IEEE Standard 524a-1993 describes the hazards of induced voltages due to magnetic “elds. The code states

An energized transmission line forms a single loop where the current passes inside the conductor and returns through the ground. The current inside an energized conductor produces a magnetic ¢ux Φ that surrounds the conductor, as shown in Figure 7.1. Ideally, these ¢ux contours are circular and concentric with the conductor.