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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.
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
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 ]
The clearance for overhead signs is 5.7 metres (18 ft 8 in) and the clearance for the soffit or underside of overpasses is 10 metres (32 ft 10 in). [ 6 ] In South Africa and the southern region of Africa, the minimum vertical clearance of modern bridges is 5 metres (16 ft 5 in), although the legal height limit of road vehicles is still at 4.3 ...
The lifetime cost difference is smaller for lower-voltage distribution networks, in the range of 12–28% higher than overhead lines of equivalent voltage. [12] Whereas finding and repairing overhead wire breaks can be accomplished in hours, underground repairs can take days or weeks, [13] and for this reason redundant lines are run.
The service drop provides the building with two 120 V lines of opposite phase, so 240 V can be obtained by connecting a load between the two 120 V conductors, while 120 V loads are connected between either of the two 120 V lines and the neutral line. 240 V circuits are used for high-demand devices, such as air conditioners, water heaters ...
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.
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.