What are elec. insulators?

Electrical insulators, also sometimes called “dielectrics,” are materials that can withstand and absorb the flow of electric current, and are commonly used to seal or protect electrical wires. Wires and other electrical conductors are usually very powerful in terms of the charges they emit. Unless they are insulated, there is a risk that people could receive an electric shock by touching or even working closely with them, and they also present an increased risk of fire when enclosed within wooden or other flammable materials. An insulator basically protects and shields the conductor so that electricity can flow through the conductor, not out of it. Insulators are common in construction, industry, and mechanical applications, virtually anywhere there is an electric current that needs shielding. They can be made of many things. Glass and porcelain were some of the earliest designs and these materials are still popular in some circles. More commonly, though, modern conductors are coated with silicone resins or other plastic-like materials designed specifically for electrical purposes.

Basic composition

Dielectric materials consist of substances with electrons, or energetic particles, that are compressed together by chemical processes. It is nearly impossible to pass electrical voltage through these materials. Some insulators are thought to have higher thresholds for electrical voltage than others and, as a class, are usually referred to as “high voltage insulators”. These types of insulators are really important for things like transformers or big circuits in power plants. They’re probably more powerful than someone would need to line a home electrical system or a series of wires in an appliance, but they’d work in most cases. The main idea here is to coat the wire or other “live” element to keep the current, whether weak or strong, contained.

The first models

Glass was commonly used as an electrical insulator in the early days of electricity. Technicians discovered quite quickly that live wires were a hazard, and glass was one of the most readily available substances capable of containing charges. It was usually formed into tubes of various diameters that would slip over wires and other electrical items. In the 1800s, this material helped protect exposed telegraph wiring.

Along with other non-metallic materials such as porcelain, mica and ceramics, glass can withstand the highest volts of electric current. Rubber was invented in the mid-1800s and was initially used to help seal glass insulators and to give them a tighter, snug fit along the wires. Rubber has a lower voltage threshold than glass and porcelain due to its composition of loose electrons, which made it less suitable for use on its own. Combined with glass or porcelain, however, the result tended to be very strong.

Modern advances
Electricians today are often able to achieve a much tighter, more custom fit with the use of Teflon® and silicon dioxide sleeves. These materials are highly malleable which means they can be made to actually coat wires and conductors with very little space on either side. As they have become more common, they have also become less expensive. Sleeving moves with the wires in most cases and can be very useful when it comes to protecting power lines and internal wiring inside transformers and generators.

Composite insulators
There are also composite insulators made from a combination of different materials. Sometimes they use something like glass in one place but Teflon® in another, but they could also be made with entirely proprietary blends or combinations of materials. Composite insulators are suitable for a variety of electrical engineering purposes, ranging from automobiles to household appliances. They tend to lack the strength glass and porcelain must have to withstand high electrical voltage and can wear out faster, but are ideal for large-scale manufacturing applications due to their low cost and versatility.

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