Glass insulators were first produced in the 1850′s for use with telegraph lines. As technology developed insulators were needed for telephone lines, electric power lines, and other applications. In the mid 1960′s a few people began collecting these antique glass insulators. Today there are over 3,000 insulator collectors. Insulator clubs, local and national shows, and good reference books are available.
A true insulator is a material that does not respond to an electric field and completely resists the flow of electric charge. In practice, however, perfect insulators do not exist. Therefore, dielectric materials with high dielectric constants are considered insulators. In insulating materials valence electrons are tightly bonded to their atoms. These materials are used in electrical equipment as insulators orinsulation. Their function is to support or separate electrical conductors without allowing current through themselves. The term also refers to insulating supports that attach electric power transmission wires to utility poles or pylons.
Some materials such as glass, paper or Teflon are very good electrical insulators. Even though they may have lower bulk resistivity, a much larger class of materials are still “good enough” to insulate electrical wiring and cables. Examples include rubber-like polymers and most plastics. Such materials can serve as practical and safe insulators for low to moderate voltages (hundreds, or even thousands, of volts).
Insulator (electricity), http://en.wikipedia.org/w/index.php?title=Insulator_(electricity)&oldid=471160982 (last visited Jan. 19, 2012).




