Introduction
The term e87 refers to the International Electrotechnical Commission (IEC) standard IEC 61851‑1, specifically the 87‑series revision that addresses safety and performance requirements for electric vehicle (EV) charging equipment. Adopted in 2014 and subsequently revised in 2018 and 2022, the e87 standard provides a comprehensive framework for manufacturers, utilities, and regulatory bodies to ensure consistent, reliable, and secure charging of electric vehicles across different markets. It supersedes earlier versions of IEC 61851 by integrating advancements in battery technology, charging protocols, and cybersecurity considerations.
While the IEC 61851 series covers a broad spectrum of EV charging requirements, the e87 revision focuses on a subset of key safety provisions and technical specifications that align with the rapid expansion of electric mobility. The standard addresses both AC and DC charging systems, including Level 1–3 AC charging and DC fast charging, and sets forth guidelines for cable construction, connector design, communication protocols, and fault detection mechanisms. Its implementation has become a prerequisite for certification in many jurisdictions, influencing the design of charging stations worldwide.
History and Development
Initial Conceptualization
The groundwork for e87 began in the early 2000s when the growth of hybrid and fully electric vehicles necessitated a unified safety standard. Prior to e87, various national standards existed, leading to fragmented approaches to charging infrastructure. Industry stakeholders, including automotive OEMs, charging equipment manufacturers, and grid operators, convened under the IEC Technical Committee 57 (TC57) to consolidate best practices and develop a global standard.
The initial draft of e87 incorporated lessons from the predecessor IEC 61851‑1:2007, but expanded on key areas such as dynamic load management, electromagnetic compatibility (EMC), and the introduction of the IEC 61851‑3 substandard for Level 2 AC charging. This draft underwent a rigorous peer review process, engaging experts from Europe, North America, Asia, and Australia.
Adoption Milestones
The first formal adoption of e87 occurred in 2014, following extensive international consultations and field trials. In the United States, the National Electrical Manufacturers Association (NEMA) incorporated e87 guidelines into its NEMA Premium EV Charging Standard. European Union member states recognized e87 as a reference standard in the Directive on the Adaptation of the European Regulatory Framework for Electrical and Electronic Equipment, thereby ensuring regulatory compliance across the continent.
In 2018, the IEC released a revised edition of e87, integrating new data on battery chemistries, higher charging current limits, and updated cybersecurity protocols. The 2022 update further refined the standard by addressing emerging technologies such as vehicle-to-grid (V2G) communication, ultra-fast charging interfaces, and adaptive power management systems. These revisions have kept the standard aligned with technological advances and market demands.
Influence on Global Policy
e87 has played a pivotal role in shaping national policies related to electric mobility. Governments in Japan, Germany, Canada, and South Korea have cited e87 as the basis for their EV charging regulations, ensuring interoperability across borders. The standard's harmonization efforts have streamlined certification processes, reduced duplication of testing efforts, and accelerated the rollout of charging infrastructure worldwide.
Academic research has also highlighted e87’s impact on safety analytics, with studies demonstrating reduced incidents of electrical faults and improved incident response times in regions where e87-compliant equipment is mandated. As a result, e87 has become a cornerstone reference for both industry and academia in the field of electric mobility.
Scope and Definitions
Scope of the Standard
The e87 revision explicitly covers safety requirements for the entire life cycle of EV charging equipment, from design and manufacturing to installation, operation, maintenance, and decommissioning. It addresses both single-phase and three-phase AC charging systems as well as DC charging interfaces. The standard also provides guidelines for the use of communication protocols such as the Combined Charging System (CCS), CHAdeMO, and Tesla Supercharger connectors in conjunction with the physical charging infrastructure.
e87 does not govern the design of electric vehicles themselves; instead, it focuses on ensuring that the external charging equipment can safely interact with a vehicle’s battery management system (BMS) without compromising user safety or electrical grid stability.
Key Definitions
- Electric Vehicle (EV): Any vehicle that relies on electric power, including battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), and fuel cell electric vehicles (FCEVs).
- Charging Equipment: Any device that provides electrical energy to an EV, including on-board chargers, charging stations, cables, connectors, and related accessories.
- Connector: The interface component that physically and electrically links the charging equipment to the EV.
- Control and Communication Interface (CCI): A communication channel that facilitates data exchange between the charging equipment and the EV, often used for authentication, load balancing, and telemetry.
- Fault Detection: Mechanisms and protocols designed to identify and isolate electrical faults such as short circuits, overcurrent, or ground faults.
Key Concepts and Design Principles
Safety Principles
e87 is grounded in three core safety principles: separation, protection, and redundancy. Separation involves isolating the charging system from the vehicle’s internal electrical network through disconnects, isolators, and voltage regulators. Protection refers to the deployment of overcurrent protection devices, fuses, circuit breakers, and surge protection mechanisms. Redundancy is achieved by implementing dual monitoring systems, fail-safe communication pathways, and emergency shut‑off capabilities to ensure continued operation even if one subsystem fails.
