What's New in CAN/ULC-S524: Key Changes Every Fire Alarm Installer Should Know
Fire alarm systems protect lives — but only when they're installed correctly and to the latest standard. The 2019 edition of CAN/ULC-S524, the Standard for the Installation of Fire Alarm Systems, brings some of the most significant updates in years. Whether you're an electrician, fire alarm technician, or engineer, here's what you need to know.
Why These Updates Matter
Fire alarm installation is a three-stage process: a system is designed by an engineer in accordance with applicable building code and standards requirements, installed by a qualified installer following the design, the Canadian Electrical Code, ULC Standards and manufacturer's instructions, and verified by a fire alarm technician, electrician, or engineer. Each of these roles depends on a current, clearly written standard — and the 2019 edition of S524 delivers exactly that.
Importantly, the 2019 editions of S524 and S537 are now referenced by the National Building Code 2020, while the 2019 edition of CAN/ULC-S536 is referenced by the National Fire Code 2020 and the Ontario Fire Code 2025. This alignment means the three core fire alarm standards were developed together for consistency — a major win for anyone working across installation, inspection, and verification.
A More Organized Standard
One of the most practical structural improvements is the introduction of a continuous section numbering system, running from Section 1 through to Section 52. In previous editions, navigating between sections could be inconsistent. The new structure also incorporates tables and figures directly within the standard's text, making technical requirements much easier to reference on the job.
The glossary has also been expanded with key new definitions, including:
• Main Power Supply – the primary source of electrical energy for the fire alarm system
• Risk Analysis – a documented process assessing likelihood, vulnerability, and magnitude of emergency scenarios
• Site-Specific Data – alterable control unit data for a defined system configuration (e.g., labelling and zoning)
• Suite Fault Isolator – ensures a short circuit in one residential suite doesn't disable signal devices in another
• Zone – a building area with a separate visible indication at the control unit
Circuit Fault Tolerance: A Critical New Requirement
Section 18 introduces new circuit fault tolerance requirements that directly affect how installers wire and protect systems. The core rule: where any fire alarm circuit serves more than one National Building Code-required fire alarm zone, a single fault — whether open circuit, short circuit, or ground fault — shall not prevent normal operation in more than one zone.
There are specific time allowances when a short circuit occurs during an active alarm condition in accordance with Table 4.3.
Fault isolators, including addressable (uniquely identified) isolators, are an accepted method for meeting these requirements. Section 48 has also been revised to bring audio isolators, power bus isolators, and equipment bus isolators all under the fault tolerance framework.
New: Suite Fault Isolators
Section 49 introduces a way, if used to meet the requirements of the National Building Code, to protect the audible signal devices in residential suites from an open circuit and not impair signal devices within other suites, using suite fault isolators in residential and care occupancy buildings. Using suite fault isolators can be a way to ensure that an open or short circuit on a signal circuit within one suite cannot knock out alarm notification in neighbouring suites — a particularly important life-safety measure in multi-unit residential buildings.
Wireless Devices and Modern Wiring
The 2019 edition formally addresses the use of wireless (short-range radio frequency) devices, recognizing the growing prevalence of these systems in modern installations.
For data communication, a new Data Communication Link Style N (DCLN) pathway has been added, including Ethernet wiring. Key installation rules for DCLN include:
• Wiring must follow CSA C22.1 (Canadian Electrical Code), Section 32 — Fire Alarm Wiring
• DCLN shall be dedicated to the fire alarm system only
• Mechanical protection equivalent to conduit installations is required
• Fibre optic cables used for DCLN must comply with Section 8 (Optical Fibre Cables)
• Each junction access enclosure must be marked in accordance with Section 8.5
Power Supply Updates: UPS and Generators
Section 5 introduces significant new rules around Uninterruptible Power Supplies (UPS) for fire alarm systems. Highlights include:
• UPS input and output connections must be hard-wired and permanent, in accordance with CEC Section 32
• A means to disconnect the UPS while maintaining power continuity to the fire alarm system must be provided, with a locking device to prevent unauthorized operation
• Where a UPS serves a central building system, it must be backed by emergency generators with sufficient fuel for the full fire alarm load cycle per CSA C282
• An off-normal UPS position must trigger a non-latching supervisory or trouble signal on the fire alarm system
Additionally, where an engine-driven generator is provided, a "generator running" condition must produce a non-latching supervisory signal on the fire alarm system.
Expanded Device Coverage
The 2019 edition adds or revises requirements across a wide range of device types:
• Carbon Monoxide (CO) detection – new sections cover CO detectors connected to the fire alarm system, and CO detectors used in lieu of CO alarms (CAN/ULC-S524 Section 36 & 37)
• Gas and vapour detection – location and spacing must follow manufacturer's instructions; devices must initiate a gas alarm signal per CAN/ULC-S588 (CAN/ULC-S524 Section 38)
• Smoke detectors in lieu of smoke alarms – permitted in suites of residential occupancy under CAN/ULC-S524 Section 30
• Strobe lights (visible signal devices) – updated requirements under CAN/ULC-S524 Section 42
• Air sampling systems – addressed in CAN/ULC-S524 Section 33
• Galleries, mezzanines, interior balconies, exit stair shafts, and elevator hoistways – each receive updated detector placement requirements under CAN/ULC-S524 Section 28
Fire Suppression Releasing Systems
An entirely new Section 52 covers fire suppression releasing systems. Key notification rules include:
• Devices warning occupants to evacuate a protected space and devices warning people not to enter must each provide unique notification — they cannot use the same signal
• Audible devices for local suppression notification must produce a sound different from the building fire alarm signal
• Visible signal devices for suppression notification must either produce a distinct visual signal or be clearly labelled to distinguish them from standard fire alarm strobes
Large-Scale Network Systems
Section 20 adds new requirements for large-scale network fire alarm systems — defined as systems with more than 1,000 total active field devices or systems located in buildings within the scope of NBC Subsection 3.2.6. Each control unit or transponder in such a system must house all components required to provide complete functionality for both inputs and outputs for the area it serves.
Reference Standards You Need on Your Radar
S524-2019 references several companion standards for situations not directly covered in the main text:
Table 1: Referenced ULC Standards
Conclusion
The 2019 edition of CAN/ULC-S524 is a well-structured, modernized standard that reflects how fire alarm systems are actually being designed and installed today. Staying current with these changes isn't just good practice — it's your professional obligation and a critical part of keeping buildings and their occupants safe.
Whether you're installing fault isolators in a high-rise residential building, wiring DCLN pathways for a campus network system, or integrating carbon monoxide detection with a fire alarm system, understanding these updates ensures compliance, improves safety, and demonstrates your commitment to excellence in the fire safety industry.
Certi-Fire is leading the way for the understanding of the fire alarm requirements. Contact Certi-Fire for more information.