The incoming line to a distribution box is called the "incoming line" or "incoming power feed."

The incoming line is the electrical line that brings power from the main supply into the distribution box, which may be a single line or multiple lines, such as a normal supply and a backup supply . It is typically connected to the main circuit breaker or main switch, which protects the distribution system and allows for isolation during maintenance . The incoming line carries the full load current that the distribution box will distribute to various branch circuits . In systems with dual incoming lines, a dual power switch may be installed to automatically switch to a backup supply if the primary line fails, ensuring continuity of power . The incoming line is distinct from outgoing lines, which carry power from the distribution box to individual circuits or loads . Proper labeling and protection of the incoming line are essential for safety and system reliability .