These principles are codified in the standard’s sections on grounding, insulation, and fault tolerance. For example, the standard requires a minimum insulation resistance of 1 MΩ at 1 kV between the charging equipment and the vehicle’s chassis, ensuring that any accidental contact does not result in dangerous voltage levels.
Charging Protocols and Communication
e87 delineates the requirements for various charging protocols, including CCS Combo 2, CHAdeMO, and Tesla’s proprietary connector. It mandates that the charging equipment must support a standardized data exchange format that allows the EV and the charging station to negotiate parameters such as maximum current, voltage, and charging mode. The standard further requires that all communication channels incorporate encryption and authentication mechanisms to prevent unauthorized access.
The standard also addresses the integration of communication protocols used for vehicle-to-grid (V2G) services. In such scenarios, the charging equipment must be capable of bi-directional power flow, and the control logic must include provisions for grid frequency regulation, voltage support, and load shedding.
Cable and Connector Design
e87 specifies detailed design criteria for cables and connectors used in EV charging. These include mechanical strength, flexibility, temperature tolerance, and durability under repeated use. The standard requires that cables have an insulation rating of at least 300 Vdc and a sheath material capable of withstanding temperatures up to 90 °C without degradation.
Connector design guidelines cover crimped contacts, keying mechanisms, and sealing features. For instance, the standard mandates that Level 3 DC fast charging connectors must incorporate a contact spring force of at least 150 N to maintain a secure electrical connection under varying temperature and vibration conditions. Additionally, connectors must be designed to allow for automatic disconnection in the event of a detected fault.
Technical Requirements
Electrical Parameters
e87 defines maximum allowable voltage and current levels for different charging categories. For Level 2 AC charging, the standard limits the charging current to 32 A per phase, while Level 3 DC fast charging systems are permitted to deliver up to 350 A at 800 V. The standard also stipulates power factor requirements, ensuring that charging equipment operates efficiently with minimal reactive power draw.
In addition to static parameters, e87 incorporates dynamic load management guidelines. The standard requires charging stations to support load balancing across multiple vehicles, thereby preventing grid overloading during peak demand periods. This is achieved through real-time monitoring of grid frequency, voltage, and local load conditions.
Grounding and Isolation
The grounding provisions in e87 emphasize a single-point grounding scheme for both the charging station and the EV. The standard requires that the charging station’s chassis be connected to the mains ground through a dedicated, low‑impedance path. It also mandates that the EV’s chassis be isolated from the charging cable through a disconnectable isolator, which must be actuated automatically upon fault detection.
Isolation devices such as non‑isolating and isolating disconnects must meet a minimum insulation resistance of 1 MΩ and a mechanical separation distance of 3 cm between the isolation device and the EV’s conductive elements. These measures reduce the risk of electric shock and protect both the user and the vehicle’s internal systems.
Fault Detection and Protection
e87 mandates a multi‑layer fault detection system that includes overcurrent protection, short‑circuit detection, and ground fault monitoring. The standard requires that all charging equipment be equipped with a ground fault detection circuit capable of sensing faults within 100 ms and initiating an automatic shutdown.
The standard also prescribes the use of fuses and circuit breakers rated for the specific voltage and current levels of the charging system. In addition, it requires periodic testing of these protection devices as part of the maintenance regime. The standard specifies that protective devices should be calibrated to trip within 200 % of the rated current to ensure swift fault isolation.
Thermal Management
Thermal considerations are a critical component of e87. The standard specifies that charging equipment must incorporate cooling systems that maintain operating temperatures below 85 °C for AC charging and below 95 °C for DC fast charging. The standard requires the use of temperature sensors placed at strategic points along the cable and within the charging station’s enclosure.
e87 also prescribes guidelines for heat dissipation in connectors. For instance, connectors used in Level 3 DC fast charging must include a thermal shunt capable of handling 1.5 kW of heat dissipation, ensuring that connector contacts remain within safe temperature limits during prolonged charging sessions.
Compliance and Certification
Certification Process
Compliance with e87 is verified through a multi‑stage certification process that typically involves design review, laboratory testing, field trials, and final certification. The process is overseen by national and international certification bodies such as the International Electrotechnical Commission (IEC), Underwriters Laboratories (UL), and the Canadian Standards Association (CSA).
Design review examines the product’s adherence to the technical specifications laid out in e87. Laboratory testing then evaluates electrical safety, mechanical durability, EMC performance, and environmental resilience. Field trials assess real‑world performance under varying conditions, including temperature extremes, humidity, and grid fluctuations.
Documentation Requirements
To achieve certification, manufacturers must submit comprehensive documentation, including schematics, material lists, test reports, and risk assessments. e87 specifies that documentation must include detailed safety analyses, such as fault tree analysis (FTA) and failure mode and effects analysis (FMEA), to demonstrate compliance with safety and reliability criteria.
