The size of a distribution box depends on your circuit capacity and power requirements. For example, a small apartment might. A distribution box, also known as a distribution board, electrical panel, or breaker box, is an enclosure that houses electrical components responsible for distributing electricity throughout a building. You'll find these in almost every residential or commercial building. For example, in a house, it might be mounted near the meter. A suitable choice helps improve safety, reliability, and long-term performance.