A fire occurred in a non safety related cabinet, feeding electrically the normal ventilation of the Nuclear Auxiliary Building (controlled area). The fire was discovered by an auxiliary operator restoring the ventilation configuration after completion of a test. The fire was extinguished by the utility rescue squad: the fire brigade, called according to procedures, had no action to take. The event had no impact on safety, and was rated below scale. The utility sent an information release in NUCNET.