Shenzhen Zhongnuo Testing Technology Co., Ltd. is based in South China, offering on-site explosion-proof construction, safety inspections, renovations, project acceptance, and explosion-proof installation consulting services. We are well-versed in explosion-proof construction standards, boasting experienced construction teams and a wealth of practical experience. We have served major corporations such as PetroChina, LG, Hanlan Environment, BOE Technology Group, and Sinovac Biotech, receiving consistent praise and trust from our clients!
Selection of cables and wires for explosive environments shall comply with the following specifications: (Shared by Shenzhen Zhongnuo Testing Technology Co., Ltd.)
In explosive environments, the rated voltage of insulated conductors and cables used for low-voltage power and lighting circuits should be higher than or equal to the working voltage, with U0/U not 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 conduit.
(2) In areas where explosion hazards exist, except within distribution panels, wiring cabinets, or wiring systems using metal conduits, uninsulated wires should not be used as supply and distribution lines.
(3) Copper-core cables should be used in Zone 1. In Zone 2, it is recommended to use copper-core cables, except for inherently safe circuits. When aluminum-core cables are used, the cross-sectional area should not be less than 16 square millimeters, and copper-aluminum transition joints should be used for connections to electrical equipment. Circuits laid in explosive dust zones 20 and 21, as well as in areas with severe vibration within Zone 22, should 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) The technical requirements for pipeline wiring in explosive environments with voltages below 1000V, excluding circuits of intrinsic safety systems, shall comply with the specifications of Table 5.1.1-2.
(6) In explosive atmospheres, the selection of insulated conductors and cable cross-sections shall comply not only with the requirements of Tables 5.4.1-1 and 5.4.1-2, but also with the following provisions:
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 set 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 of the auxiliary line for squirrel-cage induction motors with voltage less than 1000V should not be less than 1.2 times the rated current of the motor.
(7) When installing overhead or bridge cabling, it is advisable to use flame-retardant cables. When the installation method employs bridge supports that prevent mechanical damage, plastic sheathed cables can be used as non-armored cables. When there is no risk of damage from rodents or insects, non-armored cables can be installed in cable trenches in Zones 2 and 22.

Equipment grounding in explosive environments shall comply with the following regulations (shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
In accordance with the relevant provisions of the current standard "Code for Design of Grounding for AC Electrical Installations" GB/T50065, the following parts that do not require grounding should still be grounded in explosive environments:
1) Equipment with a normal non-electrified metal casing, where the alternating current rated voltage is below 1000V and the direct current rated voltage is below 1500V, on不良conducting surfaces.
2) Equipment with a rated AC voltage of 127V or less and a DC voltage of 110V or less, in a dry environment, is commonly not equipped with an energized metal housing.
3) Equipment installed on a grounded metal structure.
(2) In explosive hazard environments, the exposed conductive parts of the equipment should be reliably grounded. All equipment within explosive atmosphere zones 1, 20, and 21, as well as other equipment within explosive atmosphere zones 2 and 22 except for lighting fixtures, should use dedicated grounding cables. If these grounding cables are installed in the same protective conduit as the phase wires, they should have insulation equal to that of the phase wires. Lighting fixtures within explosive atmosphere zones 2 and 22 can utilize a metallic piping system with a reliable electrical connection as a grounding cable, but not pipes for conveying substances.
(3) In different directions of the slope in the explosive hazard area, the grounding main should be connected to the grounding body at least twice.

Standard for Explosion-proof Construction Acceptance - Shenzhen ZhongNuo Inspection & Testing Technology Co., Ltd.
G50058 Design Specification for Electric Equipment 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 Code 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 in Explosive and Fire Hazardous Environments"
14J938 "Explosion-Proof and Explosion Ventilation Windows, Roofs, and Wall Building Structures"

Installation of electrical wiring in explosive environments shall comply with the following regulations (shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
(1) Electrical wiring should be installed in environments with lower explosion hazards or far from release sources, and should comply with the following regulations:
1) When the weight is heavier than air, electrical wiring should be laid at a higher level or directly buried; overhead installation should use cable trays; when using cable trenches, the trench should be filled with sand, and drainage measures should be set up.
2) Electrical wiring should be laid outside the walls of buildings or structures where explosive hazards are present.
3) In explosive dust environments, cables should be laid in areas where dust does not accumulate easily and is easy to dust.
(2) Holes in walls or floors between different areas traversed by electrical line trenches, cable trays, or conduits should be tightly sealed with non-combustible materials.
(3) When laying electrical lines, it is advisable to avoid areas susceptible to mechanical damage, vibration, corrosion, ultraviolet radiation, and heat. If unavoidable, preventive measures should be taken.
(4) Steel pipe wiring can use insulated single-core or multi-core conductors without sheath. When the steel pipe contains three or more conductors, the total cross-sectional area of the conductors including the insulation should not exceed 40% of the steel pipe's cross-sectional area. The steel pipe should be of the galvanized焊接 steel pipe used for low-pressure fluid transmission. The threaded part of the steel pipe connection should be coated with lead oil or phosphating paste. At locations where condensation water may form, a sealed joint for condensation water drainage should be installed on the pipeline.
(5) Electrical wiring for piping in explosive gas environments should be properly insulated and sealed, and should comply with the following regulations:
1) During normal operation, the 450mm area around all ignited 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 incoming junction box.
3) Isolation and sealing should be implemented between adjacent explosive environments, as well as between explosive environments and adjacent other hazardous or non-hazardous environments. When sealing, the inner surface of the seal should be lined with a fibrous layer as the bottom or separator, with the effective thickness of the filling layer not less than the inner diameter of the steel pipe and at least 16mm.
4) Connection components for isolation sealing should not be used for wire connections or branching.
(6) Intermediate joints are strictly prohibited in Cable Lines within Area 1, and intermediate joints should not be present in Areas 2, 20, and 21.
(7) When terminating cables or wires, if the internal conductors are braided, they should be connected using a molded connector or a splicing ferrule. The termination of aluminum-core insulated conductors or cables should be done via crimping, soldering, or brazing. When connecting to equipment (excluding lighting fixtures), a copper-aluminum transition fitting 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 circumstances, after taking effective measures, the distance may be appropriately reduced.
Explosion-proof electrical retrofitting and on-site explosion-proof construction consulting services for hazardous areas - Shenzhen Zhongnuo Testing Technology Co., Ltd.