Detail of GB 50257-2014

Introduction of GB 50257-2014

1.0.1 This code is formulated to ensure construction and installation quality of electric equipment on fire and explosion hazard, promote progress of construction and installation technology, ensure safe operation of electric equipment in explosion and fire hazard environment and safe of life and properties of the country and people. 1.0.2 This code is applicable to construction and acceptance of electrical equipment installation engineering in the environment where the gas, vapor, dust, fibre explosive mixture and fire hazards substance will be or likely to be produced during production, processing, disposal, transportation or storage. 1.0.3 This code is not applicable to construction and acceptance of electrical equipment installation engineering in the following cases: 1 Subterranean part of underground mine; 2 For manufacturing, using or storing gunpowder, explosive and initiating explosive, fuze and initiating explosive devices etc.; 3 At places with electrical installations for electrolysis and electroplating which adopt electric energy in production and directly associate with the production process; 4 With strong oxidant and materials which may fire voluntarily without an external ignition source; 5 Vehicles for water, land and air transportation and with offshore and on-land oil well platforms; 6 Nuclear island of nuclear power plant; 7 Piping systems for heating, air conditioning, cooking, washing and the similar purposes while adopting flavored gas as the fuel; 8 Within treatment room; 9 Catastrophic event. 1.0.4 Construction and acceptance of electric equipment on fire and explosion hazard shall not only comply with this code but also the current relevant ones of the Nation. 2 Terms 2.0.1 Explosive atmosphere An atmosphere that may keep combustion spreading freely under atmospheric conditions after the mixture of flammable substances (in the forms of gas, vapor, dust, mist, fibre or flying catkin) and air is ignited. 2.0.2 Explosive dust atmosphere An atmosphere that may keep combustion spreading freely under atmospheric conditions after the mixture of flammable substance (in the form of dust, fibre or flying catkin) and air is ignited. 2.0.3 Explosive gas atmosphere An atmosphere that may keep combustion spreading freely under atmospheric conditions after the mixture of flammable substance (in the form of gas or vapor) and air is ignited. 2.0.4 Hazardous area The area in which an explosive mixture is or expected to be present in quantities such as to require special precautions for the construction, installation and use of electrical apparatus. 2.0.5 Zone 0 An atmosphere in which explosive gas mixture is present consecutively or for a long term. 2.0.6 Zone 1 An atmosphere where explosive gas mixture is likely to appear under normal operation. 2.0.7 Zone 2 An atmosphere in which explosive gas mixture may not appear under normal operation or in which the explosive gas only appears in a short time. 2.0.8 Zone 20 The zone where combustible dust cloud persistently or chronically or frequently presents in the explosive atmosphere. 2.0.9 Zone 21 The zone where combustible dust cloud is most likely to occasionally present in the explosive atmosphere under normal operation. 2.0.10 Zone 22 The zone where combustible dust cloud is less likely to present in the explosive atmosphere under normal operation or present in a short time. 2.0.11 Type of protection Various specific measures for electrical equipment to prevent the ignition of surrounding explosive atmospheres. 2.0.12 Intrinsic safety “i” One of types of protection, by limiting the electricity energy in apparatus and interconnecting wire exposed to explosive gas atmosphere to the degree likely to ignite by spark or heat effect. 2.0.13 Intrinsically-safe circuit The circuit by which any electrical spark and any heat effect generated will not ignite the specified explosive gas atmosphere under the normal operating conditions and specified fault conditions. 2.0.14 Intrinsically-safe electrical apparatus Electrical apparatus in which all the circuits are intrinsically safe.

Contents of GB 50257-2014

Foreword I 1 General Provisions 2 Terms 3 Basic Requirements 4 Installation of Explosion-protected Electrical Apparatus 4.1 General Provisions 4.2 Installation of Flame Proof Electrical Apparatus 4.3 Installation of Type of Protection “n” 4.4 Installation of Pressurization “p” 4.5 Installation of Oil Immersion “o” 4.6 Installation of Intrinsic Safety “i” 4.7 Installation of Type of Dust-Ex 5 Electrical Circuit for Explosive Atmosphere 5.1 General Provisions 5.2 Cable Routing for Explosive Atmosphere 5.3 Cable and Wiring in Steel Conduit for Explosive Atmosphere 5.4 Circuit of Intrinsic Safety "i" Apparatus and Relative Apparatus 6 Electrical Apparatus in Fire Hazard Environment 6.1 General Provisions 6.2 Installation of Electrical Apparatus 6.3 Electrical Circuit 7 Grounding 7.1 Protective Grounding 7.2 Anti-static Grounding 8 Project Handover Acceptance Appendix A Electrical Clearance and Creepage Distance between Exposed Live Parts as well as between Exposed Live Part and Metal Enclosure of Explosion-Protected Electrical Equipment Explanation of Wording in This Code List of Quoted Standards