What are the functions and application locations of explosion-proof wire glands and explosion-proof junction boxes?

Explosion-proof junction boxes, explosion-proof wiring boxes, and explosion-proof conduit boxes are all used for the wiring connections of electrical equipment. They are suitable for explosive gas environments in Zones 1 and 2, as well as for combustible dust environments in Zones 20, 21, and 22, as well as for explosive environments of Classes IIA, IIB, and IIC. Explosion-proof junction boxes can replace explosion-proof wire conduit boxes; wire conduit boxes cannot be considered as junction boxes.

There is a saying that explosion-proof wire glands are only used for running cables through conduit, and cannot be used for running wires through steel pipes. Explosion-proof junction boxes can be used in areas where wiring is required in cable conduits and steel pipe wiring systems for wires. Is the above statement correct? What is the basis?

The literal meaning is clear: an explosion-proof wire passing box is used solely for guiding cables. Its purpose is to facilitate cable passage when the steel pipe is too long, as it is not possible to pass the cables through directly; explosion-proof wire passing boxes are needed at such points to make cable passage easier. Especially at corners, the explosion-proof wire passing box only allows cables to pass through it, without any terminals or wiring facilities available inside； In addition to serving as an explosion-proof wire passing box, the explosion-proof junction box also features wiring terminals inside for connections.

Cannot explosion-proof wire glands be used for routing wires in steel tube wiring systems? In fact, in many production facilities of Class A and B hazardous chemicals enterprises, explosion-proof wire glands are used for connecting the wires at the bends in steel tube wiring systems – does this pose a safety risk? Basis? ? ?

This post was last edited by chb1534 on 2017-9-27 08:14. 1. Clause 9.1.2 of GB3836.15-2000 stipulates: “Unsheathed single-core wires shall not be used as conductive wiring, unless they are installed within distribution panels, enclosures, or conduits.” “ 2. Article 5.4.1.2 of GB50058－2014 stipulates: “In areas with explosion hazards, except in distribution panels, junction boxes, or systems using metal wiring, unshielded wires shall not be used as distribution circuits.” “ 3. The distribution panels, junction boxes, or enclosures mentioned in the previous two points are easy to understand; they refer to explosion-proof products in which wires and metal conduits can be used for the power distribution system. For such systems, one can refer to Article 13.2 of GB3836.2–2010. This article contains many details, so I won’t go into them here. In short, metal conduits must also meet the requirements for explosion protection, and they need to have gasket seals. This approach is widely used in the United States, but it is hardly ever employed in our country. In summary: Wiring using steel pipes with increased-safety type wire glands does not constitute conduit wiring; it is not allowed to use wires (unsheathed single-core wires) within non-conduit wiring.

Upstairs: Therefore, it is not permitted by standards to use wires (unsheathed single-core wires) for internal steel pipe wiring. According to GB50058‑2014 5.4.3 4, steel pipe wiring may use unshielded insulated single-core or multi-core wires. To this end, it is permissible to use wires (unshielded single-core wires) inside the steel pipe wiring (steel pipe).

Clause 5.4.1.2 of GB50058-2014 stipulates that in areas prone to explosions, except within distribution panels, junction boxes, or wiring systems using metal conduits, unshielded wires shall not be used for power distribution circuits. Therefore, the mention in clause 5.4.3.4 of “unshielded insulated single-core or multi-core wires can be used in piping-based wiring systems” refers to the “metal conduit wiring systems” specified in clause 5.4.1.2. In my opinion, unshielded wires are not allowed to be used for wiring if conduit wiring is not employed; however, if the piping-based wiring system meets the requirements outlined in clause 5.4.1.2, then the use of unshielded wires is permitted.

I agree with your conclusion: in explosion-proof areas, unshielded wires should be used for distribution circuits, and wiring must be installed using steel pipes that meet the required standards.

A wire gland is used to facilitate wiring and is placed in the middle of the conduit; a junction box, on the other hand, is a box with wiring terminals – their functions are different

Upstairs: For steel pipe wiring, there are two types – unarmored cables and wires (unsheathed conductors). What I would like to ask is: can wire conduits be used for steel pipe wiring with wires (unsheathed conductors)? (They can definitely be used for steel pipe wiring with unarmored cables.)