ISO 6469-3 - Battery Design

Electrically Propelled Road Vehicles — Safety — Protection of Persons Against Electric Shock

ISO 6469-3 is an international standard that specifies requirements to protect occupants, first responders, and service personnel from electric shock hazards in battery electric vehicles (BEV), hybrid electric vehicles, plug-in hybrid electric vehicles (PHEV), and fuel cell vehicles. It defines isolation resistance requirements, creepage and clearance distances, protection against direct and indirect contact with high-voltage circuits, and the design of the high-voltage interlock loop (HVIL).

Published by: International Organization for Standardization (ISO)
Current edition: ISO 6469-3:2021
Part of series: ISO 6469-1 (RESS safety), ISO 6469-2 (operational safety)

Scope

ISO 6469-3 applies to road vehicles powered by traction batteries with a working voltage above 60 V DC or 30 V AC. Requirements cover protection in normal operation, following a single fault, and after a vehicle crash. It applies during vehicle use and to service operations performed by trained technicians.

Key Requirements

Isolation Resistance

The high-voltage system must maintain a minimum isolation resistance between the high-voltage bus and the vehicle chassis. For DC systems, a minimum of 100 Ω/V is required; for AC systems, 500 Ω/V. An isolation monitoring system (IMS) must detect when isolation falls below the threshold and warn the driver.

Protection Against Direct Contact

High-voltage components must be enclosed or guarded so live parts are not accessible without tools. Minimum IP (ingress protection) ratings are specified for high-voltage connectors and enclosures. Orange colour coding of high-voltage cables and components is required for identification.

High-Voltage Interlock Loop (HVIL)

An HVIL (high-voltage interlock loop) circuit monitors the integrity of high-voltage connector and cover closures. Any disconnection of an HV connector or removal of an access cover must trigger automatic isolation of the high-voltage bus within a defined response time, protecting service personnel working on the vehicle.

Disclaimer: This is not a definitive guide, just an indication and it is important that you always go back to the source for legislation.