Several systems and methods for monitoring the proximity of a device to a power line are disclosed. Electric field monitoring systems are mounted to the device and include a plurality of electric field sensors and a monitoring system base unit. Each electric field monitoring sensor senses the strength of a magnetic field in which the sensor is positioned and transmits a corresponding magnitude output signal to the base unit when polled by the base unit. If a sensor reports a magnetic field exceeding a threshold, the frequency of polling for that sensor may be increased. If a sensor reports a magnetic field exceeding another (possibly identical) threshold, an alarm may be activated, movement of the device may be limited or stopped or another action or a combination of actions may be taken.