SIZES: All sockets sizes are measured by the diameter of the threaded base of the bulb.
Candelabra sockets (E12) are for bulbs that are 12 mm (just under 1/2") in diameter.
Almost all of these are made of either phenolic resin or porcelain.
As the name implies, these are used mostly in candelabras. However,
many are are also used in small lamps & night lights.
Intermediate sockets (E17) are less commonly used and are for bulbs that are 17 mm
(just over 5/8") in diameter. They are used in some track lighting.
Medium sockets (E26), for bulb that are 26 mm (approximately 1") also called Edison sockets
these are the most common size used in table lamps. There are three main materials used in
Metal - there are two primary categories:
Plated aluminum or brass
Mogul sockets (E39) for bulbs that are 39 mm (approximately 1½") in diameter.
Their in-home use is generally limited to floor lamps.
This is a thermosetting plastic which was originally known as Bakelite.
The advantage of this type of plastic is that it will stand subtantially more heat than
thermoplastic resins, such as polyethylene or PVC.
Clay, silica and other ingredients are combined and fired to create a
material that is extremely heat resistant. These can be glazed or unglazed.
Aluminum with a brass colored (gilt) plating
Aluminum with a nickel plating OR
Solid brass with a lacquered finish
Solid brass with a nickel finish
Solid brass with an antique brass finish