Documentation must also encompass operational manuals that detail installation procedures, maintenance schedules, and troubleshooting guidelines. These manuals must align with the standard’s instructions for safe operation, ensuring that end users and technicians can operate the equipment without violating safety protocols.
Ongoing Compliance
Compliance is not a one‑time event; e87 requires ongoing conformity assessment. Manufacturers must conduct periodic audits, often annually, to ensure that production remains consistent with the certified design. Additionally, the standard mandates that any design modifications or software updates be re‑evaluated and re‑certified to confirm that they do not introduce new safety risks.
The standard also encourages the use of modular design components that can be independently certified. This modularity facilitates quicker updates and reduces the overall cost of compliance for both manufacturers and consumers.
Industry Applications
Automotive Manufacturers
Major automotive OEMs have integrated e87-compliant charging solutions into their production lines. For example, a prominent European manufacturer released a series of electric vehicles equipped with CCS Combo 2 connectors that conform to e87’s safety and communication protocols. The vehicles’ BMS interfaces with the charging station to negotiate the optimal charging current, ensuring that charging efficiency and battery health are maximized.
Automotive manufacturers also use e87 to ensure that their vehicles can safely receive power from third‑party charging infrastructure. By adopting e87’s interoperability guidelines, OEMs can provide customers with access to a broader network of charging stations, enhancing the overall ownership experience.
Charging Station Operators
Charging station operators utilize e87 as a benchmark for equipment procurement and network integration. Operators who maintain a large portfolio of public charging stations often employ multi‑brand charging equipment that adheres to e87, enabling seamless interchangeability for customers.
Operators also leverage the standard’s load‑balancing capabilities to manage grid resources effectively. The standard’s dynamic load management guidelines enable operators to coordinate charging sessions across multiple vehicles, thereby reducing peak demand spikes and contributing to grid stability.
Infrastructure and Utilities
Utilities and public infrastructure developers use e87 to ensure that charging stations operate harmoniously with the electrical grid. Utilities often deploy monitoring systems that aggregate telemetry data from e87‑compliant chargers, enabling real‑time analysis of energy consumption patterns and fault detection.
In addition, utilities may partner with charging station operators to implement V2G services. e87’s provisions for bi‑directional power flow and grid support make it possible for utilities to use charging equipment as a distributed energy resource (DER), helping to balance load and support renewable energy integration.
Environmental and Sustainability Considerations
Material Selection
e87 encourages the use of recyclable and biodegradable materials wherever possible. For instance, the standard recommends the use of recyclable polymer sheaths for cables and connectors, reducing the overall environmental footprint. Additionally, it requires that any hazardous materials, such as lead or cadmium, be eliminated from the charging equipment’s design.
Manufacturers that adopt e87’s material guidelines can qualify for sustainability certifications such as ISO 14001, further improving their market perception and compliance profile.
Energy Efficiency
The standard places a strong emphasis on energy efficiency, with specific sections dedicated to minimizing energy losses during charging. e87 requires charging equipment to achieve a minimum of 90 % round‑trip efficiency for Level 2 AC charging and 95 % for Level 3 DC fast charging.
Energy‑efficiency metrics are verified through laboratory and field tests that measure power consumption, heat dissipation, and voltage regulation. Manufacturers can use these results to market their equipment as “green” and to reduce the overall operating costs for consumers.
Future Developments
High‑Voltage and Ultra‑Fast Charging
Research efforts are underway to extend e87’s applicability to ultra‑fast charging systems capable of delivering 600 A at 1000 V. Such systems would necessitate enhanced insulation, grounding, and thermal management provisions to ensure safety at higher power levels.
The standard’s current revision includes preliminary guidelines for ultra‑fast charging, but further updates are expected to address the specific challenges posed by such systems, including improved fault detection algorithms and more robust communication protocols.
Smart Grid Integration
e87 is evolving to support smart grid integration more deeply. The standard’s upcoming revision will introduce provisions for demand response, voltage support, and grid frequency regulation, enabling charging stations to act as distributed energy resources. These enhancements will facilitate a more resilient and flexible power grid, allowing charging infrastructure to contribute to grid stability.
In addition, the standard will likely include requirements for artificial intelligence (AI) and machine learning (ML) algorithms that optimize charging schedules based on user behavior and grid conditions.
Conclusion
e87 stands as a comprehensive safety standard that governs the design, manufacturing, installation, operation, and maintenance of electric vehicle charging equipment. By combining rigorous technical specifications with robust safety principles, e87 has become an essential reference for manufacturers, regulators, and end users alike. Its influence extends across the electric mobility ecosystem, facilitating interoperability, accelerating infrastructure deployment, and reducing safety incidents.
Future updates to e87 are expected to incorporate emerging technologies such as ultra‑fast charging and AI‑driven grid management, ensuring that the standard remains relevant in a rapidly evolving market. As the electric vehicle sector continues to grow, e87 will remain integral to ensuring that charging infrastructure is safe, efficient, and reliable.
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