Power transfer over power lines is indicated using a controller to short power lines briefly near the end of the positive portion of the alternating voltage cycle of a distant power generation source using a silicon-controlled rectifier thereby creating current pulses from the voltage produced by that source and at a frequency consistent with the source's electric system frequency. The pulse can be detected and measured on other parts of the same circuit using a probe. The controller and probe may be used for locating cables in the same electrical circuit, sorting particular cables in the same circuit from others cables, verifying the condition of cables, determining the source and load feeds on the primary side of a transformer from the low side of the transformer, locating unwanted ground faults, and determining the portion of the electrical load provided by each of plural generation plants.