National Electric Code area classification

Electiical classification. Article 500 of the National Electric-Code provides for the classification of the hazardous nature of the process area in which the measurement device will be installed. If the measurement device is not inherently compatible with this classification, suitable enclosures must be purchased and included in the installation costs. 

The design of electrical equipment and instrumentation is based on the nature of the process hazards or specific process classifications. The classification method is defined in the National Electrical Code it is a function of the nature and degree of the process hazards within a particular area. The rating method includes Classes I, II, and III, Groups A-G, and Divisions... 

Table 2.2(a) Classification system for hazardous areas (USA National Electrical Code, NEC, and Canada Canadian Electrical Code, CEC)... 

Among the ANSI standards is the National Electrical Code (NEC) which is directed at the elimination or control of electrical hazards. It defines the classification of areas according to the degree of hazard possibly foimd in the atmosphere and prescribes wiring methods, grounding, control, etc. These factors are important in motor selection. The NEC is a product of the National Fire Protection Association (NFPA). 

In the US, the electrical area classification for areas that contain flammable/ combustible liquids and gases are usually defined by the requirements of the National Electrical Code (NEC), i.e., NFPA 70, API RP 500, and NFPA 30, which are similar in content. 

Electrical Classification. In those areas of the plant where a hazardous quantity of dust accumulates or is suspended in the air, the area should be classified and all electrical equipment and installations in those areas should comply with Article 502 or Article 503 of NFPA 70, the National Electrical Code,... 

An area or a zone defined as a three-dimensional space in which a flammable atmosphere is or may be expected to be present in such frequencies as to require special precautions and restrictions for the construction and use of electrical apparatus and hot surface exposures (e.g., lights) that act as an ignition source. Classified areas have specific restrictions based on the equipment involved, the gases encountered, and the probability of leakage. Several national and industry institutions have guidelines and codes for the classification of areas, e.g., defined in the United States by the National... 

---