Typical reefer containers cannot operate without being hooked into a power source. They typically supply electricity to the Cooling Unit through a generator attached to the container. These generators can run on fuel, electricity, or a combination of both.A reefer must be connected to a specialised electrical power outlet, typically of 32 amps and 380/440 volts, when it is being stored at a terminal. Terminals install reefer plugs, which are integrated into outlets feeding a corresponding number of reefers, in their yards to give power.