【Weekend Share-9】Do stainless steel and aluminum alloy cable trays need to be bridged?

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This post was last edited by zhoudingshengs on 2024-12-14 at 11:43. 1. Do stainless steel and aluminum alloy cable trays need to be bridged? 【Answer】There are discrepancies among the norms in different fields. For municipal wastewater treatment plants, it is not necessary to connect grounding wires across both ends of the connection plates for galvanized, stainless steel, and aluminum alloy tray systems. In the petrochemical industry, stainless steel and aluminum alloy cable trays require bonding wires. 【Basis】 I. Article 9.7.1 of GB50334-2017 \"Code for Quality Acceptance of Urban Sewage Treatment Plant Projects\": The grounding of metal cable trays and supports, as well as the metal cable conduits that lead in or out, must be reliable and must comply with the following provisions: 1. The metal cable trays and their supports shall be connected to the main grounding wire at no fewer than 2 points along their entire length ； 2. At both ends of the connection plates between metal cable trays, other than those made of galvanized steel, stainless steel, or aluminum alloy, tin-plated copper core grounding wires should be used; the allowable cross-sectional area of such grounding wires shall not be less than 4 mm2 ； 3. When no grounding wire is used to bridge the two ends of the connection plate between galvanized, stainless steel, or aluminum alloy cable trays, anti-loosening nuts or anti-loosening washers should be installed on the connection bolts at both ends of the plate, with a minimum of 2 such bolts. II. SH/T 3569-2020 Specification for Construction and Acceptance of Petrochemical Cable Trays 8.2 Metal Trays 8.2.1 Metal cable trays shall have reliable electrical connections and be grounded. 8.2.2 Both the starting and ending ends of metal cable trays shall be reliably grounded; when the total length exceeds 30 m, additional grounding points shall be installed every 20 m to 30 m. 8.2.3 The ends of the connection plates between galvanized cable trays need not be grounded with jumpers, but each end of the connection plate shall have no less than 2 connection bolts equipped with lock nuts or lock washers. 8.2.4 At the connections of cable trays made of stainless steel and aluminum alloy, dedicated grounding bolt holes shall be used for grounding jumps; the bolt holes provided by the tray connection plates shall not be used for this purpose. The cross-sectional area of the jumper wires shall meet the requirements specified in the design documents. 8.2.5 When the cable tray surface has an insulating coating, the insulating layer at the areas where electrical connections are required must be removed completely.