Charging Infrastructure > Planning and Design Standards

1. Fleet

2. Depot

3. Charging Infrastructure

4. Operating Environment

Planning and Design Standards

The planning and design of e-bus charging infrastructure must be based on fleet characteristics, charging demand, site conditions, and long-term operational requirements, while ensuring electrical, thermal, water, cyber, and structural safety as explained in detailed in the following sections. These recommendations outline an integrated approach aligned with national and international standards to ensure safe, resilient, interoperable, and future-ready charging systems that support reliable depot operations, grid stability, and emergency preparedness.

QnA

Q1. An STU is commissioning a new depot with multiple fast chargers. Before charging begins, operators are instructed to ensure the e-bus has completed operations and is safely prepared for charging. Which requirement directly supports electrical and thermal safety during this transition?

Immediate connection of the charger after bus arrival Maintaining a pre-charging time gap with the bus in park mode and ignition off Allowing charging while the bus remains in drive mode Reducing earthing resistance below 5 ohms

Q2. During peak summer operations, a depot observes repeated alerts related to elevated battery temperatures during charging. Which pre-disaster thermal safety measure most effectively mitigates the risk of battery overheating and thermal runaway?

Increasing charging current to reduce charging duration Disabling battery temperature alarms to avoid nuisance alerts Ensuring adequate ventilation and active cooling in battery and charging areas Parking e-buses closer together to reduce ambient heat exposure

Q3. During depot design in a flood-prone area, engineers are deciding how to position charging equipment and electrical panels. Which measure best ensures flood resilience of charging infrastructure?

Installing chargers at ground level with drainage channels Routing high-voltage cables through low-lying trenches Elevating chargers and electrical equipment above historic flood levels Using open cable trays for faster water drainage

Q4. An STU wants to ensure that its charging infrastructure remains interoperable, secure, and compatible with future systems. Which requirement best supports cybersecurity and long-term interoperability?

Proprietary charging protocols with closed networks Manual authentication for charger access Adoption of OCPP 2.0.1 or higher with TLS encryption Direct internet connectivity for all chargers

ELECTRICAL SAFETY

Planning Recommendations

Effective implementation of electrical safety requires targeted mitigation actions by relevant stakeholder, as outlined in the following table to support enforcement and ensure compliance.

S.No.

Activities

Responsibility

Site Condition Assessment

Accessible Distribution Systems

Transformer Earthing Connections

Medium Voltage – Low Voltage Integration:

Establish safe boundaries to minimise risk of electrical injuries

Compact Switchgear Design

Maintain physical segregation between electrical components

High Voltage Area Identification

Pre-Charging Time Gap in e-bus

10.

Time Gap between charging Sessions

11.

Charging Status Confirmation

Following finalisation of e-bus specification, fleet size in the depot/ terminal and charging requirement, the public bus agencies or depot operator in consultation with Charger OEMs or Bus OEMs, shall determine the required number, type, rating of charging equipment and associated infrastructure. Based on the charger ratings and total number of chargers, the connected electrical load shall be assessed and submitted to the DISCOM, which shall be responsible for planning, approving, and provisioning the requisite upstream electrical infrastructure, including transformers and substations. Other aspects for consideration for safe and efficient operation of the charging system are brought out herein:

Site Condition Assessment: Following evaluation of depot/ terminal site characteristics such as low-lying area prone to floods, seismic zone, extreme temperature and dusty environmental conditions besides other characteristics, plan for charger pedestal height, adequate provision for flood resilient cable ducting and connectors of charging stations; shed of appropriate height and width for adequate ventilation and to protect not only the chargers from weathering effects but also the bus charging connection points when connected to chargers.
Accessible Distribution Systems: All distribution methods to remain accessible and undergo regular inspection and maintenance.
Transformer Earthing Connections: Connect the transformer cabinet, bracket, foundation section steel and the casing separately and reliably with protective conductor with the help of complete fasteners and anti- loosening parts.
Medium Voltage – Low Voltage Integration: Connect the medium and low voltage distribution systems using sectional unit bus configurations.
Compact Switchgear Design: Provide a Switchgear that is compact and oil-free and designed for minimal maintenance or maintenance-free operation.
Maintain physical segregation between electrical components:
- Low Voltage (LV) and High Voltage (HV) panels
- Charging bays and control electronics
- Operator access zones and live terminals
High Voltage Area Identification: Use color-coded conduits, warning signage, and barriers to clearly demarcate HV areas.
Pre-Charging Time Gap in e-bus: Ensure that the necessary time interval (e.g.5-10 mins), between completion of e-bus operation and commencement of bus charging, is provided before the bus is taken up for charging and that the bus is in “park mode” before charging, with the parking brake engaged and the ignition off.
Time Gap between charging Sessions: Maintain a 5–10-minute cooling period between charging sessions.
Charging Status Confirmation: A “Charger Connected” message shall appear on the instrument cluster, confirming a secure connection and charging initiation.

