Source for the method of cable routing through conduits in explosive hazardous environments
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①I saw a statement in the third edition of the Manual for Industrial and Civil Power Distribution Design stating that in explosive hazard environments, hot-dip galvanized steel pipes should be used for cable conduits. Does anyone know the source of this specification? ②Also, why is a flexible hose required for connecting the power cable at the equipment inlet? Can’t I just run it directly from the cable tray and lay it openly to the equipment for connection without using a flexible hose? Is there a source for the standard?
Your standards seem to be based on older versions; you should check whether they refer to the old standard GB50058-92. The newer standards, GB50058-2014 or GB3836.15-2000, do not require the use of conduits. However, if no conduits are used, the cables must have protective measures similar to those of armored cables.
Galvanized wire conduits are mainly used to shield interference signals (to prevent interference and to avoid being affected by it) as well as to protect cables (from corrosion and to prevent breaks). Moreover, grounding is necessary; therefore, when connecting the threads of the cable conduit, tape should not be used. Additionally, it is possible to run the cables openly up to the equipment, but they should not be run openly through the cable tray; instead, galvanized pipes should be used to carry the cables from the cable tray to near the equipment, where they can then be run openly. In environments with repeated explosions, the cables connecting devices must have a protection rating of at least IP54 to meet the protection requirements of such environments; in addition, there are requirements regarding the tensile strength of these cables, which is why flexible conduit or explosion-proof connectors are necessary. Additionally, ordinary flexible conduit does not meet the required protection level, so an explosion-proof isolation seal box needs to be added. When the conduit is installed from top to bottom, waterproofing also needs to be taken into account.
Procedure: For cables with a diameter of ≤50 mm, select appropriate explosion-proof components to achieve EXDIICT2 certification. After the cable passes through galvanized pipes and flexible pipes, both ends must be sealed with explosion-proof putty to provide explosion isolation. The threaded ends of galvanized pipes must be coated with conductive paste before being joined together. For cables over 70 mm in diameter, cable trays are generally used to hold the exposed wires; explosion-proof disconnect switches and explosion-proof flexible conduits are employed, and the connections are then sealed with explosion-proof putty inside the equipment junction boxes.
You can give it a try if there’s no other option. For example, when using large cables, galvanized steel pipes with a DN100 diameter or larger require bending; the bending radius is too large, resulting in insufficient installation space
Is there a standard source where this IP54 requirement can be found? Thank you
You can refer to this post: http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1641780&page=1#pid16998675