but is best used for accent or task lighting in certain situations. It is particularly well-suited to situations where flexibility is required since fixtures may be easily moved as lighting needs change.

Guide to Lamps (Bulbs) Used with Recessed & Track Lights

Also see Guide to Recessed & Track Light Bulbs

Beam spreads for directional lights vary depending on the lamp and fixture. For general lighting, choose a wide flood with a beam spread of at least 50 degrees. BR lamps are the most economical directional lamp and provide good enough beam control for general lighting. Standard A lamps with Alzak trim or compact fluorescents also provide good general lighting.

Halogen PAR lamps offer more precise beam control suitable for task or accent lighting. Low-voltage M-16 and PAR36 lamps offer very precise beam control, making them well-suited to accent lighting. Because of their narrow focus, spots produce higher illumination levels than floods but over a smaller area. Beam spreads and lighting levels for common directional lamps are shown in Table 5-24.

Table 5-24: Performance of Common Directional Lamps (bulbs) (C) J Wiley, S Bliss

Guide to Recessed Light Housings

Typical residential recessed lights come in 4- to 7-inch diameters and can take a variety of different trims that significantly affect light output and glare.

For general lighting, a 5- to 7-inch diameter housing is commonly used. For accent lights, smaller 4-inch housings are available for both line-voltage and low-voltage figures. Special recessed housings are also available for compact fluorescents, sloped ceilings, and retrofit installations.

Standard recessed housings must be left uninsulated above. For insulated ceilings, use a can rated IC for “insulation contact.” Also make sure the housing is rated “airtight,” which is not true of all IC units. Air leaks through recessed lights can be a significant source of heat loss and moisture problems in cathedral ceilings.

Recessed Lighting Fixture Trims

The common black or white step baffles are designed for use with a PAR or BR lamp, although homeowners often put in the less expensive A19 bulbs.

Baffles reduce glare, but also cut light output by 50% or more for A lamps and up to 40% for directional lamps. Black baffles cut light output significantly more than white (Figure 5-28).

For maximum light output from a recessed lighting fixture, use a clear or gold specular reflector, also known as Alzak trim.

To reduce glare, which can be a problem with these highly efficient reflectors, it is best to use a deep-profile Alzak trim, offered by most recessed lighting manufacturers.

These work well with standard A19 bulbs as well as BR lamps (Figure 5-29). Gold Alzak is about 10% less efficient than the clear style.

For accent lighting, eyeballs and similar adjustable trims allow the homeowner to direct the light to the artwork or architectural feature being lit (Figure 5-30).

These are typically used with a narrow spot to provide bright focused light on a small area. Slotted wall wash trim is used to splash diffused light on broad areas of wall or bookcases. Nondirectional A lamps or compact fluorescents work well in this application. General recommendations for recessed lighting bulb wattage or bulb type and fixtrure spacing are given in Table 5-25.

Table 5-25: Recessed Lighting Recommendations: Bulb Sizes, Fixture Spacing (C) J Wiley, S Bliss

Spacing Guidelines for Light Fixtures

Also see Light Fixture Spacing

The general rule for ambient or task lighting is to space recessed ceiling fixtures approximately the same distance apart as the beam spread at the work height, typically assumed to be 30 inches above the floor (36 inches for kitchen counters). The beam spread is the central cone of light, where the beam is at least 50% of the brightness at the center of the beam.

Most manufacturers publish beam spread data for their recessed lights with different trim options. Beam spreads and lighting levels for some common fixtures and lamps are shown in Table 5-26.

Table 5-26.

For ambient lighting, choose a compact fluorescent, A lamp, or wide flood with a beam angle of at least 50 degrees. Typical spacing for ambient lighting with recessed lights is 6 to 7 1/2 feet for an 8-foot ceiling, or 7 to 8 1/2 feet for a 9-foot ceiling. Spacing from the first row of lights to the wall is half this distance.

For accent lighting, space recessed or track fixtures so their light hits the wall at about 30 degrees. For lighting a large wall area, the distance between fixtures should be equal to or less than their distance from the wall (see Figure 5-23).

Figure 5-23

Closet Lighting Selection & Installation - Fire Safety Clearances

Also see Closet Lighting Fire Safety

Due to risk of fire, the International Building Code and the National Electrical Code require that all fixtures installed in closets must be either surface-mounted or recessed and must completely enclose the bulb. Only incandescent or fluorescent lamps are allowed.

In addition, the fixture must be installed either in the wall above the door or on the ceiling and have the following clearances:

For surface-mounted incandescent fixtures: 12 inches to the nearest point of clothing or storage space.
For surface-mounted fluorescent fixtures: 6 inches to the nearest point of clothing or storage space.
For recessed fluorescent or incandescent fixtures (with a completely enclosed lamp): 6 inches to the nearest point of clothing or storage space.

