Thermal resistivity testing measures the capacity of the ground to conduct or dissipate heat. An accurate knowledge of the thermal properties of a soil (natural or made by man) is important for the plan and putting in place of underground pipelines and transmission cables. The thermal resistivity of a soil determines whether a buried power cable remains cool or overheats. Any heat produced by current flowing through an underground electricity power cable must be properly dissipated. A build-up of heat around the cable can reduce transmission efficiency, or in the worst cases cause the cable to melt.