1. Cable tray selection and installation standards
Cable tray installation is based on GB 50303-2015 and CECS 31:2006. Cable tray type selection: fully enclosed trough-type cable trays are suitable for weak-current systems without electromagnetic interference requirements; perforated-bottom tray-type cable trays are suitable for power cables with high heat dissipation requirements; rung-type cable trays are suitable for large cross-section cables. Material specifications: hot-dip galvanized steel sheet with a zinc coating of not less than 65 microns, or aluminum alloy profiles with thickness not less than 1.5 mm when width is not more than 400 mm, or not less than 2.0 mm when width is more than 400 mm.
2. Cable tray grounding and equipotential bonding
Cable tray grounding is a core step in ensuring electrical safety. Requirements are based on GB 50303-2015 and GB 50057-2010: metal cable trays shall be reliably connected to the grounding main line at not fewer than 2 points along their entire length; dedicated grounding jumpers of not less than 4 sqmm copper braid or not less than 10 sqmm BV wire shall be used between cable tray sections; grounding shall be provided at both the starting end and the terminal end of the cable tray; the grounding main line shall use 40 mm x 4 mm galvanized flat steel or copper conductor of not less than 25 sqmm.
3. Firestop sealing construction technology
Firestop sealing of openings in fire walls and floor slabs is key to preventing fire spread. According to the requirements of GB 50016-2014 and GA 161-2007: firestop sealing must be provided where cable trays penetrate fire walls and floor slabs; sealing materials shall be flexible organic sealing compound (firestop putty) plus firestop sealing board plus inorganic firestop sealing material (firestop pillows); construction steps: remove debris, install firestop partition boards, fill with firestop pillows, seal with firestop putty, and smooth the surface; sealing thickness shall be not less than 240 mm for fire walls or not less than 150 mm for floor slabs.
4. Cable tray installation acceptance and quality inspection
Cable tray installation acceptance is based on GB 50303-2015 and GB 50168-2018. Inspection items: appearance inspection to confirm the galvanized coating is not damaged, the coating has not peeled off, and the cable tray is not deformed; support spacing inspection using a tape measure, with deviation not more than plus or minus 50 mm; horizontality and verticality inspection, with horizontal cable tray deviation not more than 5 mm/m and not more than 10 mm over the full length, and vertical cable tray deviation not more than 5 mm/m and not more than 20 mm over the full length; grounding resistance test using a grounding resistance tester, not more than 4 ohms; firestop sealing inspection to confirm materials are qualified, thickness meets the standard, and sealing is tight.