Kitchen Lighting Requirements

Also see   Kitchen Lighting Requirements
  Ambient Kitchen Lighting Specifications
  Kitchen Lighting Counters, Sinks, Cooktops
  Table Top Lighting Specifications

Kitchens require general ambient lighting as well as task lighting on sinks, ranges, counters, and eating areas. Given the high lighting needs of a kitchen, the energy savings from fluorescent lights can be substantial. Look for fluorescent bulbs with a CRI over 80 and a color temperature near 2800K to match standard incandescent lights, or 3500K to match halogen lights.

Ambient Kitchen Lighting Specifications

For efficient general lighting, use one or more enclosed ceiling fixtures with a white diffuser that illuminates the ceiling as well as the space below. In a very small kitchen, placing the ceiling fixture near the sink and counter can provide effective task lighting as well.

For a softer glow in a kitchen, indirect lighting can also work nicely with lights placed in coves and above the cabinets to illuminate the ceiling.

Although not the most energy-efficient, recessed lighting has become a popular choice for kitchen lighting because of its sleek appearance and dramatic effect. For even lighting, use fixtures and lamps with wide beam spreads and spacing based on a 36-inch work plane (Figure 5-23). Also see the discussion on “Spacing,” page 202.

Figure 5-23

As a rough guide, the American Lighting Association suggests the following minimum lighting levels:

Small kitchens of under 75 square feet: 150 watts of direct incandescent lighting from up to three bulbs, or about 60 watts of fluorescent.
Kitchens up to 125 square feet: 200 watts of incandescent from up to four bulbs, or about 80 watts of fluorescent.
Kitchens over 120 square feet: two watts of incandescent lighting or 34 watt of fluorescent per square foot of floor area.

These numbers should be increased by 50 to 100% for indirect lighting, dark surfaces, lighting placed high in cathedral ceilings, or use of recessed lights with diffusers, baffles, or other light blocking trim.

Kitchen Task Lighting Guidelines for Counters, Sinks, Cooktops

Work counters, sinks, and cooktops all need high lighting levels. Where wall cabinets are present, under cabinet lighting provides excellent illumination for counters. Place lights as close as possible to the front of the cabinets to avoid glare reflecting off the work surface (Figure 5-23 shown above).

Low-voltage xenon “festoon” lamps provide bright, even light similar to halogen but without the high temperatures and pressures, eliminating the safety concerns associated with halogen. Also, xenon lamps can be touched with bare skin and provide 10,000 hours of service.

An alternative for lighting at counters is to place a row of recessed fixtures directly over the outer edge of the counter. If used for task lighting, place fixtures about 36 inches apart for 8-foot ceilings or 48 inches apart for 10-foot ceilings (see Task Lighting in Table 5-25).

Table 5-25: Recommendations for Recessed Lights (Ceiling Lights or "Pot Lights" (C) J Wiley, S Bliss

Sinks, cooktops, islands, and counters without cabinets above can be lit by small recessed downlights or track lighting. Mini-pendants with 12-volt halogen bulbs offer an attractive and functional way to illuminate islands, peninsulas, and eating counters (Figure 5-23).

Table Top Lighting Specifications

Choose a pendant at least 12 inches less in diameter than the table’s smallest dimension and mount the fixture 27 to 36 inches above the table.

A 120-watt incandescent or 40- to 50-watt fluorescent fixture will generally provide sufficient illumination (see Figure 5-24).

Bathroom Lighting Guidelines

Also see Bathroom Lighting Guidelines

Bathroom Mirror Lighting Recommendations

Good lighting is critical at the bathroom mirror for shaving, makeup, and other tasks of personal hygiene. For optimal lighting, place strip lights or globe type light bars at least 16 inches long on each side of the mirror centered at 61 to 64 inches (about the average eye height). Wall sconces on either side are also an option for smaller mirrors. These provide even cross lighting without shadows or glare (see Figure 5-23).

Figure 5-23

For small mirrors under 30 inches wide, use about 75 watts of incandescent lighting or 20 watts of warm-white fluorescent on each side. For larger mirrors, use up to 150 watts of incandescent or 40 watts of fluorescent on each side. Additional lights across the top of larger mirrors are also helpful. If using fluorescents, select lamps with high CRIs and warm color temperatures in the 2700K to 3000K range.

Lighting from above the mirror only using globe-type light bars, a pair of recessed downlights, or a lighting soffit is acceptable as long as the vanity top is a light color. Otherwise, areas under the eyes, nose, and chin will be in shadow. If recessed fixtures are used, choose an A lamp, flood, or compact fluorescent for a diffused beam.

General Lighting. As a rule of thumb, provide one watt of incandescent or 1/3 to 1/2 watt of fluorescent light per square foot of floor space. Increase this by 50 to 100% for recessed lights, indirect lighting, or a room with dark surfaces. In a small bathroom, the mirror lights can also provide the ambient light.

For larger baths, a separate ceiling fixture mounted near the tub and toilet can be useful for ambient light and reading. Finally, in a room with a high ceiling, indirect lighting with coves or uplights can create a feeling of spaciousness in a bathroom, along with a pleasing, soft glow.

