What Duct Banks Are
Duct banks are grouped underground conduit systems used to route and protect multiple electrical and communication cables. A duct bank typically consists of several plastic (HDPE/PVC) or concrete-encased ducts laid in a planned arrangement, creating a durable, organized pathway for power feeders and data lines.
In EV charging projects, duct banks are used when you need multiple cable runs across car parks, depots, or public streets — especially when planning for future expansion.
Why Duct Banks Matter for EV Charging
Duct banks reduce civil rework and improve reliability in large or expandable sites:
– Provide protected routes for high-power feeder cables
– Reduce the need for repeated trenching as more chargers are added
– Improve maintainability: easier cable replacement and upgrades
– Support phased rollouts (install ducts now, pull cables later)
– Keep installations tidy and compliant with separation and depth requirements
Where Duct Banks Are Commonly Used
– Fleet depots with many charging bays
– Distribution centres and logistics parks
– Large destination charging sites (retail, hotels, campuses)
– Public curbside or municipal sites with long cable routes
– Sites crossing multiple zones (garage levels, car park islands)
Typical Duct Bank Components
A duct bank system commonly includes:
– Multiple ducts/conduits (often different diameters for power vs comms)
– Spacers to maintain geometry and separation
– Pull ropes and mandrels for commissioning and future pulls
– Marker tape and warning mesh above the ducts
– Access points: pull pits / handholes / manholes at intervals
– Documentation: route maps, depths, as-built drawings
Some duct banks are concrete-encased for extra protection under roads or heavy loads.
Key Design Considerations
Duct banks should be designed around current needs and future growth:
– Number of ducts: include spares for expansion (future bays, higher power)
– Duct diameter: sized for cable OD, pulling tension, and thermal limits
– Bend radius: avoid tight bends that make cable pulling impossible
– Depth and cover: meets local standards and protects from surface loads
– Separation: between LV/MV, power vs comms, and from other utilities
– Drainage and water management: avoid standing water where possible
– Thermal derating: multiple loaded power cables in close proximity can overheat soil/conduits
Common Pitfalls
– No spare ducts → expensive rework later
– Ducts too small or too many bends → cable pull failures
– Missing access pits → impossible to pull long cable runs
– Poor sealing → water ingress, silt build-up, blocked conduits
– Ignoring thermal constraints when many feeders are heavily loaded
– Weak as-built documentation → future expansion becomes risky and slow
How Duct Banks Support Scalable Charging
A common scalable approach is:
– Build duct banks + pits as part of early civil works
– Install a distribution board or switchgear sized for future bays
– Add chargers in phases by pulling new feeder cables through spare ducts
This reduces downtime and total civil cost across multi-year expansions.
Related Terms for Internal Linking
– Directional drilling
– Cable ducting
– Civil works
– Distribution boards
– Cable pulling tension
– Charging bay layout
– Depot charging