Electricity: Lighting Basics

Indirect lights shine down from behind valance; Floor fixture casts dramatic light up through the branches of a plant

Good lighting can do wonders. It can accentuate or soften colors, create a festive or soothing mood, call attention to objects you want to show off and provide safe work areas and snug places to read.

Residential lighting falls into three categories: general, accent and task. General lighting, usually from ceiling or wall fixtures, radiates light throughout a room, as sunlight does. Task lighting focuses on individual areas and may come from portable lamps, under-cabinet fixtures, track lights or recessed spotlights. Accent lighting is more decorative and may be in the form of halogen lights focused on artwork or spot lights accenting architectural details.

How Much Light Is Enough?

Opinions vary on the right amount of light needed for a room; so much depends on personal preference, type of light, color of room and activities performed there. But there are a few rules of thumb:

  • Kitchens, laundry rooms and workshops. 3 to 5 watts of incandescent light per square foot (32 to 54 watts / sq. meter) of floor.
  • Living rooms, dens and bedrooms. 1 to 2 watts of incandescent light per sq. ft. (11 to 22 watts / sq. meter.)
  • Bathrooms. 6 watts per sq. ft. (66 watts / sq. m), with vanities receiving 30 to 40 watts per running foot (30 cm) of vanity top.

Note: When installing fluorescent light, divide the number of watts above by about one-third.


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Beam Spreads of Bulbs

Reflector-type spotlights cast a narrow beam of light (about 200 angle), which is good for task or accent lighting.

Standard incandescent bulbs , unlike reflector-type bulbs, cast light very broadly in all directions.

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Reflector-type floodlights cast a wide beam of light (about 70° angle), which is good for general lighting.

How Distance Affects Light Levels

A bulb’s capacity to light a surface is dramatically affected by distance. A standard light bulb mistakenly placed in a recessed or track fixture will only provide a fraction of the light that a reflector bulb would provide. If 100% of the light from a bulb reaches a surface 1 ft. (30 cm) below it, only one-fourth of that light hits the surface if the bulb is raised to 2 ft. (60 cm) above the surface, one-ninth at 3 ft. (90 cm) and a mere one-sixteenth at 4 ft. (120 cm) When you need bright task lighting, keep the light close to the work surface, use a bulb that focuses more light and has wattage near the fixture’s maximum.

Be sure to use the proper type and rating of bulbs in your fixtures. For fire safety, never exceed ratings listed on a fixture.

Last modified: Friday, 2020-02-28 15:20 PST