Professional Answer: Soil thermal resistivity is one of the most critical factors for underground cable installations. It measures the soil's ability to resist the flow of heat. A high thermal resistivity means the soil is a poor conductor of heat, trapping the heat generated by the cable and causing its temperature to rise. This requires the cable's ampacity to be "derated," or lowered, to prevent overheating. Conversely, soil with low thermal resistivity (e.g., wet clay) allows for better heat dissipation, permitting a higher current load. Our company offers a range of tools and equipment to prepare trenches and manage backfill materials, ensuring optimal thermal environments for your buried cables.