What is a Shore Supply in railways?

Shore Supply is an external power source used in railway depots to provide electricity to parked trains. It allows auxiliary systems like lights, HVAC, and battery chargers to run without using the high-voltage overhead catenary or running diesel engines.

What voltage is used for railway Shore Supply?

The voltage depends on the train type, but common standards include 400V AC (3-phase) for auxiliary loads, or DC voltages (like 750V DC) delivered via stinger systems for specific metro or light rail maintenance operations.

What is the difference between a Stinger System and a Plug connection?

A Plug connection uses a cable inserted into a socket on the train's underframe to power auxiliary systems. A Stinger System is typically a retractable overhead drop-cable or trolley that contacts the train's power collector, often used to move trains in depots or power DC traction systems.

Power in the Depot: Shore Supply Systems Explained

Keep trains powered safely during maintenance. Learn how Shore Supply systems provide auxiliary power to rolling stock in depots without using live overhead lines.

December 10, 2025 7:40 am

Shore Supply, also known as a Depot Feeding System or External Power Supply, is a critical infrastructure component in railway depots and workshops. It allows rolling stock (trains) to be powered up for cleaning, maintenance, and testing while the main traction power (Overhead Catenary or Third Rail) is switched off or disconnected.

Why is Shore Supply Necessary?

When a train enters a maintenance hall, the high-voltage overhead lines are often de-energized and grounded to allow staff to work safely, particularly on the roof. However, the train still requires electricity to operate its auxiliary systems.

Battery Charging: Keeping the train’s batteries from discharging during long maintenance intervals.
HVAC Testing: Running heating, ventilation, and air conditioning systems for diagnostics.
Lighting & Doors: Providing visibility and access for cleaning crews inside the carriages.
Software Updates: Powering on-board computers without running diesel engines or activating high-voltage circuits.

Comparison: Shore Supply vs. Traction Power

Shore supplies differ significantly from the standard power used to move the train. They are designed for stationary loads rather than propulsion.

Feature	Traction Power (OCS/Third Rail)	Shore Supply (Depot Power)
Primary Purpose	Propulsion (Moving the train)	Auxiliary Services (Stationary)
Voltage Levels	High (e.g., 25kV AC, 1500V DC)	Lower (e.g., 400V AC, 3-Phase)
Connection Method	Pantograph or Collector Shoe	Manual Plug or Stinger System
Safety	Hazardous for maintenance access	Safe for personnel (with interlocks)

Types of Connections

There are two common methods for delivering shore power to the train:

1. Plug and Socket (Umbilical)

Similar to plugging in an electric vehicle, a heavy-duty cable is manually connected to a specific socket on the train underframe. This usually supplies standard industrial voltage (e.g., 3x400V) to the train’s auxiliary bus.

2. Stinger System (Retractable Overhead)

In DC traction systems (like Metros), a “Stinger” is a retractable trolley or overhead drop-cable that connects directly to the train’s collector area. This is often used to move trains slowly within the depot without energizing the entire third rail or catenary.

Safety and Interlocking

Safety is paramount when using shore supplies. Advanced Interlocking Systems are installed to prevent accidents. For example, the train’s traction package is physically disabled while the shore supply is connected, preventing the train from driving away and ripping the cable out. Conversely, the shore supply socket often cannot be energized until it is fully mated with the train, preventing electric arcs.