In railway engineering, nothing happens by accident. Every wiring harness, every controller, every bracket must meet specific requirements defined not by preference, but by standards that ensure safety and predictable performance.
Electronic equipment: EN 50155
Although this article focuses on EN standards related to electronic equipment, cabling and fire behaviour, it’s worth noting that the EN family also includes system-level lifecycle standards such as EN 50126 for RAMS.
One of the key pillars for onboard electronics is EN 50155:2022-05 Railway applications – Rolling stock – Electronic equipment. It defines how electronic devices in rolling stock must behave under real operating conditions, covering:
- temperature ranges and thermal cycling
- humidity, condensation and pollution
- shock and vibration
- voltage fluctuations, supply interruptions and transient phenomena
- EMC performance
For control units, communication modules, diagnostic devices or ETCS components, EN 50155 sets the baseline for durability and robustness in service conditions.
Cabling, installation and fire safety: EN 50343, EN 50264-1, EN 45545-2
Safe electrical integration depends not only on electronics, but on how wiring systems are designed, installed and protected.
The installation process is governed by EN 50343:2025-07 Railway applications – Rolling stock – Rules for installation of cabling.
It sets requirements for:
- routing and protection of cable runs
- minimum bending radii
- fastening, clamping and strain relief
- separation from heat sources and moving parts
- inspection and post-installation testing
This is the key standard that ensures a wiring design is correctly implemented on the physical vehicle.
Cable materials themselves fall under EN 50264-1:2008 Railway cables with special fire performance – Part 1: General requirements, which specifies insulation, mechanical performance and fire resistance for cables used in rolling stock.
For all materials used inside the vehicle including cables, connectors, conduits, insulation and structural plastics – EN 45545-2+A1:2024-04 Railway applications – Fire protection on railway vehicles – Part 2: Requirements for fire behaviour of materials and components defines classification, fire behaviour, smoke and toxicity requirements.
Together, EN 50343, EN 50264-1 and EN 45545-2 create a complete framework for safe, compliant and durable wiring systems.
ISO standards: a wider view of railway engineering
ISO 19659-3:2022 Railway applications – Heating, ventilation and air conditioning systems for rolling stock – Part 3: Energy efficiency establishes criteria for HVAC energy performance — especially relevant as operators seek lower energy consumption.
ISO 10326-2:2022 Mechanical vibration – Laboratory method for evaluating vehicle seat vibration – Part 2: Application to railway vehicles defines methods for assessing seat vibration exposure, contributing to long-term passenger and driver comfort.
ISO 21106:2019 Railway applications – Recyclability and recoverability calculation method for rolling stock provides a methodology for assessing recyclability and material recovery of vehicles.
ISO 9466:2025 Railway applications – Coating of passenger rail vehicles specifies requirements for coating systems that ensure long-term corrosion protection and durability.
ISO 9828-1:2025 Railway applications – Fire protection on railway vehicles – Part 1: General defines general principles for fire protection, offering a system-level perspective that complements EN 45545.
ISO standards don’t replace EN standards – they enrich them by looking beyond individual components and addressing how the entire vehicle performs throughout its life.
Standards are just the beginning
Working with standards is never simple – behind every requirement stands not just theory, but a set of precise rules that can vary from one manufacturer to another. Many OEMs maintain their own internal standards, often even more detailed or demanding than the international ones.
Before any documentation is created, an experienced engineer begins with an analysis of the applicable requirements and standards. This step determines the entire project: from system architecture to wiring harness design and validation strategy.
Each project stage ends with a review of design data and documentation to ensure compliance with the relevant standards. This takes form in analyses such as FMEA, hazard and risk assessments (based on EN 50126 principles), and D-FMEA, followed by P-FMEA during production. All these activities serve one purpose: to manage risk and ensure functional and human safety.
This isn’t done for the sake of the process – the process and the OEM require it, and the results accompany the product throughout its entire lifetime.
More than formality
From the outside, standards can look like bureaucracy. In reality, they let engineers from different disciplines and industries speak the same language. When we design electrical systems, wiring harnesses or embedded software, standards become the common reference point ensuring that what works on paper also works in the real world.
Good processes, shared principles and respect for the rules are what make engineering not only creative, but responsible.