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The U.S. NEC and the UK's BS 7671 list systems that are required to be grounded. According to the NEC, the purpose of connecting an electrical system to the physical ground (earth) is to limit the voltage imposed by lightning events and contact with higher voltage lines.
The US National Electrical Code permitted the use of the supply neutral wire as the equipment enclosure connection to ground from 1947 to 1996 for ranges (including separate cooktops and ovens) and from 1953 to 1996 for clothes dryers, whether plug-in or permanently fixed, provided that the circuit originated in the main service panel. Normal ...
In some areas (like Des Moines, Iowa) Ufer grounds are required for all residential and commercial buildings. [5] The conductivity of the soil usually determines if Ufer grounds are required in any particular area. An Ufer ground of specified minimum dimensions is recognized by the U.S. National Electrical Code as a grounding electrode. [6]
The National Electrical Code (NEC) specifies that the black conductor represent the hot conductor, with significant voltage to earth ground; the white conductor represent the identified or neutral conductor, near ground potential; [11] and the bare/green conductor, the safety grounding conductor not normally used to carry circuit current.
The electrodes for electrical grounding are often called ground rods and are often made from steel with a copper clad surface – typically 1 to 2 m long and 20 millimetres (0.79 in) in diameter. These are driven vertically into the ground and bonded together with bare copper wire. [1]
The National Electrical Code, 2008 edition. 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 ground reference for all equipment inside the area being protected is separate from the halo. The halo is connected to the main building ground, which may include an underground ring ground outside the building, with vertical conductors especially in the corners of the building.
Single-wire earth return (SWER) or single-wire ground return is a single-wire transmission line which supplies single-phase electric power from an electrical grid to remote areas at lowest cost. The earth (or sometimes a body of water) is used as the return path for the current, to avoid the need for a second wire (or neutral wire ) to act as a ...