--- title: "Criteria for distribution line route selection" subject: "Transmission and Distribution System Design" chapter: 7 key: "semester_8/transmission_and_distribution_system_design:distribution-route-selection-criteria" source: https://www.bctengineer.com/q/semester_8/transmission_and_distribution_system_design/distribution-route-selection-criteria site: BCT Engineering --- # Criteria for distribution line route selection Transmission and Distribution System Design · Chapter 7: Distribution System Design - Asked in: 2078 Chaitra, 6 marks; 2069 Bhadra (old course), 6 marks; 2067 Mangsir (old course), 6 marks (asked 3 times) - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_8/transmission_and_distribution_system_design/distribution-route-selection-criteria - Whole chapter: https://www.bctengineer.com/md/semester_8/transmission_and_distribution_system_design/chapter-7 ## Question Describe the general criterion that should be taken into consideration for distribution (LT) line route selection in a distribution system. ## Short answer Choose the shortest practical route along roads near load clusters, with easy access and maintenance. Prefer public land, avoid unsafe terrain and crossings, maintain clearances, and allow future expansion. Final route is fixed after walk-over survey considering cost, technical limits and community views. ## Answer The **route** of an LT (and HT) distribution line is the path along which poles are erected. A good route gives the shortest, safest and cheapest line that serves the consumers well and is easy to maintain. #### General criteria 1. **Shortest practical length:** a route close to a straight line between the transformer and load clusters reduces cost, voltage drop and losses. Avoid unnecessary bends, since each angle point needs a stronger pole with stays. 2. **Follow roads and tracks:** lines along the road side (within the road right-of-way) give easy access for construction, operation and maintenance, and avoid crossing private land. 3. **Proximity to consumers:** the line should pass near the houses to keep service drops short (typically within about 30–40 m), reducing service cable cost and losses. 4. **Load balance:** arrange feeders so that load is shared equally among phases and feeders, and so the transformer remains near the load centre. 5. **Right-of-way and land issues:** prefer public land; minimise compensation, disputes and tree cutting. Avoid passing over buildings. 6. **Safety clearances:** maintain statutory clearances from buildings, roads, footpaths, telecom lines and other power lines (as per Nepal Electricity Regulations); avoid schools, playgrounds and fuel stations. 7. **Terrain and soil:** avoid landslide-prone slopes, river banks, flood plains, marshy and unstable ground; choose firm ground for pole foundations. 8. **Crossings:** minimise crossings of rivers, highways, railways and other lines; cross at right angles where needed. 9. **Environment and aesthetics:** avoid forests, heritage sites and protected areas; use ABC or underground cable in sensitive or crowded areas. 10. **Future expansion:** leave room for new consumers and for future upgrading (e.g. to three-phase or larger conductors). 11. **Span and pole positions:** keep uniform spans (about 40–50 m for LT) and place poles where they will not obstruct traffic or drainage. The final route is fixed after a walk-over survey, considering cost, technical limits and the views of the local community. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Why should an LT line route be as straight and short as practical? A. To increase voltage drop B. To reduce cost, voltage drop and losses, and avoid angle poles needing stays C. To use more poles D. To lengthen service drops Answer: B. Shorter route means less conductor, lower drop and loss, and fewer costly angle points. (Key point: Shortest route) 2. Why follow roads and tracks? A. To avoid safety clearances B. Easy access for construction and maintenance, and no private land crossing C. To cross rivers D. To increase span Answer: B. Road-side routes ease operation and maintenance and avoid land disputes. (Key point: Following roads) 3. Which ground should the route avoid? A. Firm ground B. Road sides C. Landslide-prone slopes, river banks and marshy ground D. Public land Answer: C. Unstable ground endangers pole foundations; choose firm ground. (Key point: Terrain) 4. Why should the line pass near houses? A. To keep service drops short (about 30-40 m), reducing cost and losses B. To raise voltage C. To avoid transformers D. To increase span length Answer: A. Short service cables cost less and lose less. 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