Types of Light Bulb Bases

We think of a bulb-shaped glass lamp with a filament that screws into a chandelier or table light as a light bulb. In fact, there are dozens of shapes, sizes and base types for these illuminating objects.

Identification

All lamps require connection to a power source to "incandesce" or "fluoresce." The base seals the lamp and houses the electrical contacts to make a connection with the contacts in the fixture.

History

Experimental electric lamps built in the 19th century used carbon filaments and bi-pin bases that were simply two contacts sealed in glass.

Function

Lamp bases correspond to type and use of the light; the most familiar types of bases are screw and bi-pin because they fit common household fixtures. Specialty fixtures for commercial, theatrical or medical use may use four-pin, blade or pre-focus bases.

Size

The most familiar base sizes are miniature, candelabra and standard or medium: specialty fixtures may require midget, intermediate or miniature sized bases, large commercial and theatrical fixtures take mogul-sized bases.

Considerations

Dozens of non-standard base types are used for electronics and new technologies.

Fun Fact

Thomas Edison's first light bulb used a bamboo instead of carbon filament and a spiral-ridged base that would become known as the "Edison base."

Resources

• Reproduction light bulbs