Manhole chambers are underground access structures that provide safe entry and inspection points for buried utilities such as electrical conduits, cable ducts, earthing conductors, and communication lines. In EV charging projects, manhole chambers support serviceable cable routing between main LV panels, feeder pillars, and EV chargers—especially in car parks, streetscapes, and large commercial sites where cables run underground.
What Are Manhole Chambers?
A manhole chamber is a below-ground enclosure (often concrete or polymer) with a removable cover, designed to:
– Provide access to underground ducts and cables for installation and maintenance
– Allow cable pulling, jointing, branching, or inspection at key route points
– Protect utility connections from soil pressure, water ingress, and mechanical damage
Manhole chambers are also used as “pull boxes” or “inspection chambers” depending on size and access method.
Why Manhole Chambers Matter in EV Charging
EV charging networks often require long underground cable runs, multiple feeder routes, and future expansion. Manhole chambers help:
– Reduce installation risk by enabling staged cable pulling over long distances
– Avoid excessive cable pulling tension and bending that can damage insulation
– Provide accessible points for fault finding, repairs, and cable replacement
– Enable future capacity upgrades without cutting asphalt or concrete
– Support clean site layouts by keeping cables concealed and protected
They are especially important in public charging sites, curbside deployments, and large parking facilities.
Typical Uses in EV Charger Installations
– Cable routing from transformer/MDB to an EV charging distribution point
– Branching ducts to multiple chargers or parking rows
– Housing cable joints, terminations, or transition points (duct-to-trench, trench-to-plinth)
– Creating accessible points near chargers for troubleshooting underground faults
– Supporting separation of power and data ducts to reduce interference and simplify servicing
Key Design Considerations
– Location: place chambers where they remain accessible and won’t be blocked by vehicles, landscaping, or permanent structures
– Load class: select covers rated for expected traffic (pedestrian areas vs car parks vs heavy vehicles)
– Drainage and water management: consider groundwater level and use sealed covers or drainage solutions where needed
– Internal space: ensure enough room for cable bend radius and safe working access
– Duct entries: plan spare ducts for future expansion and avoid sharp entry angles
– Safety: ensure covers are secure and prevent unauthorized access in public areas
– Identification: label routes and ducts to simplify maintenance and reduce repair time
Common Problems When Manhole Chambers Are Poorly Planned
– Chambers placed under parking bays or heavy traffic zones without adequate cover rating
– Insufficient chamber size causing tight bends and cable damage
– Lack of pull points forcing destructive works to replace or add cables
– Water accumulation leading to corrosion, insulation degradation, or communication failures
– Missing documentation of duct routes and chamber locations, slowing down fault finding
How Manhole Chambers Reduce Lifecycle Cost
– Faster cable installation and easier commissioning
– Reduced need for cutting and reinstating hard surfaces during repairs
– Improved maintainability and maintenance cost reduction
– Easier site expansion for additional EV chargers or higher power feeders
Related Glossary Terms
Cable ducting
Conduit installation
Cable routing
Pull box
Trenching
Main LV panels
Feeder circuit
Maintenance access planning
Voltage drop
Earthing and bonding