Cable-tray support and hanger mass calculation and norm charging: count positions by spacing, unit mass from section-steel theoretical mass; Beijing 2024 "tray installation includes support installation; support fabrication listed separately per kg"

Topic Positioning

The complete algorithm and charging caliber for cable-tray supports from "spacing layout -> positions -> mass -> norm items", answering "when does the norm include supports and when are they charged separately".

Core Conclusions

1. Layout to positions: where design is silent, supports are spaced 1.5-3.0m horizontally and <= 2m vertically, with fixing points 0.3-0.5m from branches/ends (GB 50303-2015, 11.2.3); support points within 500mm of box/panel entries, corners, bends, and both ends of expansion joints and the three ends of T-joints (DB11/T 1832.17-2021, 9.4.2). Do not just divide straight runs — add points at ends, branches, bends, and entries; fix "positions", then multiply by unit mass. 2. Mass calculation: W = sum(Li x wi), Li single length (m), wi theoretical mass (kg/m).

• Round rods/hangers: w = 0.00617 x d2 (d in mm); φ10 = 0.617 kg/m;
• Flats/plates: w = 0.00785 x b x t (b, t in mm);
• Angles/channels: from theoretical-mass tables or 0.00785 x section area.
• Example (30m run at 1.5m spacing incl. ends): positions = 30/1.5 + 1 = 21; L50x5 angle arm 0.8m x 3.770 = 3.016 kg; two φ10 rods 2 x 0.6m x 0.617 = 0.74 kg; 3.756 kg per position; total approx. 78.88 kg — priced per kg under the fabrication item. 3. Norm charging (Beijing DB11/T 2382-2024):

1. Included, not relisted: tray installation items (C4-11 series, e.g., C4-11-253 steel tray) work content "assembling, installing, fixing, bends, tees/crosses, covers, dividers, accessories and support/hanger installation, earthing, etc." — support/hanger placement and fixing are included; no section-steel main material in the consumption.
2. Charged separately: support fabrication is not in the tray items — per kg under Table C.4.117-1 "metal support fabrication/installation" (e.g., C4-13-1, C4-13-2), work "straightening, marking, cutting, drilling, assembling, welding, painting, embedding, etc.", section-steel main material in the fabrication item; painting already included — do not re-charge.
3. General comparison: GB/T 50856-2024, 3.0.10 — equipment, pipe, and accessory installation items include support/hanger/foundation-channel fabrication, installation, and painting; where specially designed, itemize under Annex N or Annex M. Final charging follows the contracted basis (measurement standard or local consumption standard) item work contents.

Applicable Boundaries

• The norm conclusions target Beijing 2024; other provinces follow their current norms' work contents and rules (the "installation included / fabrication separate" split may differ — check item work contents first).
• Mass formulas and the example are generic: dimensions per drawings and approved technical documents; spacings are defaults where design is silent — design governs.
• Tray items include "support/hanger installation"; factory supports priced separately per the applicable basis — do not mix with site-fabrication calibers.

Further Reading

• DB11/T 2382-2024 Annex C: Table C.4.93-1.2 steel trays (C4-11-253 etc.), Table C.4.117-1 metal supports (C4-13-1/2).
• GB/T 50856-2024, 3.0.10, Annexes N and M.
• Layout: GB 50303-2015, 11.2.3; DB11/T 1832.17-2021, 9.4.2.