Design Standards

Following communication of the connected load requirement, sire details and charger specification (type, rating, quantity and related parameters) to the DISCOM, the planning, design and provisioning of the sub-station, transformers, switch gears and associated upstream electrical infrastructure shall be the responsibility of the DISCOM. The downstream electrical connections from the DISCOM transformer up to the charging equipment within the depot/terminal shall be undertaken by the public bus agencies in close coordination with the DISCOM. On the depot/terminal side, the charging system shall comply with the applicable standards outlined below, among others.

Follow the local building codes and safety standards for materials used and the installation of charging stations procedures.
EV Conductive Charging System – General aspects: International standards: IEC 61851-21:2001, and IEC 61851-1:2001.BIS Standards – IS 17017 and IS 15118 together form the foundation of electric vehicle (EV) charging ecosystem, ensuring a safe, interoperable, and future-ready infrastructure. By harmonising hardware (IS 17017) and communication (IS 15118), a robust, user-friendly, and sustainable EV charging ecosystem, which supports mass EV adoption and integrates with the evolving energy grid, is created.
Inductive charging system Standards:
- Standards and specifications for equipment required for the wireless transfer of electrical energy from the power grid to electric road vehicles: IEC 61980
- Safety and interoperability requirements for on-board equipment enabling wireless transfer of magnetic field energy for charging electric vehicles: ISO 19363
- Recommended practices on electric vehicle inductively coupled charging: SAE J1773
Safety related warning labelling practice on components, sub-systems, and systems – Contents, placements, and durability through-out product life cycle i.e., initial use to disposal at End of Life (EOL): SAE J 2936 2025.
Conduct the high and low voltage transformers with non-combustible materials, meeting safety requirement and having enclosures with a minimum ingress protection rating. General standards: IS 2026 & IEC 60076.
In transformer and distribution system, use Copper core, XLPE insulation, and flame-retardant cable with optimized routing and proper installation for safety and reliability.
Apply protective measures where cables are exposed to mechanical stress, vibration, moisture, or corrosive substances.
Distribution boxes to comply with electrical safety standards to prevent electric shock.
For special power transformers, use metal or insulated-sheathed cables, buried, and routed through steel conduits to ensure lightning protection.
Install surge protection devices and lightning arrestors and maintained to prevent damage during electrical storms.
Maintain earth resistance <1 ohm for all exposed and conductive equipment. Ensure equipotential bonding across charger cabinets, dispensers, distribution panels, and nearby metallic structures.
Integrate electrical infrastructure with city disaster response systems for proactive shutdown.
Equip chargers to detect faults and system failures-
- Ground fault detection
- Overcurrent protection
- Overheating protection
- Emergency shutoff switches
Install mandatory protection devices on all circuits and charging station:
- Residual Current Devices (RCDs) rated ≤30 mA
- Overcurrent Protection Devices (OCPDs)
- Surge Protection Devices (SPDs) compliant with IEC 609473.
Age of the charging infrastructure needs to be at par with life of the e-buses.
Provide power quality meter (PQM), with readings monitored by both e-bus operator and electric utility engineer, for EVSE installation above 50kW.
Suspend the charging operations and turn off the power to all the EVSEs in the event of lightning and thunder.
Develop a standard operating procedure (SoP) for maintenance and safe operations of charging infrastructure, guiding the staff on daily activities and safety protocols.

Standard Recommendation

All chargers shall comply: IS 17017, IEC 61851, IEC 60364, IEC 62196, and IEEE 519 standards.
EV Conductive Charging System (AC / DC): Indian Standards: AIS138- part 1 & Part 2; International Standards.: IEC 61851 – 1:2001/21:2001 /22 / 23 & Ministry of Power Guidelines – system design and equipment installation aspects of conductive charging infrastructure
Charging Process Regulation: IEC 61851-23, IEC 61851-24 along with their derivate EN standards
EV Charging Ecosystem: BIS Standards- IS17017 (Harmonising Hardware) and IS15118 (Communication)
High Level Communication via Power Line Communication: Vehicles and the chargers: EN ISO 15118-3 for cabling, Control Pilot contact pin IEC 61851-23 (for vehicles) and IEC 61851-24 (for chargers)
Earthing Connection for Charging Infrastructure: IEC 60364-54

THERMAL SAFETY

Planning Recommendations

Successful thermal safety implementation depends on targeted mitigation measures by relevant stakeholders, as detailed in the table below to enable effective enforcement and compliance.

