An incident on a German very high voltage network (Cf ARIA N°32455) caused disturbances in the power grid by generating a low frequency threshold causing several units in the refinery to switch over to the safety mode. In line with the architecture of the power supply system, only the units supplied by the utility turbo-alternators were operating. These included the utilities, the CLAUS 4 hydrogen sulphide conversion unit, SCOT tail gas treatment unit, the PLAT fuel catalytic reforming unit, the HDS gas oil desulphurization unit and the CRYO and HMP hydrogen production units. The operator set up a crisis unit without triggering the internal emergency plan. The Propane Deasphalting Unit (PDU), Furfural Extraction Unit (FEU) and Viscosity Breaking unit (VBU) re-started on a priority basis. The operator decided to leave the CLAUS 5 unit shut while the CLAUS 4 was still operating. This loss of power supply resulted in a hot oil leak at the oil unit exchangers, spilling of the catalyst from the catalytic cracker unit FCC and the solvent (methyl-ethyl-ketone and toluene) initially onto the ground and then to the drains from the solvent dewaxing units. This accidental release resulted in the COD measured in the oily waters of the platform to exceed for several days. It is also responsible for significant flares (hydrocarbon rate > 110 g for 40 min) and the unstable load of the CLAUS 4 sending hydrocarbons for incineration (due to the overflowing of the amine tower), and triggering a high temperature alert. A sulphur dioxide concentration peak (823 µg/m³) was recorded by the sensors of the air quality monitoring association in the town on 6 November since the SCOT unit treating the tail gases of the CLAUS 4 unit could be re-started only on 7 November due to poor load. Lastly, dispatch of butane and procurement of jet fuel from the refinery were stopped.