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Selection of cables and wires for explosive environments shall comply with the following regulations: (Shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
In explosive environments, the rated voltage of insulating conductors and cables used for low-voltage power and lighting circuits should be higher than or equal to the working voltage, and U0/U should not be less than the working voltage. The rated voltage of the neutral line should be equal to the phase voltage and should be laid in the same sheath or protective tube.
(2) In explosive hazard zones, except within distribution panels, wiring cabinets, or metallic conduit wiring systems, unarmored wires should not be used as supply and distribution lines.
(3) Copper-core cables should be used in Zone 1. In Zone 2, copper-core cables are recommended except for inherently safe circuits. When aluminum-core cables are used, their cross-sectional area must not be less than 16 square millimeters, and copper-aluminum transition joints should be used for connections with electrical equipment. Circuits installed in explosive dust environments in Zones 20 and 21, as well as in areas with severe vibration within Zone 22, must use copper-core insulated conductors or cables.
(4) In addition to the circuit of this pressure safety system, the technical requirements for cable wiring in explosive environments shall comply with the specifications in Table 5.4.1-1.
(5) Technical requirements for steel pipe wiring in explosive environments with voltages below 1000V, excluding circuits of intrinsic safety systems, shall comply with the specifications in Table 5.1.1-2.
(6) In explosive environments, the selection of insulated conductors and cable cross-sections shall comply with the provisions of Tables 5.4.1-1 and 5.4.1-2, as well as the following requirements:
1) The conductor's allowable current should not be less than 1.2 times the rated current of the fuse element and 1.2 times the setting current of the long-time delay overcurrent release of the circuit breaker, except for the case specified in clause 2 of this article.
2) The long-term allowable current for the branch circuit of squirrel-cage induction motors with a voltage rating below 1000V should not be less than 1.2 times the motor's rated current.
(7) When installing overhead or bridge-mounted cables, flame-retardant cables are recommended. Plastic sheathed cables without armor can be used when the installation method employs bridgeways that prevent mechanical damage. Non-armor cables can also be installed in cable trenches within Zones 2 and 22, where there is no risk of damage from rodents or insects.

Standard for explosion-proof construction acceptance — Shenzhen ZhongNuo Testing Technology Co., Ltd.
G50058 Specification for Design of Electrical Installations in Explosive Hazardous Environments
GBJ54-83 "Code for Design of Low-Voltage Distribution Equipment and Lines"
G50016 Building Design Fire Prevention Code
AQ3009 Electrical Explosion-Proof Safety Regulations for Hazardous Areas
GB/T3836.1 "Explosive Atmospheres, Part 1: Equipment - General Requirements"
GB/T3836.15 "Design, Selection, and Installation of Electrical Equipment for Explosive Environments"
GB50257 "Code for Construction and Acceptance of Electrical Installation Works in Explosive and Fire Hazardous Environments"
14J938 "Explosion-Proof and Explosion Ventilation Windows, Roofs, and Wall Building Structures"

Basic Requirements for Explosion-Proof Electrical Installations in Explosive Areas (Shared by Shenzhen ZhongNuo Inspection Technology Co., Ltd.)
1. Oil-immersed equipment should be used under conditions of no vibration, no tilt, and fixed installation.
2. When using non-explosion-proof equipment for mechanical transmission in partition walls, the following regulations shall be observed:
(1) Rooms housing electrical equipment should be separated from the explosive hazard area by non-combustible solid walls.
(2) Transmission shafts passing through walls should be sealed with stuffing box or equivalent sealing measures.
(3) The exit of the room housing electrical equipment should lead to an environment free of explosive hazards.
(4) When the room for installing equipment must be connected to an explosive environment, the explosive environment should be maintained at a relative positive pressure.
3. Electrical lines and equipment in explosive environments, excluding intrinsic safety circuits, should be equipped with overcurrent, short-circuit, and grounding protection. Overcurrent protection is not required for electrical equipment that cannot experience overloading. Motors in explosive environments, in addition to being installed with necessary protections as required by current standards, should also be equipped with phase failure protection. If the automatic shutdown of electrical equipment could pose a greater risk than the ignition hazard, an alarm device should be used in place of the automatic shutdown device.
4. In emergency situations, appropriate measures should be taken at a suitable location outside the hazardous area to disconnect the power to the equipment in the hazardous area. Continuous operating equipment should not be included in the emergency shutdown circuit and should be installed on a separate circuit to prevent the occurrence of additional hazards.
5. The design of substation, distribution substation, and control room shall comply with the following regulations:
Transformer stations, distribution stations (including distribution rooms, etc.), and control rooms should be located outside of explosive atmosphere environments. When they are in positive pressure rooms, they can be arranged in Zones 1 and 2.
(2) For explosive gas atmospheres where the gas is heavier than air, the equipment floor of electrical and instrumentation in substations, distribution stations, and control rooms located in the additional zone 2 of the explosion hazard area should be elevated 0.6 meters above the external ground level.