S.No.

Activities

Responsibility

Charger Heat Protection

Adequate Ventilation Provision

Ambient Temperature Compliance

Thermal Sensor Installation

Fire Detection Systems

Optimised Charging Schedule

Temperature-Tolerant Chargers

Charger Heat Protection: To ensure charger longevity, install roof canopies or shade covers, and where feasible incorporate green roofs or natural vegetation within the site to reduce micro-climate temperature. Additionally, use heat-resistant housing/enclosures and integrate active or passive ventilation systems to minimize heat exposure.
Adequate Ventilation Provision: Provide adequate ventilation around the charging stations and ensure temperature control, especially in indoor charging installations, to maintain proper airflow, prevent heat buildup, and support the optimal ambient conditions required for safe and efficient battery charging.
Ambient Temperature Compliance: The ambient temperature of charging station as specified by OEM shall meet the requirement of normal charging for electric vehicle battery.
Thermal Sensor Installation: Install thermal sensors inside charger cabinets for early warning.
Fire Detection Systems: Install early-warning smoke, gas, heat, and flame detection systems for fire safety.
Optimised Charging Schedule: Schedule charging at night/early morning to minimise thermal stress on charging equipment.
Temperature-Tolerant Chargers: Use temperature-tolerant charger models.

Design Standards

Equip the charging area with fire-fighting equipment such as automatic fire suppression system along with manual fire extinguisher and ensure all staff are trained in its use and safety communication protocols.
As an initiative-taking measure, install Infrared and thermal imaging technologies in detecting temperature anomalies. When integrated with building automation systems, they enable real-time monitoring and early detection of potential fire risks.
Provide remote/automatic shut-off and sectional isolation options in the operator’s control room and near switchgear in case of smoke/heat.

WATER PROTECTION

Planning Recommendations

Ensuring water protection requires clearly defined mitigation actions by responsible stakeholders, as outlined in the table below to facilitate enforcement and ensure compliance.

S.No.

Activities

Responsibility

Elevated Control Rooms

Remote Isolation Systems

Site Grading Measures

Cable Trench Depth

High-Voltage Cable Routing

Flood-Safe Charger Siting

Elevated Electrical Equipment

Weather Shielding Measures

Humidity Control Systems

Elevated Control Rooms: Install the switchgear and SCADA/EMS systems in a flood-safe control rooms or on an elevated platforms with a minimum of 300 – 600mm above ground level or above local flood benchmarks whichever is higher.
Remote Isolation Systems: Provide remote shut off and sectional isolation options in the control room and near switchgear in case of water ingress.
Site Grading Measures: Provide / Implement site grading and trenching to channel surface runoff away from charging bays and electrical equipment.
Cable Trench Depth: Cable trenches are recommended to be installed with a depth of approximately 450 mm to accommodate 415V systems.
High-Voltage Cable Routing: Route high voltage cables away from potential water ingress paths, avoiding undercarriage-exposed zones and low-lying conduits.
Flood-Safe Charger Siting: Do not install Charging Stations in low-lying outdoor areas or locations prone to water accumulation or flooding. Mount Charging equipment at a safe height (400 – 600 mm above historic flood levels) to prevent damage from rain/water seepage or flooding.
Elevated Electrical Equipment: Position the crucial electrical components like transformers, RMUs, and LT panels at elevated levels (400 – 600mm above historic flood levels) to prevent damage.
Weather Shielding Measures: Shield the chargers to ensure longevity by limiting exposure to rain, which can cause degradation.
Humidity Control Systems: Install appropriate equipment and system in regions with frequent wet weather to monitor and control air humidity levels.

