Changes to CAN/ULC‑S537‑19: How Fire Alarm Verification Has Evolved
When a new or modified fire alarm system is turned over to an owner in Canada, CAN/ULC‑S537 is the standard that governs verification. The 2019 edition, CAN/ULC‑S537‑19, is now referenced by the 2020 National Building Code and is being pulled into provincial codes and enforcement across the country.
This article explains what has changed in S537‑19, what a “proper” verification now looks like, and what owners, engineers, and contractors should expect.
1. What CAN/ULC‑S537‑19 actually covers
CAN/ULC‑S537 is the verification standard: it is used once a fire alarm system is installed, before (and after) occupancy, to confirm that the system:
Is installed in accordance with CAN/ULC‑S524 (Installation of Fire Alarm Systems) and the design documents
Performs all of its intended functions as designed, including detection, signaling, control of ancillary systems, and monitoring connections
Is documented and recorded in a standardized way so future inspections under CAN/ULC‑S536 have a clear baseline
The 2019 edition was developed in parallel with S524‑19 and S536‑19, so that design, verification, and periodic inspection now follow a consistent structure.
2. New structure, glossary, and verification records
Expanded glossary and clearer terms
S537‑19 introduces an expanded glossary and more precise terms for concepts like “deficiency” and “recommendation.”
This matters because those terms now tie directly into how findings must be recorded and acted on.
A deficiency refers to a condition where equipment or installation does not meet the applicable standard, design, or intended function.
A recommendation is an improvement suggestion that does not prevent the system from meeting its required performance.
The distinction is important for owners, because deficiencies demand correction; recommendations inform upgrades and capital planning.
Fire Alarm System Verification Records (new section)
One of the most visible changes is the addition of a full section on Fire Alarm System Verification Records.
S537‑19 includes standardized tabular forms that must be used for verification inspections and tests.
The standard allows companies to recreate the forms (and add logos), but the tests, wording, order, and structure cannot be changed.
These forms cover system information, control units and transponders, field devices, power supplies, circuit fault tolerance, ancillary devices, interconnections to fire signal receiving centres, deficiencies, and recommendations.
For owners and AHJs, this means verification reports from different firms should now look broadly similar and be easier to read and compare.
3. Documentation expectations at verification
S537‑19 places significant emphasis on documentation being complete and available on site at the time of verification.
Key requirements include:
The verifier must confirm that critical documentation exists and is kept in a single, accessible location, including:
Fire alarm drawings showing zoning, device addresses, and locations of control units, transponders, annunciators, power supplies, and fault isolators
Wiring schematics (block diagrams and risers) showing interconnections between devices and equipment
A description of the sequence of operation, including any programmed logic or deviations from default behaviour
Installation instructions, device lists, and details of air‑sampling pipe network design where applicable
Information on connections to any fire signal receiving centre, including site‑specific software where used
Required documentation that is missing must be recorded as a deficiency in the verification report.
A copy of the verification report must be provided to the owner and remain accessible on site throughout the life of the system.
This tightens the link between design, installation, and verification: without proper documentation, verification is considered incomplete.
4. Wiring and circuit fault tolerance tests
The 2019 edition introduces more explicit and structured tests for circuits and fault tolerance.
Supervised circuits and individual field devices
S537‑19 requires that each field device be inspected and tested to confirm:
Correct field termination, conductor type and gauge per the Canadian Electrical Code and manufacturer instructions
Correct circuit polarity and proper supervision (open‑circuit or device removal must generate a trouble signal)
Correct annunciation and fault response as per the design and zoning documentation
These checks are recorded on device‑level forms, linking each device to its address, zone, and results.
Data Communication Links (DCLs) and non‑DCL circuits
To align with the performance‑based circuit fault tolerance approach in S524‑19, S537‑19 adds structured tests for both DCL and non‑DCL circuits:
DCL without fault isolation:
Introduce a wire‑to‑wire short on each data link in a non‑alarm condition.
Confirm that trouble is annunciated and that devices on adjacent links continue to operate and signal properly.
