Power Switch

The Power Switch is a utility found in most Zombies maps. It is not seen in Nacht der Untoten, Shi No Numa, Nuketown or Mob of the Dead. It turns on the power, which in turn is used to use the Pack-a-Punch Machine, Perk-A-Cola machines and other utilities such as Electro-Shock Defenses.

Locations
Information in the descriptions refers to other actions using the power switch does other than those stated above.

Verrückt
The first map with a power switch. It is located on the complete opposite side of the map. The switch is on the opposite side of the room of the Mystery Box. Using it opens the door dividing the two starting rooms.

Der Riese
The switch can be found in the courtyard attached to a giant generator. Using it lowers a bridge that connects the second floor of the two sides and also opens two doors, letting players move from the courtyard to this area directly instead of going through whichever side they unlocked. It also lets the players use the teleporters.

Kino der Toten
The switch is backstage, next to the M16. Using it draws back the curtain, opens the door in the lobby and activates the projector. It also lets Crawler Zombies spawn from then on. It then allows the player(s) to link and use the teleporter.

"Five"
It is found in the central room in the basement. Using it unlocks the teleporters and the DEFCON Switches. It also lets the Pentagon Thief and the Nova Crawlers spawn.

Ascension
Located on the top floor of the main building. Using it activates the Lunar Landers and changes the game from black and white to color.

Call of the Dead
It is located in the uppermost part of the ship. It lets the players use the Flinger and start the Original Characters Trapped Easter egg. It also allows Pack-A-Punch to begin spawning.

Shangri-La
Two power switches are located underground near the Bowie Knife where the water falls from the ceiling to turn the turbines. These power switches activate the water (each switch activating each side) and the power won't turn on until both switches are pulled. Because the switches are associated with water flow, the Water Slide can't be used without them pulled. Turning on the power also lets the player(s) use the Mine Cart.

Moon
The power switch is located in the center of the map by the pyramid and Stakeout. In addition to its basic functions, it restores oxygen and gravity to certain areas of the map and allows the Excavators to start breaching the base.

Green Run
The separate maps do not require a power switch, but Tranzit does. It is located at the Power Plant and needs to be built from three parts: a power board, a lever, and a zombie hand. They can be randomly found: Turning on the power will set the Avogadro free and it will roam the map from then on as a thunderstorm. The power will turn on green streetlights scattered at or between the bus stops that can be used to make portals from the Denizens. It will also open the exit door to Tombstone Soda, the workbench for the electric barrier, and the spool-and-wires piece for the Jet Gun. For the first time in Zombies, the power has the option to be turned off after it has been turned on. This option is required to go forward with Maxis' path in the Tower of Babble Easter egg.
 * In the first hallway upon buying the door to the reactor, against a wall or lying on the floor, opposite the zombie barrier.
 * Scattered around the reactor, varying from lying near a railing, the pipes, or either set of stairs, to laying near boxes at the bottom of the stairs or the one-way ramp.
 * In the same room as the workbench, on the computers to the left and right of the workbench, or in a corner to the right of the zombie barrier.

Die Rise
It is located on the second floor of the second building in a sewing room. Using it will activate the elevators which obtain the Perk-a-Cola machines and Pack-a-Punch inside them and can help the players go up and down floors.

Trivia

 * In "Five", Ascension, Call of the Dead, Shangri-La, and Moon, below the power switch there is text in German that says "Hochspannung Vorsicht! Lebensgefahr!" ("Danger! High Voltage!"). This is because the power switch's model has been reused from Verrückt with slightly different appearances, as in Kino der Toten, where the arm has been removed.
 * There is an unusable power switch found in the building near the ice cave in Discovery.
 * There is a left hand on the power switch in Verrückt and Der Riese.
 * Even though there is no power switch in Shi No Numa, a sign on the zipline next to the starting area says "Switch on power to activate", indicating that electricity was originally going to appear.
 * The map Shangri-La is the first and only map to feature two power switches.
 * All major Easter eggs require the power to be on, but in Tower of Babble, it also needs to be turned off.