Abstract: An electrically powered submersible pump system has a pipe stack in which a dielectric oil is circulated within tubular electric power supply conductors, for which the oil provides insulation, down to the pump head to cool and lubricate the motor bearings. The oil is returned between the conductors and a surrounding cofferdam pipe. The liquid being pumped is guided in a duct between the cofferdam pipe and an outer load bearing pipe. The pipe stack is divisible into sections of convenient length, the conductors, the cofferdam pipe, and the outer pipe having releasable connector means at each end of each pipe stack section.