Industry News

   On construction sites, it's common to see cables of various lengths—ten meters, twenty meters, or even around a hundred meters—left by the roadside. These are leftover cables from installation projects. Typically, site managers sell these remnants as scrap, despite the cables originally being high-value products. Selling them at scrap prices results in significant waste and increases project costs. Therefore, we need to consider how to minimize cable waste while ensuring construction quality, thereby maximizing resource utilization and reducing project costs—a shared goal and expectation for all construction companies.

I. Preparations Before Cable Installation

Before installation, the following preparatory work should be completed:

1. Cable Inspection:
   Verify that the cable model and specifications meet design requirements. Check whether the cable reels and protective layers are intact, and ensure both ends of the cable are free from moisture.

2. Site Condition Assessment:
   Inspect the depth of cable trenches and the distances between cables and other pipelines (whether crossing or parallel) to ensure they comply with relevant regulations. Confirm that all obstructions have been cleared.

3. Determining Installation Method and Reel Placement:
   Plan the cable installation method and the positioning of cable reels. During manual installation of directly buried cables, organize personnel properly to control the installation speed and avoid damage caused by excessively small bending radii. When installing cables on cable trench or tunnel brackets, pre-arrange the cable positions and the sequence of installation to prevent交叉 and ensure the cables have room for expansion and contraction. For mechanical pulling, take care to prevent friction and compression damage at bends and corners of the trench.

II. Economic Analysis of the Cable Installation Process

1. Accurate Cable List Preparation:
   A major cause of excessive cable waste is that construction managers often fail to thoroughly understand design drawings or are unfamiliar with actual site conditions. Blindly copying design documents to tally cable models and lengths can lead to significant discrepancies between design lengths and actual needs, or mismatches between cable models and equipment requirements.
   To address this, a structured form can be designed. When filling out this form, managers must first familiarize themselves with the electrical construction plan and system diagrams, clarifying the routing of each cable as per the drawings. Fill out the form cable-by-cable based on the outgoing lines of the low-voltage distribution system. This approach helps avoid omissions and errors, and allows for early detection of design inconsistencies—such as mismatches between plan and system diagram cable models/sizes, or discrepancies between motor capacity and designed cable load.
   Given that projects may involve dozens of cable types and thousands of cable runs, plus design changes across disciplines, errors are inevitable. However, these design flaws shouldn't excuse inadequate cable list preparation. Especially during the preparation phase, managers must fully account for cable lengths not explicitly shown in design drawings.

2. Cable Length Calculation:
   Use the following formula:
   Cable Length = Drawing Length + Cable Slack Length + Cable Terminal Length + Cable Entry Length (to Panel/Motor) + Bend Allowance

• Cable Slack: 2.5% of total cable length

• Cable Terminal Length: 1.5m

• Cable Entry Length: For panels, use the semi-perimeter (width + height); for motors, 0.5m

• Bend Allowance: 15D (D = cable diameter). Calculation: Drawing Length - 2 × 15D + 2 × π × 15D × 0.25
  After calculating cable lengths using this formula, input the verified cable models and design lengths into an Excel spreadsheet for future statistics and comparison.

3. Utilizing Excel for Cable Matching (Handling Design Changes):
   Once cable trays, distribution panels, and equipment are installed on-site, managers should:

• Verify that the power ratings on equipment nameplates match the design drawings and ensure the designed cable models are suitable.

• Create cable tray layout diagrams based on drawings and actual cable routing. These diagrams serve both as guides for cable placement and as the basis for calculating actual cable lengths according to site conditions.

• Check whether the drawn cable routes match the actual routes. If not, recalculate cable lengths using the formula based on the actual routing.

III. Key Considerations During Cable Installation

During cable installation, pay attention to the following:

1. Training Installation Workers:
   Proper training for cable installation workers is crucial.

2. Personnel Planning:
   Divide installation personnel into several teams to work simultaneously, accelerating the installation progress where possible.

3. Accuracy and Aesthetics:
   The quality of cable installation depends on process control, not post-installation corrections. Install cables according to verified drawings and work instructions, checking each cable as it is laid to ensure accuracy.

With evolving times, we all recognize the importance of conserving resources. This approach not only reduces project costs but also responds to the national call for energy conservation—making resource savings efficient and optimal!