Design Standards

House chargers and distribution boxes in a minimum IP66 rated enclosures depending upon local context as per AIS-138, to ensure protection against dust and water ingress.
Equip the chargers with automatic disconnection mechanisms in case of ground fault, insulation failure, or water detection, as per AIS-138 Part 2, Clause 7.0.
Seal battery packs, connectors, wiring harnesses, and motor enclosures using industry-standard waterproof gaskets and hydrophobic coatings.
Position socket outlets and connector storage between 400 mm and 1500 mm above ground level, in accordance with AIS-138 Part 1.
Install flood alarms and moisture detection sensors at substations.
Enable chargers with remote diagnostics and control to manage risk during event of flood, water logging, extreme temperatures etc.
Install thermal, humidity, and water ingress sensors inside charger cabinets for early warning.

Standard Recommendation

Chargers with automatic disconnection mechanism: AIS-138 Part 2, Clause 7.0.
Socket outlets and connector storage: AIS-138 Part 1

CYBER SECURITY

Planning Recommendations

Effective implementation of cyber security requires targeted mitigation actions by relevant stakeholder, as outlined in the following table to support enforcement and ensure compliance.

S.No.

Activities

Responsibility

Cybersecurity Protection Measures

Secure Human Machine Interface (HMI) Interfaces:

Physical Port Security

Network Segmentation Strategy

IP Address Validation

Cybersecurity Protection Measures: Implement appropriate cybersecurity measures such as installation of firewalls, application of authentication measures, encryption of data, and installation of anti-virus programs to protect the product, the network, its system and the interface from security breaches, unauthorized access, leakage and data theft.
Secure Human Machine Interface (HMI) Interfaces: Secure HMI interfaces (touchscreens, card readers) with multi-factor authentication.
Physical Port Security: Lock USB and Ethernet ports; use tamper-proof enclosures.
Network Segmentation Strategy: Isolate Electric Vehicle Charging Station (EVCS) networks from public internet and internal depot systems.

Design Standards

Use Open Charge Point Protocol (OCPP) 2.0.1 or higher with Transport Layer Security (TLS) encryption and mutual authentication.
SQL Injection – Use parametrized queries to distinguish code from data.

STRUCTURAL SAFETY

Planning Recommendations

Successful implementation of structural safety requires targeted mitigation actions by relevant stakeholder, as outlined in the following table to support enforcement and ensure compliance.

S.No.

Activities

Responsibility

Safe Charger Siting

Corrosion Protection Measures

Minimum Safety Clearance

Secure Charger Enclosures

Surveillance Monitoring Systems

Traffic Zone Demarcation

Vehicle Alignment Aids

Physical Impact Barriers

Safe Charger Siting: Locate charging stations away from potential fire or explosion hazards, and placed them in areas with free form dust, corrosive gases, or on the downwind side of prevailing winds.
Corrosion Protection Measures: To prevent corrosion, use EVSE equipment with a waterproof rating of IP65/IP66 or higher, and install water detection sensors to enable automatic power shut off.
Minimum Safety Clearance: Maintain proper distance, minimum 1-2 meters between the charging units and parked buses.
Secure Charger Enclosures: House the charging stations in a fenced, secure and tamper resistant housing to prevent damage from protests and vandalism.
Surveillance Monitoring Systems: Install motion detectors and CCTV near the charging infrastructure.
Traffic Zone Demarcation: Define and clearly mark traffic zones around the chargers to prevent operational accidents and human negligence, and to avoid vehicular collisions.
Vehicle Alignment Aids: Install floor-level stopping guides to help drivers align accurately to prevent collision between e-buses and charging infrastructure.
Physical Impact Barriers: Install physical barriers or bollards near charging stations to safeguard equipment from accidental or deliberate vehicular impacts.

COMMON SAFETY MEASURES

Planning Recommendations

Effective implementation of common safety measures requires targeted mitigation actions by relevant stakeholder, as outlined in the following table to support enforcement and ensure compliance.

S.No.

