When the cable tray is allowed to form the grounding trunk circuit, the cable tray and its support and hanger connection plate shall be able to accept the grounding fault current and meet the requirements of thermal effect. As the grounding trunk, the connection resistance between the increased price end of the tray shall be greater than 0.00033 Ω. When the cable tray is used as the grounding trunk, all kinds of expansion joints and soft joints of the cable tray shall be made of copper The cross section of flexible conductor or woven copper wire shall not be less than 16mm2.
The whole cable bridge shall be laid with grounding main line independently. When flat steel is used for grounding main line, the cross section shall not be less than 60m m2 for indoor laying and 10m m2 for outdoor laying. When the bridge is introduced into or led out of the building, it shall be connected with the indoor grounding main line or outdoor grounding equipment of the building.
In order to avoid the effect of electrochemical corrosion, the bare copper track shall not be used as the grounding main line on the aluminum alloy cable tray, the cable tray shall not be used as the sidewalk ladder or standing channel, and its support and hanger shall not be used as the support for hanging heavy objects. When the cable is corroded in the cable tray, the support and hanger of the cable tray shall not be used as the fixed lifting equipment, the dragging equipment, pulley and support.
When there is insulation coating on the surface of the cable tray, the insulation coating at the grounding address or the required electrical connection shall be removed and cleaned, and the connection bolts of the cable tray at the oscillation place and the electrical grounding part shall be equipped with spring washer.
For the aluminum alloy cable tray with the equipment on the steel hanger or fixed with steel accessories, when the surface of the steel parts is hot-dip galvanized, it can be directly touched with the aluminum alloy cable tray. When the surface of the steel parts is sprayed with powder coating or painting, it should be blocked with polychloroethylene or chloroprene rubber gasket between the contact surfaces of the aluminum alloy cable tray.