Light bulbs come in a variety of shapes and sizes as well as wattage amounts. Light bulbs can be categorized by the shape of their bases (the part of the bulb that screws into a light socket), and the letter E before a number indicates the bulb's base type. E12 designates a particular type of light bulb base designed for specific types of lighting.

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An image of a lightbulb.

Light Bulb Bases

According to Harrington Lights, there are seven types of light bulb bases: E10, E11, E12, E14, E17, E26 and E39. Each base size fits a specific light socket or style of lighting fixture. E12 light bulbs are generally known as candelabra light bulbs.

E12 Size

An E12 bulb's base is 12 millimeter in diameter and, as such, will only fit light sockets that are the same size. The average bulb is quite short at just under two inches in height. The typical bulb is identifiable by its unique teardrop shape, bulging out slightly in the center before narrowing at the tip.

E12 Bulb Uses

E12 light bulbs are commonly used with hanging chandeliers and small night lights. They can also be found in electric candles. E12 bulbs can be used in any lighting appliance that has a matching 12 millimeter diameter socket.

E12 Bulb Anatomy

E12 incandescent light bulbs contain a delicate tungsten-based wire in the center that, when heated by electrical current, produces light. The glass of the bulb seals out air infiltration which would cause the filament to burn out prematurely.

Safety Tips

The E12 bulb will only fit into a candelabra-size socket. The bulb must be rotated carefully into its base; forcing the bulb into place can damage the bulb or light fixture, and may even lead to injury or fire. Bulbs can become hot to the touch very quickly, so it is important to allow the bulb to cool down before touching or replacing a light bulb.