Abstract: A system for locking the doors of a trash chute located within a multi-story structure. A beam of radiant energy extends the length of the chute to a receiver, and upon interruption of the beam by blockage of the chute, the receiver transmits a signal to a detector which in turn energizes locking means to lock all entries to the trash chute until the blockage has been removed. Fire-sensing means and a source of water to flood the chute are also utilized should the blockage catch fire before being removed.