ISO 7240-17:2020

Overview

ISO 7240-17:2020 is an international standard developed by ISO that addresses transmission path isolators used within fire detection and fire alarm systems for buildings. This standard is a critical part of the broader ISO 7240 series dedicated to ensuring the robustness and reliability of fire alarm systems. Specifically, ISO 7240-17:2020 details the requirements, test methods, and performance criteria that transmission path isolators must meet to perform effectively in real-world environments.

Transmission path isolators play a key role in limiting the negative impact of faults, such as short circuits, in the wiring of fire alarm systems. By isolating issues and maintaining loop integrity, these devices help keep the overall alarm system operational even if a section of the transmission path becomes compromised.

Key Topics

• Scope and Purpose: Covers requirements for isolators used in transmission paths of fire alarm system loops, excluding those integrated into control and indicating equipment.
• Product Definitions: Clarifies critical terms such as transmission path isolator, closed condition, open condition, field device, and non-field device.
• Design and Adjustment:
  • Isolators must operate as specified in the manufacturer’s documentation.
  • Protection against unauthorized adjustments and requirements for both manufacturer and on-site settings.
  • Software-controlled isolators must ensure data integrity with non-volatile memory and secure programming.
• Status Indication: If provided, status indicators must avoid red, which is typically reserved for fire alarm signals.
• Test Requirements: Rigorous test methods covering:
  • Functionality under normal and fault conditions
  • Environmental resilience (heat, cold, humidity, corrosion, vibration, shock)
  • Electromagnetic compatibility (EMC) and immunity
• Installation Guidance: Manufacturers are required to provide comprehensive technical data for system designers to ensure correct selection and integration.
• Compliance and Reporting: Transmission path isolators must be tested for reproducibility and report performance data in line with the prescribed test schedule.

Applications

Transmission path isolators, as standardized by ISO 7240-17:2020, are essential for:

• Commercial and Public Buildings: Ensuring continued protection in offices, hospitals, schools, and other occupancies where fire alarm system reliability is paramount.
• Complex Fire Alarm Loops: Protecting multi-device circuits by segmenting the wiring into manageable sections, so faults in one segment don't disable the entire system.
• Retrofitting and Upgrading: Providing compatibility and enhanced resilience in both new installations and upgrades of older fire detection systems.
• Meeting Regulatory Requirements: Helping building owners, system designers, and installers comply with international safety regulations and facilitate approvals from authorities.

Related Standards

ISO 7240-17:2020 works alongside several other key standards in the fire detection and alarm field, including:

• ISO 7240-1: Fire detection and alarm systems - General requirements and definitions
• IEC 60068 series: Environmental testing for electronic components, including considerations for heat, cold, vibration, shock, and corrosion
• IEC 62599-2: Alarm systems - Electromagnetic compatibility and immunity requirements
• Other parts of ISO 7240 series: Covering components like smoke detectors, heat detectors, and control equipment

By adhering to ISO 7240-17:2020, manufacturers, specifiers, and installers ensure that transmission path isolators enhance the resilience and reliability of fire alarm systems, minimizing risks associated with wiring faults and supporting the safety of building occupants.