Codes, electrical systems National Electric

Beyond perfonnance optimization, issues relative to packaging and the need for compliance with certain safety and electronics regulatory codes are cited as reasons for a customized solution. In the latter case, a systems approach is required, especially when attempting to meet the code or performance requirements for compliance with European Certification (CE) mark or electrical and fire safety codes such as National Eire Prevention Association (NFPA) and CENELEC (European Committee for Electrotechiucal Standardization). Off-the-shelf electronics may provide the necessary performance characteristics for generic applications, and their use eliminates large expenses related to product development, plus the associated time delays. Photonics-related components are solely addressed in this section because they are used to customize instruments for application-specific systems. 

ANSI/NFPA 70 Article 692—Fuel cell systems national electrical code (United States)... 

The first section Installation of Electrical Systems, 1910.302 to. 308, for the most part, covers installation of electrical equipment. Its use is very similar to the National Electrical Code electrical equipment installation. However, there are some sections of the installation requirements that do cover electrical safety. The primary example is providing appropriate working space for equipment likely to require examination, adjustment, servicing, or maintenance while energized. That working space is generally built-in when electrical equipment is installed. The requirements for ground-fault circuit interrupters are another example. 

Explosion-proof enclosures are characterized by strong metal enclosures with special close-fitting access covers and breathers that contain an ignition to the inside of the enclosure. Field wiring in the hazardous environment is enclosed in a metal conduit of the mineral-insulated-cable type. All conduit and cable connections or cable terminations are threaded and explosion-proof. Conduit seals are put into the conduit or cable system at locations defined by the National Electric Code (Article 501) to prevent gas and vapor leakage and to prevent flames from passing from one part of the conduit system to the other. 

It is essential that the process hazardous atmosphere and the process system and handling of combustible hydrocarbons/chemicals be recognized in the physical designs by conforming to the appropriate class of atmos-phere/environment codes specified by the National Electrical Code [71, 83, and 84]. 

Pressure vessels and appurtenances should be constructed of stainless steel or other corrosion-resistant materials. Ideally, these steam generators should receive hot demineralized FW to minimize chemical treatment requirements. Alternatively, where a main boiler plant is installed, 100% steam condensate provides a good source of FW. In practice, it is very difficult to accurately control the correct amount of chemical feed. Chemicals are typically restricted to potable grade, deposit control agents such as polyacrylates, and other materials listed under the Code of Federal Regulations, CFR 21 173.310, or National Sanitary Foundation (NSF International) approval system. These boilers may be electrically heated or gas-fired. 

At all intakes for fresh air or HVAC systems to buildings in an electrically classified area according to the National Electrical Code (NEC) or subject to ingestion of combustible vapors. Especially if they are considered inhabited, critical or of a high value. Typically control rooms, critical electrical switchgear, or main process area power sources are provided with gas detection. 

NFPA 70 National Fire Protection Association 70 is also known as the National Electric Code (NEC). Revisions and addendum s to the code are currently being developed that specifically address fuel cells. Article 690 - Solar Photovoltaic Systems has been targeted for revision to include fuel cells and alternate energy sources systems. This proposal is not expected to be approved since the technological and operational differences between fuel cells and photovoltaic systems is considerable. A new article, currently identified and Article 691, has been proposed and applies to fuel cells for buildings or residential dwellings. This standard addresses the electrical interface between the fuel cell system and a building s electrical distribution panel. 

Each year, statistics on causes and occupancies of fires and deaths resulting from fire are compiled and published. NFPA sponsors seminars on the Life Safety Codes, National Electrical Code, industrial fire protection, hazardous materials, transportation emergencies, and other related topics. NFPA also conducts research programs on delivery systems for public fire protection, arson, residential fire sprinkler systems, and other subjects. NFPA publications include National Fire Codes Annual, Fire Protection Handbook, Fire Journal and Fire Technology. 

Grounding of electrical systems is mandated by the electrical codes that govern the operation of electrical power systems. The National Electrical Code (NEC) in the U.S. is the body that lays out requirements for electrical systems for premises. However, the NEC does not cover installations in ships, railways, or aircraft or underground in mines or electrical installations under the exclusive control of utilities. 

Environmental Enclosures Enclosures for valve accessories are sometimes required to provide protection from specific environmental conditions. The National Electrical Manufacturers Association (NEMA) provides descriptions and test methods for equipment used in specific environmental conditions in NEMA 250. IEC 60529, Degrees of Protection Provided by Enclosures (IP Code), describes the European system for classifying the degrees of protection provided by the enclosures of electrical equipment. Rain, windblown dust, hose-directed water, and external ice formation are examples of environmental conditions that are covered by these enclosure standards. 

In Canada, the system is somewhat similar to the United States, in the development of building codes and an electrical code, but the organization developing them is a part of the National Research Council, and not a separate standards developing organization, as in the United States. 

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

A detailed account of the factors to be considered when designing electrical distribution systems for chemical process plants and the equipment used (transformers, switch gear, and cables) is given by Silverman (1964). Requirements for electrical equipment used in hazardous (classified) locations are given in the National Electrical Code (NFPA 70), as described in Section 9.3.5. 

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