Asbestos in Circuit Breakers

Circuit breakers are designed to prevent electrical fires, but many mid twentieth century breakers were built with materials that contained asbestos. The mineral was used to insulate, strengthen, and protect components exposed to heat and electrical arcs. As these breakers aged or were serviced, workers could be exposed to asbestos fibers that were hidden inside the equipment.

Why Asbestos Appeared in Circuit Breakers

Electrical systems generate heat, and circuit breakers must withstand high temperatures when they interrupt a surge or arc. Manufacturers added asbestos to breaker components because it provided:

• Heat resistance
• Electrical insulation
• Mechanical strength
• Fire protection

Breakers that handled high voltage loads often relied on asbestos containing parts for safety and durability.

Common Breaker Components That Contained Asbestos

Asbestos appeared in several internal parts, including:

• Arc chutes
• Insulating boards
• Molded phenolic resin housings
• Contact barriers
• Gaskets and seals
• Switch bases
• Internal wiring insulation

Arc chutes were one of the most common asbestos components. They were designed to channel and cool electrical arcs during operation, and many were built from asbestos reinforced materials.

How Exposure Occurred

Exposure risks increased when breakers were installed, repaired, or dismantled. Activities that created exposure included:

• Opening breaker housings
• Cleaning or replacing arc chutes
• Drilling or cutting phenolic panels
• Scraping gaskets and insulation
• Handling aged or brittle components
• Removing breakers during electrical upgrades

Electricians working in tight mechanical rooms or electrical vaults faced significant risks if dust was released during service.

Industrial, Commercial, and Military Use

Asbestos containing breakers were used in:

• Factories and refineries
• Power plants
• Shipyards
• Commercial buildings
• Schools and universities
• Military bases and naval vessels

Large industrial facilities often had banks of high voltage breakers that required routine inspection and maintenance. These breakers remained in service for decades, long after safer materials became available.

Who Faced the Greatest Risk

The people most likely to be exposed included:

• Electricians
• Power plant workers
• Shipyard workers
• Maintenance technicians
• Building engineers
• Recycling and demolition crews

Some electricians serviced breaker panels daily, creating repeated opportunities for exposure.

Health Risks Linked to Electrical Equipment

Asbestos exposure can cause long term illnesses, including:

• Mesothelioma
• Lung cancer
• Asbestosis
• Pleural scarring

Because symptoms often appear many years later, workers who handled breakers in the 1960s through the 1990s may only now be experiencing health effects.

Why It Still Matters Today

Many older buildings still contain original breaker panels and electrical equipment. Some arc chutes and insulating boards remain in service because the components appear intact, even though their materials may have deteriorated internally.

Electricians who work on historic or aging electrical systems should be aware that older circuit breakers may contain asbestos. Testing components before disturbing them can prevent accidental exposure.

Asbestos in circuit breakers shows how deeply the material was embedded in electrical systems. Recognizing these hidden hazards helps protect workers who maintain or replace aging infrastructure today.