What does "Thermal system ACM" refer to?

"Thermal system ACM" refers to thermal insulating materials that are used in heating systems, which typically contain greater than 1% asbestos. Such materials include insulation on pipes, boilers, and ducts that are designed to regulate temperature and prevent heat loss. The presence of more than 1% asbestos is significant because it poses health risks during disturbance or degradation of those materials, leading to the release of harmful asbestos fibers into the air.

In the context of the other choices, they do not accurately reflect the definition of "thermal system ACM." Materials that are classified as containing asbestos but are below the 1% threshold are generally not considered hazardous under regulatory frameworks, which distinguishes them from the materials described in the correct answer. Additionally, options involving cold systems or electrical conduits do not fall under the thermal system category, as they pertain to different applications.