Abstract: An apparatus and method of identifying wires or circuits uses plugs with light-emitting diodes ("LED's") attached across the plug contacts corresponding to the wiring circuit. All of the jacks in a terminal or patch panel are filled with such plugs prior to testing and are monitored by a first worker. A second worker, in two-way communication with the first worker, applies a test voltage at the remote terminations of the wires, causing the corresponding LED to light, but no others. The lit LED immediately identifies the circuit, which can be labeled, and the process repeated. When testing is complete, all plugs with LED's are removed from the terminal for re-use.