Single-core underground power cables can induce voltages and currents in their metallic sheaths. The sheath induced currents are undesirable and generate power losses and reduce the cable ampacity whereas the induced voltages can generate electric shocks to the workers that keep the power line. This means that it is very important to know the values of sheath currents and induced voltages and the factors affecting them.So this bbbkdiscussed the following: - Calculations of the induced voltages in single-core cables with various voltages levels from 11 kV to 500 kV with briefly studying the factors affecting them. - Studying the factors affecting the sheath losses in single-core cables by calculating the sheath currents (eddy-circulating) and their sheath losses in single-core cables with various metallic sheath materials with taking into consideration the following factors: Types of sheath bonding methods (single-point bonding, two-points bonding, cross bonding) and cable layouts(trefoil, flat), cable parameters, cable spacing, sheath resistance, phase rotation, conductor current, power frequency, the minor section length in cross bonding.