Overhead power lines have some strict guidelines for height clearances over streets, sidewalks, alleys, roads, and driveways. The National Electrical Code (NEC) mandates acceptable clearances for power lines to keep the public safe from coming into contact with them. You see, cables high enough to avoid a person walking past them, may not be high enough to eliminate the possibility of a large truck or person carrying an extension ladder from coming into contact with it.
That's exactly why the NEC has put these safety standards into practice.
According to the 2008 National Electrical Code, the overhead spans of open conductors and open multiconductor cables of not over 600 volts, nominal, shall have the following clearances for safety. In Article 225.18 of the NEC, the following cable heights must be maintained.
Power Line Clearance: Under 150 Volts
For power lines and conductors above finished grade, sidewalks, or from any platform or projection from which they might be reached where the voltage does not exceed 150 volts to ground and accessible to pedestrians only, should be 10 feet minimum overhead.
For power lines over driveways, non-commercial traffic, and residential property, not exceeding 300 volts, a minimum of 12' clearance is needed. In instances over residential property and driveways, and those commercial areas not subject to truck traffic where the voltage does not exceed 300 volts to ground, should be a minimum of 12 feet overhead clearance.
Power Line Clearance: 300-600 Volts
When we move up to power lines over public streets, roadways without truck traffic and alleys, with voltages of 300-600 volts, a minimum clearance of 15' is required.
And for power lines over alleys, public streets, non-residential driveways, roadways with truck traffic, with maximum voltages of 600 volts, a minimum clearance of 18' is required.
Remember, Just because power lines are strung high enough in normal conditions, icy conditions and downed tree limbs can bring power lines dangerously close, so beware! If a power line or cable looks too low to safely pass beneath it, go around and do not try to pass under it!
Machinery, Trucks and Power Lines
In the case of farm machinery, there is a clear and present danger around power lines. Each year many are injured or killed when coming into contact with power lines. In and around farms and fields there are a number of overhead power lines. When moving tall equipment around the farm, beware of overhead power line dangers. Augers should be cranked down to a safe level when traveling under power lines.
Dump trucks and semis have similar problems when the dump beds are rising up to dump their loads. Be aware of your surroundings when lifting the dump bed and moving the vehicle while the dump is in the up position. When the unloading auger of a combine is turned out to unload, these augers could come in contact with a sagging power line or electrical connection on a power pole. Take time to look over the area before extending the boom. Stay at least 30 feet from all power lines power poles.
Let's take a closer good look around when working around power lines and be sure the power line heights are high enough to safely pass below them. Let's try to help keep everyone safe. If you come across a power line or cable that appears to be strung way too low, call the utility company and have them come and check it out. It's better to be safe than sorry.