Phaser banks referred to the phaser weapons mounted aboard Federation starships. They were utilized as early as 2257, when Lieutenant James T. Kirk was manning the phaser station aboard the USS Farragut.
Each bank contined one or more phaser emitters from which the beam energy was actually released but which shared common power sources and targeting systems. Mid-2260s Starfleet phaser banks consisted of one emitter each, and drew power from rechargeable sources separate from a ship's main power systems.
In the 2260s, Constitution-class starships were equipped with at least twelve phaser banks, though they tended to be fired in pairs. The main banks were located on the lower half of the starship's saucer section, forward of the sensor dome. An additional banks were located on the ship's stern, above the shuttlebay. Port and starboard banks covered the ship's flanks.
In the 2270s, a new system, tying the phasers directly into the main reactor, was developed. While increasing phaser power, it had the disadvantage of cutting off most of or all phaser power if the reactor was damaged. ( By the 24th century, the number of emitters in each bank had been increased to the point where they were laid out in long strips called phaser arrays. However, the term "phaser banks" was still used, particularly in reference to units with smaller numbers of emitters. A small Federation phaser bank can be powered by a 4.2 gigawatt power generator