The insulators made of glass were initially used to protect homes against lightening. Insulators of glass and pottery are used on telegraph and telephone poles since 1844. The early insulators were non-threaded and had designs of ram’s horn and glass blocks. Porcelain and ceramic insulators became popular in the late 19th century. Insulators were made in different shapes. The popular pieces include “Mickey Mouse”, “Gingerbread Man” and “T-Bar.”