When activated, the power switch makes the perks purchasable. It was first introduced in the map Observation Deck and makes has made an appearence in most of the newer Zombiecraft Maps.
Hitting the switch with the left click or E button can cause the lever on the switch to go down. from this point, some lights may turn on, the trap will work, and the perks now can be purchased. You can only hit a power switch once in a game.