Basic Dust Explosion Proof Construction Standards
In facilities where explosive dust is present, such as flour mills, feed factories, grinding workshops, and plastic production plants, the requirement for explosion-proof measures on-site is particularly crucial. The installation and use of explosion-proof wiring, electrical equipment, dust removal systems, architectural layout, and explosion-proof venting must all comply with the relevant dust explosion-proof standards. Based on a wealth of explosion-proof electrical construction and modification cases, Shenzhen Zhongnuo Testing Technology Co., Ltd. has summarized the following points:
4. Explosion-proof electrical equipment
Electrical equipment used in hazardous dust explosion areas shall comply with the relevant standards of GB/T3836. The electrical design should be executed in accordance with the provisions of GB50058. Explosion-proof electrical equipment should be selected based on the level of explosion hazard area and the category, grade, and group of explosive hazardous substances.
Options for explosion-proof electrical equipment. In addition to dust-proof electrical equipment with dust-tight construction for the 21-zone environment containing combustible non-conductive dust and combustible fibers, dust-proof electrical equipment with dust-tight construction is used in the 20-zone explosive dust environment and other 21-zone explosive dust environments, and electrical equipment of different ignition temperature groups is selected according to the different ignition temperatures of the dust.
(2) Galvanized Welded Steel Pipe for Low-Pressure Fluid Transmission
(3) Connections between steel pipes, steel pipes and electrical equipment, and steel pipe accessories should be made with threaded connections. Soldering with sleeves is prohibited, and the following requirements must be met:螺纹 should be smooth, complete, and free of rust. Electrical grease or conductive anti-rust grease should be applied to the threads. Do not wrap hemp or insulating tape around the threads, nor apply other paints. Steel pipes with a diameter of 25mm or less should have at least 5 threads, and steel pipes with a diameter of 32mm or more should have at least 6 threads.
(4) Explosion-proof flexible conduits should be installed at the following locations for steel pipe wiring: at the motor's incoming line clamp, where it's difficult to connect steel pipes directly to electrical equipment, and where pipelines pass through the expansion joints and settlement joints of buildings.
(5) In Zones 20, 21, and 22, the use of portable electrical equipment is not recommended. If portable electrical equipment must be used, YC or YCW rubber cables should be selected for the wiring.
AQ3009-2007 "Electrical Explosion Protection Safety Specification for Hazardous Areas" categorizes dust explosion areas into 20 zones, 21 zones, and 22 zones.
5. Ventilation and Dust Removal
(1) It is advisable to set up a dust removal system in opposition, categorized by process sections.
(2) All dust-generating points should be equipped with dust collectors
(3) There should be no dust settlement in the ductwork.
(4) Bag dust collectors should be used, with external filtration type being given priority.
(5) Dust collectors should be installed outdoors. If installed indoors, the explosion relief pipe should directly lead to the outside, with a length less than 3 meters, and a explosion-proof device should be set up based on the dust properties.
(6) It is advisable to install isolation valves at the inlet and outlet of the dust collector and temperature monitoring devices.
(7) Pulse-jet bag dust collector should use nitrogen, carbon dioxide, or other inert gases as the cleaning gas source.
6. Fire Protection
(1) Select the appropriate fire extinguisher based on the physical and chemical properties of the dust.
(2) During extinguishing, prevent dust from being raised to form a dust cloud
(3) If a combustible material reacts with water to produce explosive gases, water should not be used to extinguish the fire.
7. Job Safety
(1) Measures should be taken to prevent collisions from causing dust clouds to ignite when struck by sparks, and at the same time, explosion-proof tools should be used during maintenance.
(2) Do not use rotating grinding wheels and rotating cutting disks for grinding and cutting without equivalent protection measures to those for open flame operations.
(3) All production areas and storage rooms where dust may accumulate should be cleaned promptly.
(4) Do not use compressed air for downhole blowing.
(5) In the workplace, production personnel should not wear close-fitting garments made of synthetic fibers.
Explosion-proof electrical modifications and on-site explosion-proof construction consultation services for hazardous areas - Shenzhen Zhongnuo Inspection Technology Co., Ltd.