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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 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 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.
While the various OSHA, ASTM, IEEE and NEC standard provide guidelines for performance, NFPA 70E addresses practices and is widely considered as the de facto standard for Electrical Safety in the Workplace. Practices include: Staging a "safe work zone" with boundaries, barricades, signs and attendants.
The NEC refers to this type of ground as a "Concrete Encased Electrode" (CEE) instead of using the name Ufer ground. Over the years, the term "Ufer ground" has become synonymous with the use of any type of concrete enclosed grounding conductor, whether it conforms to Ufer's original grounding scheme or not. [3]
A halo ground is a type of ring ground that, instead of being installed outside and underground, is installed inside, near the top of a building or structure. The ground reference for all equipment inside the area being protected is separate from the halo.
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 ...