Activities

Responsibility

Grid Resilience

Resilient Upstream Infrastructure

Charger Placement and Ratio

Safety from Technological Obsolescence

Emergency Action Plan

Surveillance Requirement

Grid Resilience

Adequate Connected Load: Obtain electricity connection (connected load) in the bus depot/ terminal, from the electric utility, in adequate capacity for the projected e-bus deployment during next 10 – 30 years.
Dual Power Feeds: Maintain dual/distributed power feeds from DISCOMs to manage incidents of power failures.
On-site Solar Integration: Installation of rooftop or elevated solar panels on administration building, parking structure or on top of charging infrastructure shed. Designs should be guided by shadow analysis, structural load capacity, and estimated solar potential (e.g., kWh/m²/year).
Renewable Backup Systems: Integrate with renewable sources (solar + hybrid inverters) for backup during emergency situations.
Battery Energy Storage: Pair the charging infrastructure with a Battery Energy Storage System (BESS) to provide emergency power backup and manage peak load demands during blackouts or grid failures. Integration with the Energy Management System (EMS) is critical.
Smart Grid Readiness: Depots should be designed to support future integration with smart power grids. While Vehicle-to-Grid (V2G) is still in the pilot stage in India, provision of bi-directional chargers and compatible electrical systems can be considered in forward-looking depots, subject to state DISCOM regulations.
Flood-Resilient Equipment: Elevate distribution transformers, ring main units (RMUs), and LT panels above historical flood levels.
Upstream Breaker Control: Ensure the upstream breaker Moulded Case Circuit Breaker (MCCB) or Earth-Leakage Circuit Breaker (ELCB) for the AC power supply is OFF, when EVSE are not in operations.
Utility Compliance Rules: Local regulations from distribution network operators will specify management protocols, testing frequency, and whether 24-hour access is required by the distribution network operators.
Transformer Redundancy: If a depot/ terminal requires a transformer of more than 1MW, operators are advised to consider multiple transformers of up to 2MW, to enhance reliability and to ensure continued operations in case one unit fails.

Resilient Upstream Infrastructure

Load Estimation: Load estimation to consider e-bus type, fleet size, and charger configuration. A 100-bus depot typically requires 4.5–6.0 MVA, with an additional 25–30% load margin planned for future expansion and resilience.
DISCOM Connection & Process:
- Obtain HT/EHT connection (typically 11 kV or 33 kV) based on load.
- Submit and align with DISCOM’s Supply Code Regulations.
Survey & Land Requirements:
- Adequate space for Electrical Substation (ESS) varies with load and voltage level.
- Space for transformers, switchgear, metering, and safety clearance zones.
Demand Estimate & Infrastructure Execution:
- DISCOM prepares demand note and outlines upstream network augmentation needs.
- Ensure test reports, safety certificates, and equipment clearances are available.
- Option to execute works via DISCOM or STU, with supervision charges.
Elevation & Flood Protection:
- Site ESS and transformers on raised plinths (minimum 0.6–1.0 m above 100-year flood level).
- Provide stormwater drainage, sump pumps, and waterproof cable trenches.
- Ensure graded slope and permeable pavement for effective runoff.
Safety and Protection Systems:
- Lightning protection, earthing, and surge arrestors for all equipment.
- Use IP67+ rated enclosures for outdoor electrical gear.
- Integrate real-time monitoring (SCADA/BMS) for overloads, short-circuits, and moisture ingress.

Charger Placement and Ratio

Bus – Charger Ratio: A commonly followed practice is a 4:1 bus-to-charger ratio, where one charger is shared by four buses to balance infrastructure costs and charging demand.
Smart Power Management: When multiple buses are charged simultaneously, smart power management is required to prevent overloading the grid. For example, depots may use overnight slow charging for full battery replenishment, complemented by daytime opportunity charging using short, high-power top-ups.

Safety from Technological Obsolescence

CCS2 Protocol Adoption: Adopt and enforce the CCS2 protocol across all charging infrastructure to ensure universal compatibility and interoperability, allowing e-buses to charge seamlessly and maintaining system resilience if any component fails.
OCPP-Compliant Chargers: Enforce the use of Open Charge Point Protocol (OCPP) compliant chargers and Charging Management System (CMS) for better interoperability.
Service Upgrade Agreements: Ensure regular upgrade and service agreement with the charging provider.
Software Firmware Updates: Regular software and firmware upgrades need to be there.
OCPI Interoperability Support: Ensure Open Charge Point Interface (OCPI) to facilitates network-to-network interoperability.
Smart Grid Integration: Implement smart grid integration with energy storage for dynamic power management.

Emergency Action Plan

Emergency Response Plan: Prepare an emergency plan that instructs operators what to do in case of an emergency.
Pre-Operation Approval: Obtain approval of a trained technician or third-party engineer before operating the EVSE.

Surveillance Requirement

Safety Monitoring Systems: Install safety monitoring systems including video surveillance, intrusion alarm and access control at entry and exit points of large charging stations
Expanded Camera Coverage: Increase coverage by cameras to the charging area and business counters and integrate them with the fire alarm system. Position the cameras and other equipment securely to avoid damage.
Continuous Data Recording: Support all surveillance system with 24-hour recording capacity, with minimum data retention period of 30 days and capability for low-light or nighttime imaging.