Larger commercial, public, and industrial installations generally use three-phase supplies, with distribution boards which have twin vertical rows of breakers. Larger installations will often use subsidiary distribution boards.OverviewA distribution board (also known as panelboard, circuit breaker panel, breaker panel, electric panel, fuse box or DB box) is a component of an that divides an electrical power feed into subsidiary. North American distribution boards are generally housed in enclosures, with the positioned in two columns operable from the front. Some panelboards are provided with a door covering th.