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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 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 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 ...
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 United States National Electrical Code requires a bare copper, or green or green/yellow insulated protective conductor, a white or grey neutral, with any other colour used for single phase. The NEC also requires the high-leg conductor of a high-leg delta system to have orange insulation, or to be identified by other suitable means such as ...
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 ground loop still exists, but the two sides of the loop are close together, so stray magnetic fields induce equal currents in both sides, which cancel out. Break in the shield Create a break in the signal cable shield conductor. [5] The break should be at the load end. This is often called ground lifting. It is the simplest solution; it ...
To avoid electrochemical corrosion, the ground electrodes of such systems are situated apart from the converter stations and not near the transmission cable. The electrodes can be situated in the sea or on land. Bare copper wires can be used for cathodes, and graphite rods buried in the ground, or titanium grids in the sea are used for anodes.