Electrical insulator materials:
Pin type Insulators used for low-voltage power transmission are made from glass, porcelain or composite polymer materials. Porcelain pin insulator is made from clay, quartz or alumina and feldspar, and is covered with a smooth glaze to shed water.

Electrical insulator materials properties:
Porcelain pin Insulators made from porcelain rich in alumina are used where high mechanical strength is a criterion. Porcelain has a dielectric strength of about 4–10 kV/mm. Glass has a higher dielectric strength, but it attracts condensation and the thick irregular shapes needed for insulators are difficult to cast without internal strains. Much pin insulator manufacturer stopped making glass insulators in the late 1960s, switching to ceramic materials.

Electrical insulator materials trending:
Recently, some electric insulator utilities have begun converting to polymer composite materials for some types of insulators. These are typically composed of a central rod made of fibre reinforced plastic and an outer weathershed made of silicone rubber or ethylene propylene diene monomer rubber (EPDM). Composite insulators or composite pin type insulators are less costly, lighter in weight, and have excellent hydrophobic capability. This combination makes them ideal for service in polluted areas. However, these materials do not yet have the long-term proven service life of glass and porcelain.

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