Overhead power lines are subject to strict guidelines for minimum height clearances over streets, sidewalks, alleys, driveways, and other traffic areas. This is a safety consideration, aimed at keeping people safe from the danger of shock. The National Electrical Code (NEC) and National Electrical Safety Code (NESC) mandate acceptable clearances for power lines to keep the public safe and prevent contact with electrical current. Remember, though, that local rules may vary from the national guidelines set forth by the NEC and NESC. They often have stricter guidelines than the national rules. Where discrepancies exist, the local rules always take precedence over the national codes. Contacting your local building inspections office is the best way to determine the rules for your community.
Power Lines Above Pedestrian Sidewalks and Walkways
For power lines above areas used only by pedestrians, including sidewalks, decks, and patios, the rules for minimum vertical clearance of wires above the ground are:
- For lines carrying 150 volts or less: a minimum vertical clearance of 10 feet
- For lines above 150 volts: a minimum vertical clearance of 12 feet
These distances are regarded as enough to provide safe passage to all pedestrians, even when they are carrying tools or other objects. Care should, of course, be used when carrying a ladder or other long object.
Note: where lines are over pathways likely to be used by riders on horseback, the minimum clearance for overhead wires is 16 feet.
Power Lines Over Driveways Without Commercial Traffic
For driveways and other passages used by vehicles that are less than 8 feet in height, the rules for minimum clearances are:
- For lines carrying less than 300 volts: a minimum vertical clearance of 12 feet
- For lines carrying 300 to 600 volts: a minimum vertical clearance of 15 feet
These are the distances used on most residential driveways. Rural homeowners and farmers should use commercial guidelines, since there is a strong likelihood that driveways will be used by service vehicles in rural locations.
Power Lines Over Streets and Roadways With Commercial Traffic
For any driveways, alleys, roads, or streets likely to carry vehicles more than 8 feet in height, the guideline is for all power lines to be at least 18 feet above the ground measured at their lowest point.
Wires Above Pools, Hot Tubs, and Ponds
Electrical wires over water features have unique requirements:
Communication Lines (Telephone, Data) Lines
Rules for vertical clearances for telephone, cable TV, internet, and other data lines varies considerably from community to community, but the NESC sets forth these guidelines:
- For data wires over pedestrian traffic: a minimum vertical clearance of 9 1/2 feet
- For data wires over vehicle traffic: a minimum vertical clearance of 15 1/2 feet
- For data wires over a pool or hot tub: a minimum vertical clearance of 10 feet
Also, there should be 30 inches of clearance between communication lines and electrical service lines.
Remember that minimum vertical clearances must be measured from the lowest point of the wire's droop. You should also accommodate seasonal variations in vertical clearance, such as increasing the clearance in climates where snow cover may reduce the ground-to-wire distance during the winter months.
In the case of farm machinery, there is a clear and present danger around power lines. Each year, many people are injured or killed when their equipment comes into contact with power lines. In and around farms and fields, there are a number of overhead power lines, and when moving tall equipment it's critical that you stay aware of overhead power line dangers. Augers on combines, for example, should be cranked down to a safe level when traveling under power lines. Operators should take time to look over the area before extending the boom and should stay at least 30 feet from all power lines and power poles.
Dump trucks and semi-truck trailers have similar problems when the dump beds are rising up to dump their loads. Drivers must be aware of their surroundings when lifting the dump bed and when moving the vehicle while the bed is in the up position.