At a chemical platform whose electricity was being distributed by an entity independent of the site, an outage caused the same effects as those produced 5 days earlier on the same platform: the sulphuric acid (H2SO4), methylmercaptan (MeSH) and carbon disulphide (CS2) units automatically switched into safety position with the discharge of 750 kg of sulphur dioxide (SO2) into the atmosphere via the site’s flares. These releases, which lasted 10 to 15 min on both the MeSH and CS2 workshops, were quickly dispersed by a strong wind. The release via the H2SO4 workshop flare lasted 90 min. The facility’s internal emergency plan was activated. Two subcontracted technicians working on a platform site, disturbed by the SO2 odour, were treated at the local infirmary and sent home. A very slight sulphur smell was at times noticeable within municipalities close to the site. Neighbouring town halls were kept informed. The reading recorded by the local air quality monitoring office showed an SO2 concentration peak of 0.675 mg/m³. Electrical power was restored to the workshops 70 min after the accident, and the emergency plan was lifted 90 min later. A defective cable found on the platform’s western high-voltage station was the source of this outage: its electronic protection had been placed in an ‘earth fault’, and then this fault was extended to the general high voltage station. To reduce the probability of recurrence for such an accident, the western station cell was insulated, to prevent a fault from relaying to the main cell, all the way to the defective cable replacement.