The employees of a roof tile manufacturing plant detected smoke in an electrical room at around 11 a.m. The fire brigade and the electrical utility technicians arrived 10 minutes later. The power was disconnected and the site locked out. Upon entering the equipment room, the firefighters encountered a significant amount of flames and decided to extinguish the fire with carbon dioxide foam.

The incident was attributed to a direct lightning strike on the site at around 10:30 a.m. The strike was located around a lightning rod, not far from the substation. Electrical current travelling into the substation, probably through the earth conductor, set fire to a capacitor bank and caused a transformer to swell.

The consequences of the accident were quite serious. Following the lightning strike, only three analogue phone lines remained in operation and were very quickly saturated with incoming and outgoing calls. The antenna of a mobile telephone operator powered by the factory was also affected. As far as the plant’s production operations are concerned, the kilns were stopped without artificial ventilation. The site’s intrusion protection system was also out of service (video surveillance, closure of gates, alarms, etc.).

The operator had a lightning protection assessment performed on the facilities. The study concluded that the existing lightning rod was ineffective and it was determined that it had in fact been installed before several modifications were undertaken at the site. The manufacturer must modify its facilities accordingly. A global review of the location of the lightning rods, down conductor, earth connection, and the earthing network interconnection in the trench bottom must also be conducted.