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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 outer jacket is labeled with letters that show how many insulated wires are concealed within the sheath. This does not include the uninsulated ground wire.
For example, NM 14-2 cable contains three conductors (two plus one ground) at 14 gauge, a size typically used for circuits protected at 15 amperes. Circuits with larger currents (such as for electric furnaces, water heaters, air conditioners, or sub-mains to additional circuit panels) will have larger conductors.
A typical panel would be cut to allow 1/4" (5 mm) between itself and the bottom of the groove in the frame. It is common to place some sort of elastic material in the groove between the edge of the panel and the frame before assembly. These items center the panel in the frame and absorb seasonal movement.
[1] [2] The use of concrete enclosed grounding conductors was added to the U.S. National Electrical Code (NEC) in 1968. It was not required to be used if a water pipe or other grounding electrode was present. In 1978, the NEC allowed 1/2 inch rebar to be used as a grounding electrode [NEC 250.52(A)(3)].
Braced frame construction, also known as full frame, half frame, [6] New England braced frame, [7] combination frame, [8] is an early form of light framing developed from the heavier timber framing which preceded it. It is defined by the continued use of girts, corner posts, and braces.
A distribution board (also known as panelboard, circuit breaker panel, breaker panel, electric panel, fuse box or DB box) is a component of an electricity supply system that divides an electrical power feed into subsidiary circuits while providing a protective fuse or circuit breaker for each circuit in a common enclosure.
An optical ground wire (also known as an OPGW or, in the IEEE standard, an optical fiber composite overhead ground wire) is a type of cable that is used in overhead power lines. Such cable combines the functions of grounding and communications .
Steel frame structure Rectangular steel frame, or "perimeter frame" of the Willis building (at right) contrasted against the diagrid frame at 30 St Mary Axe (at center), in London. Steel frame is a building technique with a " skeleton frame" of vertical steel columns and horizontal I-beams , constructed in a rectangular grid to support the ...