Asbestos Electrical Panels and Wire Insulation

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From the earliest days of commercial electricity, manufacturers used asbestos in various components for electrical panels. The toxic mineral additive protected building tenants from fire and electrocution but also exposed electricians and other workers to severe health risks.

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The electricity for a building is received and distributed through a device called an electrical panel or distribution box. Electrical current produces heat, and if not grounded properly, it can arc and cause a fire or electrocution injury. In the early 1900s, as electricity became popular in the United States, manufacturers sought materials that could make electrical supply and distribution systems safer.

Years Produced

1930s – 1980s

Asbestos became a favored solution thanks to the fibrous mineral’s resistance to heat and electricity, low cost and the ease with which manufacturers could mix it into cement, millboard, plastic, cloth and paper. Though company executives knew of the harmful effects of inhaling asbestos dust as far back as the 1930s and 1940s, the link between asbestos exposure and diseases, such as asbestosis and mesothelioma, was not made public until decades later.

Electrical panel components manufactured with asbestos include:

Ebonized asbestos panel

Ebonized asbestos panels:

“Asbestos lumber” was a type of easily workable asbestos-containing cement marketed as a fireproof alternative to wood boards. “Ebonized” asbestos lumber was treated with a special compound to make it resistant to moisture as well.

Asbestos-cement electrical shielding

Asbestos-cement electrical shielding:

Simple sheets of asbestos cement could be placed in between electrical components as shielding, and asbestos cement could also be formed into arc chutes that completely enclose switch equipment.

Molded asbestos-cement bases

Molded asbestos-cement bases:

Manufacturers often shaped asbestos cement to fit specific electrical components, removing the need to install extra parts for shielding.

Asbestos electrical paper

Asbestos electrical paper:

Pieces of asbestos insulation paper, also known as flash guards, were used to line the inside of many electrical boxes. Asbestos paper products are highly vulnerable to wear and tear, creating a higher asbestos exposure risk.

Asbestos wire insulation

Asbestos wire insulation:

Asbestos was sometimes used to fireproof and insulate individual wires. Fraying wire insulation can easily release dangerous asbestos fibers.

Asbestos high voltage cable wrap

Asbestos cable wrap:

Like pipes, thick electrical cables were sometimes wrapped in asbestos paper or cloth, which can degrade and crumble over time.

Many electrical components were also made out of molded asbestos plastic. Mesothelioma Guide

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Quick Facts:
  • Places Used: Electrical supply systems for buildings and ships
  • Toxicity: Low
  • Asbestos Use Banned: No
  • Friable: No

In 1879, Thomas Edison unveiled the first electric bulb and his vision for the future of lighting. Many of his contemporaries also foresaw the huge market electrical technology would create and founded companies to meet this demand over the following decades.

George Westinghouse established Westinghouse Electric in 1886, which went on to build hundreds of power stations throughout the United States. In 1892, Edison’s own business merged with the Thomas-Houston Electric Company to form General Electric, which ensured his lasting legacy in the 20th century and beyond.

In 1902, the Detroit Fuse and Manufacturing Company began to manufacture electrical equipment, and by the time it produced its first power distribution panel in 1926, its trademark logo was so widely recognized the company had changed its name to “Square D” to match.

Each of these companies and numerous other competitors eventually came to use asbestos in electrical components. By the 1940s, when electricity had found its way into most American towns and cities, many businesses, such as the Johns Manville Corporation, had already made a fortune off asbestos-containing cement and thermal insulation, so it was just a short step further into the growing electrical insulation industry.

However, after successful personal injury lawsuits in the 1970s and 1980s revealed the deadly consequences of asbestos exposure, electrical panel manufacturers began to replace the asbestos in their products with substitutes such as gypsum, calcium silicate, expanded perlite, cellulose and polystyrene.

Popular asbestos-containing electrical panel and wire insulation brands include:
Manufacturer Brand

General Electric

Deltabeston wires

Johns Manville

Ebony electric board




Siemens Energy & Automation



Turner & Newall

Sindanyo asbestos board

Union Carbide Corporation

Bakelite Panels

Other manufacturers of these products include:

Dangers of Asbestos Electrical Panels and Wire Insulation

In factories that produced asbestos panel compounds, workers had to add raw asbestos fibers to tar, cement and millboard and other materials, creating high levels of toxic dust in the air. The amount of asbestos in mixtures varied. The finished products pose a threat to construction workers, electricians, homeowners and demolition crews, because sawing, drilling, sanding or breaking electrical panels can release asbestos fibers. Simply replacing a blown fuse on an older electrical supply system can put workers in contact with crumbling asbestos materials.

Exposed to an Asbestos Product?

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Microscopic asbestos dust has no scent, and it can easily contaminate workers’ clothing and lodge in people’s lungs permanently, causing cellular damage over time. Typical asbestos-abatement procedures require wetting dangerous areas to prevent fibers from becoming airborne, but this may not be an option with electrical systems.

To prevent electrical hazards from supply systems, abatement workers must either use a dry technique with High-Efficiency Particulate Air (HEPA) ventilation or ensure connectors are disconnected or shut off. Dry asbestos-abatement procedures require special approval from the Environmental Protection Agency.


Electricians and other tradesmen have filed hundreds of claims against asbestos electrical panel manufacturers after developing serious illnesses such as lung cancer and mesothelioma. Both Westinghouse and General Electric have lost many workers compensation cases based on occupational asbestos exposure, and victims have received compensation through personal injury lawsuits as well.

In 2003 for example, a San Francisco jury awarded almost $3 million to Philip Hoeffer, a retired electrician who had developed pleural mesothelioma. Hoeffer had been exposed to asbestos while installing, repairing and removing electrical panels during his U.S. Navy service and his civilian career. The defendant in the case was Rockwell Automation, the successor company to Allen Bradley, but the trial award represents only part of the compensation Hoeffer received, as the other companies in the lawsuit settled with him out of court.

In many cases, compensation is available through special trust funds for asbestos-related claims. Johns Manville set up the first asbestos personal injury settlement trust in 1988, setting a precedent in bankruptcy law many other former asbestos-industry companies have followed in the years since.

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Daniel King joined in 2017. He comes from a military family and attended high school on an Air Force base in Japan, so he feels a close connection to veterans, military families and the many hardships they face. As an investigative writer with interests in mesothelioma research and environmental issues, he seeks to educate others about the dangers of asbestos exposure to protect them from the deadly carcinogen. Daniel holds several certificates in health writing from the Centers for Disease Control and Prevention, and he is a member of the National Association of Science Writers.

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12 Cited Article Sources

The sources on all content featured in The Mesothelioma Center at include medical and scientific studies, peer-reviewed studies and other research documents from reputable organizations.

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Last Modified January 20, 2020

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