Driven Over, Never Seen: How the In-Ground Charger Reclaims Bus Depot Space

UK bus depots were built for diesel. The yards are tight, the bay markings are fixed, and there is rarely a square metre to spare. When operators begin electrification, they face an immediate and practical problem: conventional chargers take up space that buses already occupy.

A standard pedestal charger requires setback clearance, protective bollards, and a dedicated zone around every unit. Multiply that across 40 or 50 bays and the compound effect is significant: reduced vehicle capacity, constrained manoeuvring, and a depot that no longer functions as it was designed to.

The Neutron NSNF0015GRC In-Ground Charger solves this by moving the charging hardware below the surface entirely. The connector sits flush with the tarmac. Buses drive over it. The depot looks and operates exactly as it did before electrification, except every bay is now capable of charging.

How It Works

The NSNF0015GRC is a pit-mounted connector unit, installed flush with the depot surface during groundwork or as part of a planned resurfacing. The top surface is a hardened steel cover rated for the full axle load of a double-deck bus, typically 11.5 tonnes per axle under UK regulations. Vehicles drive over it without restriction.

When a bus parks in the bay, the driver or ground crew connects the charging cable from the pit unit to the vehicle's inlet. The connection point is at ground level, accessible without climbing, reaching overhead, or navigating around any obstacle. Once connected, charging is managed by the Neutron Satellite Terminal serving that bay group.

The physical installation runs from the in-ground unit via a conduit through the pit to the nearest Satellite Terminal. There is no high-voltage equipment at surface level: the NSNF0015GRC carries the DC output cable only. The power electronics sit in the Satellite Terminal, which in turn is fed by the Master Unit.

The NSNF0015GRC installed at a London bus depot. The unit sits level with the tarmac; the yellow Neutron indicator strip is the only surface-level indicator of a charging point beneath.

The Space Mathematics

A conventional 150kW pedestal charger typically requires a 1.5m exclusion zone on each side and protection bollards rated for vehicle impact. In a standard 3.5m bus bay, this constrains the effective parking position and can prevent adjacent bay use during charging activity.

The in-ground charger has zero above-ground footprint. The bay dimensions are unchanged. Drivers park exactly as they always have. Adjacent bays remain fully operational. No bollard installation is required. No signage changes. No zone reconfiguration.

System Integration: Master, Satellite, and In-Ground

The NSNF0015GRC does not operate as a standalone charger. It is the terminal point of a power delivery chain that begins at the Master Unit and passes through the Satellite Terminal. Understanding the architecture is essential to understanding why the in-ground connector can be so compact.

All power conversion from AC to DC happens in the Master Unit, housed in a plant room or external cabinet away from the vehicle bays. The Master connects to one or more Satellite Terminals via DC bus cables, which run overhead or in a dedicated conduit route. Each Satellite Terminal serves a cluster of bays and can support multiple connector types simultaneously, including the NSNF0015GRC in-ground connector, the NSNF0014DDC drop-down connector, and side-mount connectors.

Because the Satellite Terminal handles all the electronics, the in-ground unit itself is entirely passive: a weatherproof housing, a high-current DC cable, and a connector rated for the vehicle charge inlet. There is nothing to service at bay level beyond cable condition checks.

Liquid Cooling and High-Power Operation

Standard in-ground connectors are limited by cable thermal capacity. As charging currents rise toward 350kW and beyond, conventional copper cables become impractically heavy and stiff. Neutron addresses this through an optional liquid-cooled cable upgrade, which circulates coolant through the cable core to manage heat at the rated current level.

Liquid-cooled cables are significantly lighter and more flexible than equivalent air-cooled cables at high amperage, making them easier to connect and less likely to cause connector wear over the system lifetime. The cooling circuit is managed by the Satellite Terminal and requires no separate maintenance infrastructure at the in-ground level.

Future Readiness: HV Direct and MCS

The UK's zero-emission bus transition is accelerating faster than the charging standards that support it. Vehicles entering service today use 400V battery architecture; the next generation of high-capacity electric coaches and double-deckers is moving toward 800V platforms, which require MCS (Megawatt Charging System) compatible infrastructure.

Because the NSNF0015GRC is a passive connector unit, the upgrade path is straightforward. When a depot moves to higher voltage operation via Neutron's HV Direct capability, the in-ground connector hardware is replaced or adapted at bay level; the Master Unit and Satellite Terminal handle the new voltage range without requiring new civil infrastructure. The conduit routes, the pit structure, and the tarmac installation remain in place.

Deployment in Practice

In-ground charger installation is most economical when combined with planned resurfacing or new-build depot construction. The pit structure and conduit routes are installed during groundwork; the connector unit is fitted at tarmac level before the final surface layer is applied. For existing depots, retrofit installation requires core drilling and a localised patch, which can typically be completed bay by bay over consecutive nights without depot downtime.

Neutron provides site survey and conduit routing design as part of the fleet infrastructure engagement. Each installation is modelled for power demand, cable routing, and future expansion capacity before civil works begin.