Wiktionary
n. A box that is the source that sends the electricity to the houses in that part of the neighborhood.
Wikipedia
A power box (USA) or feeder pillar (UK) is a cabinet for electrical equipment, mounted in the street and controlling the electrical supply to a number of houses in a neighborhood. A power box is simply a layman's term for a transformer, cutout enclosure, or other enclosure used in conjunction with underground electrical distribution. In the United States, they are often painted olive drab (an olive-like green color), gray or "sand", a light tan color.
Usage examples of "power box".
Four executions in seven years, and all of a sudden, the state had to send in electricians to monkey with the power box.
The new lead from the power box snaked smoothly down to the water and up the dark flank of the seaplane tender.
IfPater's restaurant caused the next buildingto fall, the power box would be destroyed, causinguntold havoc and destruction.