Lighting Research Center NYSERDA Lighting Patterns for Homes Image Map


Incandescent A-Lamp, Candelabra, and Globe

Incandescent bulbs offer significantly lower efficacy (the amount of light produced per unit of input power) and shorter life than fluorescent and LED bulbs. Restrict their use to applications where short hours of use are expected.

Incandescent bulbs are available in a variety of shapes and sizes. The letter designation refers to the shape, and the number indicates the maximum diameter of the bulb in eighths of an inch. For example, a bulb labeled "A19" is the shape most commonly found in homes, and is 19 eighths of an inch (2-3/8") in diameter at the widest point. Different base types are available; the most common is a medium screwbase. Decorative candelabra bulbs are often used in chandeliers. Globe bulbs (G-lamps) are spherical and typically are used where the bulb can be seen.

Frosted bulbs give a softer appearance that is often preferable in the home. Use bulbs with clear glass only when you want to see the filament (such as in a low-wattage decorative chandelier, or when sharp shadows are desired). If the filament is visible, the light will be very intense and the direct glare may be unacceptable.


  • Incandescent bulbs become very hot. Keep combustible materials away from the bulb and avoid touching while in use.


Example Patterns