Guidelines for Lighting Over Tub and Shower

A recessed light with a white diffuser mounted over the tub or shower will be appreciated by bathers. Electrical codes require that these fixtures be totally enclosed and rated for use in a damp location (tub area) or wet location (shower). Most require GFCI protection for their UL rating. In addition, fixtures must be at least 6 feet above the water line and switches must be a minimum of 5 feet from the edge of the bathtub or shower.

Watch out: Check with local code officials in your own jurisdiction for specific lighting and electrical safety requirements.

-- Adapted with permission from Best Practices Guide to Residential Construction.

Resources: Manufacturers, Industry Associations, & Sources of Indoor Wall Materials, Flooring, Carpeting, Lighting, Sound Control Materials

Industry & Trade Associations for Lighting and Other Interior Components in buildings

American Lighting Association www.americanlightingassoc.com

Association of the Wall and Ceiling Industries www.awci.org

Carpet and Rug Institute (CRI) www.carpet-rug.org

Drywall Finishing Council www.dwfc.org

Forest Stewardship Program www.fscus.org

FloorFacts www.floorfacts.com

The Gypsum Association www.gypsum.org

National Oak Flooring Manufacturers Association (NOFMA) www.nofma.com

National Wood Flooring Association www.woodfloors.org

Painting and Decorating Contractors of America www.pdca.org Smartwood/Rainforest Alliance www.smartwood.org

-- Adapted with permission from Best Practices Guide to Residential Construction.

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Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.

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The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop, and from the InspectAPedia bookstore. The 2010 edition of the Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ^®^{author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.}

Recommended books on electrical inspection, electrical wiring, electrical problem diagnosis, and electrical repair can be found in the Electrical Books section of the InspectAPedia Bookstore. (courtesy of Amazon.com)
* Safety Hazards and Safe Inspection Procedures for Electrical and Home Inspectors at Residential Electric Panels
Aluminum Wiring Information Website Aluminum Electrical Wiring Hazards and Repairs: in-depth authoritative info, photos, documents including selection of proper vs. ineffective repair methods. E.g.: Ideal 65 "Twister" purple connector fails in field and lab testing with aluminum wire.
Ampacity of an Electrical Service: How to determine the electrical service size or ampacity entering a building
Circuit Breaker, a bad one fails to trip failure at aluminum bus-to-circuit breaker connection - field report and photographs
Electrical Panels, How to Inspect in buildings, safety for electrical inspectors, electrical panel, fusing, wiring defects, defective products. Inspection Class Presentation
Federal Pacific Electric (FPE) Stab-Lok Circuit Breaker Panel Hazards Website - Latent fire hazards, in-depth authoritative research, documents, advice on Stab-Lok electric panel and circuit breaker failures and what to do when this equipment is found in buildings.
Lightning Strike Risk Assessment, Protection Systems & Services
Multi-wire branch circuit inspection and defects
Rust and Corrosion in Electrical Panels, A Study and Report on Frequency and Cause for Electrical and Home Inspectors at Residential Electric Panels
"Electrical System Inspection Basics," Richard C. Wolcott, ASHI 8th Annual Education Conference, Boston 1985.
Safety Hazards and Safe Inspection Procedures for Electrical and Home Inspectors at Residential Electric Panels
"Simplified Electrical Wiring," Sears, Roebuck and Co., 15705 (F5428) Rev. 4-77 1977 [Lots of sketches of older-type service panels.]
"How to plan and install electric wiring for homes, farms, garages, shops," Montgomery Ward Co., 83-850.
"Electrical System Inspection Basics," Richard C. Wolcott, ASHI 8th Annual Education Conference, Boston 1985.
"Simplified Electrical Wiring," Sears, Roebuck and Co., 15705 (F5428) Rev. 4-77 1977 [Lots of sketches of older-type service panels.]
"How to plan and install electric wiring for homes, farms, garages, shops," Montgomery Ward Co., 83-850.
"Home Wiring Inspection," Roswell W. Ard, Rodale's New Shelter, July/August, 1985 p. 35-40.
"Evaluating Wiring in Older Minnesota Homes," Agricultural Extension Service, University of Minnesota, St. Paul, Minnesota 55108.
"Electrical Systems," A Training Manual for Home Inspectors, Alfred L. Alk, American Society of Home Inspectors (ASHI), 1987, available from ASHI. [DF NOTE: I do NOT recommend this obsolete publication, though it was cited in the original Journal article as it contains unsafe inaccuracies]
"Basic Housing Inspection," US DHEW, S352.75 U48, p.144, out of print, but is available in most state libraries.
Electrical System & Wiring Hazard Inspection, Detection, Cause, Remedy, Prevention - Main Electrical Page
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Bathroom Lighting Guidelines

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Resources: Manufacturers, Industry Associations, & Sources of Indoor Wall Materials, Flooring, Carpeting, Lighting, Sound Control Materials

Industry & Trade Associations for Lighting and Other Interior Components in buildings

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