Why proper cable routing matters
Cable installation is the most labor-intensive electrical work phase. It affects not just system operability but safety, maintainability, and cost of future upgrades.
Rule 1: Minimum bend radii
- Copper ≤10 mm²: R ≥ 6D
- Copper >10 mm²: R ≥ 10D
- Aluminum: R ≥ 15D
Rule 2: No concealed wiring without as-built drawing
Any chased or conduit route must be on the plan.
Rule 3: Load-bearing wall chasing
Max 25 mm depth, 3 m length horizontal. Max 50 mm vertical. Better to route through partitions.
Rule 4: 30% conduit reserve
Fill factor max 0.4-0.5. Always leave 30% free for future.
Rule 5: Cable labeling
Each cable labeled at both ends: group number, purpose, cross-section.
Rule 6: Segregation
Power and data cables — separate trays or metallic divider. 200 mm gap for unshielded, 50 mm for FTP/STP.
Rule 7: Distance from heating pipes
Min 200 mm from hot pipes (>60°C), 100 mm from cold pipes.
Rule 8: Fire-resistant cables for escape routes
FP cables must maintain function for 180 min (BS 5839, VDE 0108).
Rule 9: Outlet heights
Residential: 300 mm AFF. Kitchen (work zone): 100-150 mm above counter. Switches: 900 mm AFF.
Rule 10: Pre-screed check
Test all cables for continuity and IR (>0.5 MΩ). Photo-document routes with a tape measure.
Rule 11: Outdoor temperature rating
Cable must withstand -40°C to +40°C. Arctic-grade insulation needed.
Rule 12: Expansion loops
Every 30 m in rigid-mounted tray or direct burial runs.