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EMT is available in trade sizes 1/2" through 4", and 10′ and 20′ lengths. Some manufacturers also produce EMT in a range of colors for easy system identification. Aluminum conduit, similar to galvanized steel conduit, is a rigid tube, generally used in commercial and industrial applications where a higher resistance to corrosion is needed.
A circular mil is a unit of area, equal to the area of a circle with a diameter of one mil (one thousandth of an inch or 0.0254 mm). It is equal to π /4 square mils or approximately 5.067 × 10 −4 mm 2. It is a unit intended for referring to the area of a wire with a circular cross section.
In both those instances the white wire should be identified as being hot, usually with black tape inside junction boxes. The neutral wire is identified by gray or white insulated wire, perhaps using stripes or markings. With lamp cord wire the ribbed wire is the neutral, and the smooth wire is the hot. NEC 2008 400.22(f) allows surface marking ...
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Such open-wire balanced lines with periodic transpositions still survive today in some rural areas. Twisted-pair cabling was invented by Alexander Graham Bell in 1881. [ 4 ] By 1900, the entire American telephone network was either twisted pair or open wire with transposition to guard against interference.
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.
The wire is not round but has grooves at the sides to allow the hangers to attach to it. Sizes were (in cross-sectional area) 85, 100, or 150 mm 2. To make the wire stronger, 0.04% tin might be added. The wire must resist the heat generated by arcing and thus such wires should never be spliced by thermal means.
The subway-shoving victim who miraculously survived being pushed onto the tracks of an oncoming Manhattan train broke his silence to thank those who helped him after the random New Year’s Eve ...