Stray Voltages from Power Lines

When things such as Fences and pipelines are run parallel to High Voltage Power Lines.  Voltages can be induced in them.  These voltages can either be due to electromagnetic induction caused by transformer action between the pipelines and the power lines or they can be due to electrostatic coupling between the conductors and the pipeline. 
These voltages are usually very weak.  However, the voltages can rise to levels where they present a danger of electrocution. The three phases in the power lines are designed to cancel the magnetic field of one another.  Electromagnetic induction is usually caused when the loading on the three lines is not perfectly balanced.  This problem can be overcome by grounding pipelines and fences at regular intervals.