Light Fixture Bases

Incandescent Bases

• Incandescent bulbs come with the familiar screw-in type of bases. The most common base is called a medium or an Edison base, and this is the standard base that fits into most lighting and lamps. Variations on this are candelabra, which is a smaller type of Edison base, a mogul base, which is a larger type of Edison base and oddities like a three contact medium, a three contact mogul and an intermediate. The odd base types will fit specialized applications like sewing machines or in-ground pool lighting.

Halogen Pins

• Pins that jut out from the bottom of a ceramic based bulb generally belong to the halogen light class. These pins are designed to push into and be pulled out of a spring loaded catch. These types of halogen bulbs are made for specialized lighting applications like track lighting and portable lighting. Some of the newer lights with pins are the energy efficient LED lighting that can be used in the same applications but will offer greater energy savings.

Fluorescent Pins

• The common long fluorescent tubes have light fixture bases with a dual pin design. The pins are located on the ends of the tube and are usually pushed and turned into a spring-loaded holder. Although certain fluorescent tubes may also be fitted with a single pin or a recessed pin, the most common types feature the standard dual pin arrangement.

Pins and Pegs

• Compact fluorescent lights feature a center square or rectangular peg surrounded by dual or quadruple pins. These types push into a specialty socket and pull out when they need to be changed. Although once common, they are being replaced by standard medium and mogul screw in fixture bases, but on older light fixtures, the pin and peg arrangement for compact fluorescent bulbs is still prevalent.

Recessed End Contacts

• Industrial halogen lights or portable workshop halogen lights feature recessed end contacts. These long and narrow glass bulbs fit into a rectangular fixture and are common lighting for portable working applications. The base on each end is pressed against spring loaded clips in the fixture, and the spring tension of these clips holds the bulb firmly in place. These specialty bulbs put out large amounts of brilliance but they also become very hot and need to be handled with care when changed.