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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.
A great deal of THWN wire is actually dual-rated, and meets THHN the specification as well, so may be used in wet environments up to 75°C or dry environments up to 90°C. An extended specification, THWN-2 permits use in wet locations and conductor temperatures up to 90°C simultaneously. [18]
A full-load wire does heat up slightly due to the metallic resistance of the wire, but this wire heating is factored into the cable's temperature rating. (NEC 310.10) [12] The NEC specifies acceptable numbers of conductors in crowded areas such as inside conduit, referred to as the fill rating.
Outside plant cabling, whether copper or fiber, is generally installed as aerial cable between poles, in an underground conduit system, or by direct burial. [2] Hardware associated with the outside plant must be either protected from the elements (for example, distribution frames are generally protected by a street side cabinet) or constructed ...
White: 14 AWG wire (2.08 mm 2) for 15-amp circuits Yellow: 12 AWG wire (3.31 mm 2) for 20-amp circuits Orange: 10 AWG wire (5.26 mm 2) for 30-amp circuits Black: 6 or 8 AWG wire (13.3 mm 2 or 8.37 mm 2) for 60- and 45-amp circuits, respectively Grey: usage for underground installations, designated as "underground feeder" (UF) cables [4]
The first electrical codes in the United States originated in New York in 1881 to regulate installations of electric lighting. Since 1897 the US National Fire Protection Association, a private non-profit association formed by insurance companies, has published the National Electrical Code (NEC). States, counties or cities often include the NEC ...
Cross-section of direct buried cable. Direct-buried cable (DBC) is a kind of communications or transmissions electrical cable which is especially designed to be buried under the ground without any other cover, sheath, or duct to protect it. [1] Most direct-buried cable is built to specific tolerances to heat, moisture, conductivity, and soil ...
However, depending on the depth of the underground cable; greater EMF may be experienced on the surface. [4] The electric current in the cable conductor produces a magnetic field, but the closer grouping of underground power cables reduces the resultant external magnetic field, and further magnetic shielding may be provided.