Unlike the cold cathode lamps that are used with most neon tubing, fluorescent lights are hot cathode lamps. These lamps are made from wide glass tubes covered in a blend of fluorescent powders. The lamp is filled with a small amount of mercury and a special blend of gasses, evacuated, and assembled with its electrodes. This is not dissimilar to the composition of other neon lights. The use of this type of lamp differs from ordinary neon tubing, however, in the fact that the electrodes are heated before making contact with the electrical arc-which is located between the electrodes.
High voltage is necessary to ensure the contact of the electrodes with the dividing arc.
Used to guarantee this connection is a transformer called a ballast. The ballast takes in the regular electrical current and voltage, and releases it with the needed charge. The ballast also maintains the balance of the arc. Upon the initial starting of the lamp, the ballast must create a high enough voltage for the arc to move across the air and into its designated space between electrodes. After this starting charge, the ballast reduces its voltage output and supports the arc in that area.