According to OSHA (Occupational Safety and Health Administration), MAD (minimum approach distance) from Transmission and Distribution power is dependent on the voltage of the tower. There is no industry standard for how far UAVs should be away from electric towers. Most likely, it is up to the electric company to set its own guidelines. Some companies indicate that 6-10 feet away from isolators is sufficient enough without risk, however it also depends on the type of UAV used for the aerial assessment.
MAD is to ensure that workers do not approach or get closer to the energized parts of T&D lines.
UAV pilots must adjust for altitude correction factors to the minimum approach distances in the table below set by OSHA. As always, we must consider changes in the weather and adjust the minimum approach distances.
Safety is a priority when assessing T&D lines using UAVs. It is the PIC (Pilot in command) responsibility to make sure that the the mission for every tower is a safe one. Launch and landing area must be clear in its surroundings, checklist followed on every flight and most importantly, keep the distance from energized lines. Safe flight everyone. Cheers!