Once inside the box, the incoming power is connected to bus bars, which are metal strips that conduct electricity. Depending on the system design, the electricity is regulated to usable voltage levels, such as 120V. A distribution box is a key part of electrical systems in buildings. Inside, you'll find parts like circuit breakers and fuses that protect the system from problems like overloads and short circuits. A distribution box ensures that electrical supply is distributed in the building, also known as a distribution board, panel board, breaker panel, or electric panel. This guide will cover electric distribution boxes, their basics, types, functions.