Lightning fell onto a lightning rod designed to protect a building used for assembling launchers and space vehicles. The equipment sustained damage as did the fire prevention system, causing halon to leak. The thrusters were protected and the workshop area evacuated and ventilated. All contract personnel exposed to the halon gas were examined and no adverse reaction was detected. The resumption of plant activities was conditional upon complete restoration of the protection systems. The inerting system was affected by reverse lightning currents, which created a signal similar to the activation signal (i.e. resultant from activation of 2 fire detectors). In the future, the electrical circuits will be protected by lightning arresters.