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Installation of electrical wiring in explosive environments shall comply with the following regulations (shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
Electrical wiring should be installed in environments with lower explosion hazards or far from the source of release, and it should comply with the following regulations:
1) When the weight is heavier than air, electrical wiring should be installed at a higher level or directly buried. For overhead installation, cable trays should be used; for trench installation, the trench should be filled with sand, and drainage measures should be provided.
2) Electrical wiring should be laid outside the walls of buildings or structures that pose an explosion hazard.
3) In explosive dust environments, cables should be laid in areas where dust does not accumulate easily and is easy to dust off.
(2) Holes in walls or floors between different areas traversed by electrical wiring conduits, cable trays, or ducts should be tightly sealed with non-combustible materials.
(3) When laying electrical lines, it is advisable to avoid areas prone to mechanical damage, vibration, corrosion, ultraviolet radiation, and potential heat exposure. If avoidance is not possible, preventive measures should be taken.
(4) Wiring with steel pipes can use insulated single-core or multi-core wires without sheathing. When the steel pipe contains three or more wires, the total cross-sectional area of the wires including the insulation should not exceed 40% of the steel pipe's cross-sectional area. The steel pipes should be of low-pressure fluid transportation lock zinc welded pipes. The threaded section of the steel pipe connections should be coated with lead oil or phosphating paste. At locations where condensation water may form, sealed joints for condensation water drainage should be installed on the pipeline.
(5) Electrical wiring for steel pipe conduit in explosive gas environments must be properly insulated and sealed, and should comply with the following regulations:
1) During normal operation, the 450mm range around all ignition source enclosures should be sealed off.
2) Steel pipes with a diameter of 50mm or more should be isolated and sealed within 450mm of the junction box.
3) Isolation and sealing should be provided between adjacent explosive atmospheres, as well as between explosive atmospheres and adjacent other hazardous or non-hazardous environments. During sealing, the internal surface of the seal should be lined with a fibrous filling layer or separator. The effective thickness of the filling layer should not be less than the inner diameter of the steel pipe and must not be less than 16mm.
4) Components for isolation sealing should not be used for wire connections or branching.
(6) Intermediate joints are strictly prohibited in cable lines within Zone 1, and intermediate joints should not be present in Zones 2, 20, and 21.
(7) When connecting cable or wire terminals, if the internal wires are stranded, they should be connected using a molded terminal or lug. The connection and termination of aluminum-core insulated conductors or cables should be done by crimping, soldering, or brazing. When connecting to equipment (excluding lighting fixtures), a copper-aluminum transition joint should be used.
(8) Overhead power lines must not cross explosive gas environments. The horizontal distance between overhead lines and explosive gas environments should not be less than 1.1 times the height of the tower. In special cases, after taking effective measures, the distance may be appropriately reduced.

Basic Requirements for Explosion-Proof Electrical Installations in Hazardous Areas (Shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
1. Oil-immersed equipment should be used under conditions of no vibration, no tilting, and fixed installation.
2. When using non-explosion-proof equipment for mechanical transmission as 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) The drive shaft should be sealed at the partition wall with gland packing or an equivalent sealing method.
(3) The exit of the electrical equipment room should lead to an environment free of explosive hazard areas.
(4) When the room housing the equipment must be connected to an explosive atmosphere, the explosive atmosphere should be maintained at a positive pressure relative to the room.
3. Electrical wiring 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 overloads. Motors in explosive environments should be fitted with phase failure protection in addition to the necessary protection as required by current standards. If the automatic shutdown of electrical equipment may pose a greater danger than the ignition risk, an alarm system should be used instead 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 switchrooms, etc.), and control rooms should be located outside of explosive atmosphere environments. When they are positive pressure rooms, they can be arranged in Zones 1 and 2.
(2) For explosive gas environments heavier than air, the equipment floors of electrical and instrumentations in power 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 Safety Regulations for Explosion-Proof Design in Hazardous Areas (Shared by Shenzhen Zhongnuo Testing Technology Co., Ltd.)
1. Initial explosion protection overall design
2. Directed release of explosive energy. Around the explosion source, comprehensively utilize anti-explosion and venting technologies. Set anti-explosion walls and windows in the direction of high population density, office areas, and critical equipment. In areas with low human traffic and no critical equipment, install venting walls and windows.
3. Establish safe distances. Minimize the placement of office areas, residential zones, and critical equipment areas within the range less than the safe distance unless necessary; if they are set, necessary anti-explosion measures should be taken.
4. Conversion of non-blast-resistant buildings to blast-resistant structures. In the range less than the safe distance, buildings should undergo blast-resistance assessment, and those that do not meet the blast-resistance requirements should be reinforced with blast-resistant measures: prevent building collapse; prevent the fracturing of brittle materials like bricks, concrete, glass, etc., leading to debris ejection.
5. Place explosion-proof shelters in hazardous blast areas.

Basic Knowledge and Requirements for防爆 Cable Use on Construction Sites (Shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
Installation methods for electrical wiring in explosive gas environments can be categorized into cable wiring and conduit wiring methods.
Note: The installation of inherently safe circuits may not follow the provisions of this section.
7.1 General Provisions
7.2 Electrical wiring should be installed in areas with lower explosion hazards or at a greater distance from the source of release, avoiding locations prone to mechanical damage, vibration, corrosion, dust accumulation, and those with hazardous temperatures. When avoidance is not possible, preventive measures should be taken.
7.3 The selected low-voltage cables or insulated conductors must have a rated voltage higher than the working voltage of the line, but not less than 500V. Insulated conductors must be laid inside conduits.
7.4 Prohibition of overhead lines at 10kV and below crossing explosive gas environments; the horizontal distance between overhead lines and explosive gas environments should not be less than 1.1 times the height of the poles.
7.5 Cables and accessories shall be installed in such a position that, in accordance with the actual conditions, they are protected against external mechanical damage, corrosion, or chemical effects (such as the influence of solvents), as well as the effects of high temperatures (also see 6.1.2.4.4 for this safety circuit). If these conditions cannot be avoided, protective measures should be taken during installation, such as using conduits or selecting appropriate cable types (armored cables, shielded wires, seamless aluminum sheathed cables, mineral insulated metal sheathed cables, or semi-rigid sheathed cables, etc., to minimize damage).
7.6 Unsheathed single-core wires should not be used for conductive wiring unless they are installed within a distribution board, enclosure, or conduit system.
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