52.4-B2c)    Supporting Conductors of 7500-20,000 Volts at certain Locations: At All crossings over public thoroughfares and at locations adjacent to structures such as water tanks, windmills and buildings, adjacent to wells, and at similar locations, crossarms supporting conductors of 7500-20,000 volts shall be marked as high voltage.

52.4-B2c)    Supporting Conductors of 7500- 20,000 21,000 Volts at certain Locations: At All crossings over public thoroughfares and at locations adjacent to structures such as water tanks, windmills and buildings, adjacent to wells, and at similar locations, crossarms supporting conductors of 7500-20,000 21,000 volts shall be marked as high voltage.

52.4-B2c)    Supporting Conductors of 7500-21,000 Volts at certain Locations: At All crossings over public thoroughfares and at locations adjacent to structures such as water tanks, windmills and buildings, adjacent to wells, and at similar locations, crossarms supporting conductors of 7500-21,000 volts shall be marked as high voltage.