Reefer Plug

A reefer plug (also called a reefer socket or reefer power point) is an electrical outlet built into a container ship's hold structure or deck fittings to supply three-phase power to a refrigerated container's integral refrigeration unit. Each plug position has a defined power rating—typically 380–460 V, 50 or 60 Hz, three-phase—and connects to the vessel's power management system, which must allocate sufficient electrical load capacity for the number of reefer containers embarked. The total reefer plug capacity of a vessel determines the maximum number of refrigerated containers that can be carried simultaneously. The chief mate accounts for reefer plug requirements during the loading plan, ensuring that all reefer containers are assigned to powered slots and that the electrical load does not exceed the auxiliary engine capacity. The OOW on watch monitors reefer alarms displayed on the cargo control panel or the reefer monitoring system, logging any temperature excursion or power fault and alerting the chief mate. Reefer containers must be connected to power as quickly as possible after loading to avoid temperature excursion of chilled or frozen cargo. Port arrival procedures include confirming reefer connection to shore power if available, minimising fuel consumption from the vessel's own generators.