What are the socket sizes used for traditional home lighting in the USA?
• E27: A conventional pear shaped incandescent bulb uses an E27 socket base. The 27 means the socket diameter is 27 mm. This socket size has also been called a medium socket. Traditional indoor table lamps, ceiling fixtures, and bathroom fixtures use the E27 socket type. Recessed lighting fixtures typically found in the basement and kitchen also use the E27 socket type; however bulbs for recessed lighting are typically described as PAR20, PAR30, and PAR38. Outdoor flood lights and some porch lights also use the E27 base. These bulbs are 110v. • E12: Most chandelier fixtures in the USA require use the E12 socket base. The diameter of this socket is 12 mm. Also many porch light fixtures use the E12 socket base. These bulbs are 110v. • GU10: The GU10 lamp is normally used for small track lights that have traditionally used 25w and 40w halogen lamps. The distance between the center of the pins on the bottom of the lamp are 10 mm. These bulbs are 110v. The pin has a head on the end. • MR16:
