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The National Electrical Safety Code (NESC) or ANSI Standard C2 is a United States standard of the safe installation, operation, and maintenance of electric power and communication utility systems including power substations, power and communication overhead lines, and power and communication underground lines.
The National Electrical Code (NEC), or NFPA 70, is a regionally adoptable standard for the safe installation of electrical wiring and equipment in the United States. It is part of the National Fire Code series published by the National Fire Protection Association (NFPA), a private trade association . [ 1 ]
61 Clearances from buildings of lines of voltage exceeding 650 V 62 Conductors at different voltages on same supports 63 Erection or alteration of buildings, structures, flood banks and elevation of roads 64 Transporting and storing of material near overhead lines 65 General clearances 66 Routes proximity to aerodromes
One drawback of AIS is the visual impact of a larger substation with overhead power lines entering and exiting, which may be unacceptable in scenic or urban areas. [38] AIS requires additional bracing in a seismically active area, and emits more electromagnetic fields and noise than alternative technologies.
Compared to overhead power lines, underground lines have lower risk of starting a wildfire and reduce the risk of the electrical supply being interrupted by outages during high winds, thunderstorms or heavy snow or ice storms. An added benefit of undergrounding is the aesthetic quality of the landscape without the powerlines.
Aerial bundled cables (also aerial bundled conductors or simply ABC) are overhead power lines using several insulated phase conductors bundled tightly together, usually with a bare neutral conductor. This contrasts with the traditional practice of using uninsulated conductors separated by air gaps.
It is used by electrical utility companies as a communications medium, installed along existing overhead transmission lines and often sharing the same support structures as the electrical conductors. [1] [2] ADSS is an alternative to OPGW and OPAC with lower installation cost. The cables are designed to be strong enough to allow lengths of up ...
The code also defines the clearance that is shorter than the physical clearance to account for sag curves, bridge deflection and expected settlements with a recommendation of minimum clearance of 5 metres (16 ft 5 in). [2] In UK, the "standard minimum clearance" for structures over public highways is 16 feet 6 inches (5.03 m). [3]