A group wiring system includes a hub of a server system, a distribution frame including a plurality of wire pair receptacles, a plurality of remote receptacles, a testing device, and a plurality of testing circuits. Each testing circuit is coupled between conductive wires of contacts of an associated wire pair receptacle. Each testing circuit includes a light emitting device and a filtering device. The light emitting device emits light when the testing device applies a testing voltage to the contacts. The testing voltage is a low-frequency voltage signal having a frequency higher than 200 Hz that creates a circuit impedance higher than an impedance of the filtering device when passing through the hub, thereby decaying and filtering the voltage signal and allowing locating test while the server system is on-line. A method for locating wire pairs in a group wiring system is also disclosed.