This part of IEC 61892 is applicable to system design of electrical installations and equipment in mobile and fixed offshore units including pipeline, pumping or 'pigging' stations, compressor stations and single buoy moorings, used in the offshore petroleum industry for drilling, production, accommodation, processing, storage and offloading purposes. It applies to all installations, whether permanent, temporary, transportable or hand-held, to AC installations and DC installations without any voltage level limitation. Referenced equipment standards may give voltage level limitations. This document specifies requirements such as those of: – sources of electrical power for manned and unmanned units; – system earthing, both for low voltage and high voltage installations; – interface for electric transmission systems with power supplied from shore, between interconnected offshore units, and with power supplied by offshore units to subsea installations; – distribution systems; – cables and wiring systems; – system studies and calculations; – protection against electrical faults; – lighting; – energy control, monitoring and alarm systems; – turret/swivel;