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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 "local" Earth/Ground electrode provides "system grounding" [13] at each building where it is installed. The "Grounded" current carrying conductor is the system "neutral". Australian and New Zealand standards use a modified protective multiple earthing (PME [ 14 ] ) system called multiple earthed neutral (MEN).
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 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.
NEMA 1-15P (two-pole, no ground) and NEMA 5-15P (two-pole with ground pin) plugs are used on common domestic electrical equipment, and NEMA 5-15R is the standard 15-ampere electric receptacle (outlet) found in the United States, and under relevant national standards, in Canada (CSA C22.2 No. 42 [1]), Mexico (NMX-J-163-ANCE) and Japan (JIS C 8303).
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]
The introduction of the NEC clearly states that it is not intended to be a design manual, and therefore creating a colour code for ungrounded or "hot" conductors falls outside the scope and purpose of the NEC. However, it is a common misconception that "hot" conductor colour-coding is required by the Code.
Each phase of the circuit is run in a separate grounded metal enclosure. The only fault possible is a phase-to-ground fault, since the enclosures are separated. This type of bus can be rated up to 50,000 amperes and up to hundreds of kilovolts (during normal service, not just for faults), but is not used for building wiring in the conventional ...