In the electrical design and construction of buildings, it is clear that the cable tray should be grounded, but should the support of the cable tray also be grounded? What is the grounding standard of cable tray? Now let Jinan cable bridge manufacturer give you a brief analysis!
The grounding of the cable bridge we mentioned more clearly refers to the connection between the cable bridge and the protective conductor. Its purpose is to ensure that the grounding fault current can return to the neutral point of the transformer through the protective conductor (PE line) when the insulation of the cable inside the bridge is damaged and the phase line is in contact with the bridge (single-phase grounding fault occurs), so that the protective apparatus of the cable circuit with the insulation damage can remove the grounding fault in time, Therefore, the cable bridge needs to be grounded.
During construction, the following measures must be taken to ensure the safe grounding of cable tray:
(1) Be familiar with the setting and connection position of grounding main line, as well as the selection of grounding main line section and jumper grounding wire section in the construction design document.
(2) The grounding point can be reserved and led out at the electrical embedding stage to meet the grounding requirements at the beginning, end and middle of the cable tray. The material and section of grounding main line shall meet the design requirements. If there is no requirement in the design, the section can be selected according to the provisions of the section of the protective conductor (PE line conductor) in the Acceptance Code. When the grounding main line adopts section steel (such as flat steel or round steel), its section shall meet the design requirements or be converted according to the corresponding conductivity value.
(3) The jumper grounding wire shall be copper core flexible wire or tinned copper braided wire, instead of single stranded copper core wire, and its section shall meet the design requirements. When there is no requirement in the design, the allowable cross section of jumper wire shall be no less than 4 mm2 (copper) and no more than 25 mm2 (copper).
(4) The special grounding bolt welded on the cable bridge body should be used as the connection point of the jumper grounding wire, and the connecting plate connecting bolt should not be used as the connection point of the jumper grounding wire; If the product is not equipped with a special grounding bolt, and the bolt of the connecting plate is used for the jumper grounding connection during construction, the non-conductive coating at the jumper grounding connection shall be treated to ensure the reliable electrical connection of the jumper grounding wire.
(5) The jumper grounding wire between each section of cable bridge can be used for jumper connection, or a copper bar or copper core wire or galvanized steel (flat steel or round steel) can be laid along the full length of the cable bridge as the grounding main line. Each section of cable bridge (including straight-through, bend-through, etc.) should have at least one reliable connection with it. The connecting bolts at the connection should be equipped with spring washers to ensure that the connection is tight and reliable.
(6) Galvanized cable tray can be bridged by its galvanized connection plate instead of jumper wire, but the two ends of the connection plate shall be connected and fixed by not less than 2 bolts with locking nuts or washers to avoid loosening and disconnection of the connection and ensure reliable connection of the jumper grounding.
(7) The support, bracket and hanger shall be reliably connected and grounded with the cable tray, and can be connected with a copper bar or copper core wire or galvanized flat steel laid along the full length of the cable tray as the grounding wire of PE line, or can be connected with the existing grounding cable tray by jumper connection, such as copper core flexible wire or tinned copper braided wire, or at least 2 places can be connected and fixed with the cable tray by claw nut, Make it form a reliable electrical connection with the cable tray.
We have answered the above questions again. If you have any doubts about this, please come to our website at any time Consult and understand!