The most common dehumidifier is a rod-type dehumidifier. Approximately 18 inches long and 1/2 inch thick, the dehumidifier is powered by electric current. Almost all safes have a special hole toward the back bottom of the safe for the electric plug to pass through.
A rod dehumidifier slightly heats the air. As the heated air rises to the inside top of the safe, it is vented outward, drawing any moisture with it.
The rod normally works best when it is positioned near the bottom front of the safe, in a horizontal position.