National Electrical Safety Code (NESC) Questions
What is the NESC vertical clearance above ground or roads?
NESC Rule 232 covers the "vertical clearances of wires, conductors, cables, and equipment above ground, roadway, rail, or water surfaces." The required clearances above roads, streets, driveways, parking lots, and other land traversed by vechicles, such as cultivated, grazing, forest, or orchard land are shown below.
|Item||Cable or Conductor||NESC Clearance||Comments|
|A||Phase||18.5 ft||Applies to phase wires 22kV and below. For voltages above 22kV phase-to-ground, see NESC Rules 232C and 232D.|
|B||Neutral||15.5 ft||Applies to neutrals meeting NESC Rule 230E1.|
|C||Secondary||16.0 ft||Applies to secondaries 750V or less meeting NESC Rule 230C2 or 230C3 (triplex, quadruplex, etc.).|
|D||Communication||15.5 ft||Applies to cable TV, phone, fiber optic cables, etc.|
- Permitting entities such as state highway departments, counties, and cities may require additional clearances.
- Clearances shown are required during the temperature and loading conditions detailed in NESC Rule 232A and must be maintained at the worst case clearances at 32°F with ice from the applicable loading zone, 120°F, or greater than 120°F if so designed. Since the NESC requires the clearances to be maintained under specified conditions, a sag chart is required to know if clearance is meets the Code requirements.
- See NESC Table 232-1 for footnotes that allow certain reductions depending on the nature of the surface under the line.
The information presented above attempts to answer common questions about the NESC to help the reader understand the Code. Additional rules may apply and the reader should use this information only as a starting point to aid in reading the Code and investigating the actual Code requirements for the situation under consideration.