Record results in the Circuit Fault Tolerance Test Sheet.
DCL with fault isolators:
Short the wiring on the isolated side; confirm annunciation of the fault.
Then operate a device on the source side and confirm activation is seen at the control unit/transponder.
Non‑DCL circuits serving multiple zones:
Short the wiring on the isolated side during non‑alarm condition.
Confirm trouble annunciation, then operate devices on the source and return sides and confirm proper activation outside the faulted section, within the system response times defined in Table 6.1.
The aim is to ensure that a single fault cannot compromise multiple National Building Code fire alarm zones beyond defined limits.
5. Control units, transponders, and ancillary circuits
S537‑19 places more detail around how control units and transponders are inspected and tested during verification.
Control unit and transponder inspections
The standard requires the verifier to confirm:
Input and output circuit designations are correctly identified in relation to connected field devices
Common control functions and indicators are correctly labelled
Plug‑in modules and cables are secure and properly seated
Time and date settings correspond to local conditions
Each control unit or transponder has its own inspection form, which must be completed in full.
Functional tests
S537‑19 prescribes tests to confirm:
Common visual and audible trouble signals operate correctly
Alarm signal silence and resound behaviour (including subsequent alarm operation) is as designed
Main power failure, emergency power changeover, and battery disconnection all produce the required trouble indications
Input‑to‑output operations, including ancillary device circuits, function as per the documented input/output matrix and sequence of operation
Ancillary device circuits—such as elevator recall, HVAC shutdown, door release, or other building systems—must be documented and tested, at least to confirm that the fire alarm system issues the correct control signal.
6. Interconnection to fire signal receiving centres
Where a system is connected to a fire signal receiving centre (e.g., monitoring station), S537‑19 requires explicit testing of that interface:
Confirmation that the transmitter is either integral to the fire alarm control unit or correctly interconnected
Verification of receipt of alarm, supervisory, and trouble signals at the receiving centre
Testing that disabling or bypassing the transmitter produces a specific trouble signal locally and, where applicable, at the receiving centre
Recording the name and telephone number of the fire signal receiving centre
These tests are documented on a dedicated Interconnection to Fire Signal Receiving Centre form.
7. Power supplies, batteries, and generators at verification
S537‑19 coordinates closely with the power requirements of S524‑19 and the testing practices of S536‑19.
Power supply inspections
The verifier must confirm that each power supply (control unit, transponder, remote power supply):
Conforms to CAN/ULC‑S524 and the Canadian Electrical Code, including proper disconnect means and fusing
Has adequate capacity for the system load, including any ancillary devices where the fire alarm power supply is used
Is correctly documented, with ancillary loads clearly identified
Battery testing and capacity calculations
For batteries, S537‑19 requires:
Verification that installed batteries are of the correct type and capacity as recommended by the manufacturer
Performance of battery tests using acceptable methods (24‑hour supervisory plus alarm load, silent accelerated test, or manufacturer’s method), with test completion voltages recorded
Calculation of required battery capacity, using supervisory and alarm currents and applying manufacturer‑specified derating factors, with results documented in the verification report
Confirmation that battery voltage after testing meets defined minimum thresholds, otherwise batteries must be replaced
Emergency power generators
Where a generator is used to supply fire alarm power, S537‑19 expects the verifier to witness tests confirming:
The generator provides power to the AC circuit serving the fire alarm system
Generator trouble and run conditions result in appropriate common trouble and visual indicators at the annunciator
Testing is coordinated with generator testing and consistent with applicable CSA standards for emergency electrical power supplies
8. Field devices: manual stations, heat, smoke, CO, and wireless
S537‑19 also refines the verification of individual device types.
Manual stations: Must be accessible, tested according to their operating instructions (including both stages in two‑stage systems), and confirmed to produce alarm signals within the required response time in the same zone.
Heat detectors: Must be tested using safe methods (no open flames or gas‑fired sources), with restorable and non‑restorable detectors treated differently; non‑restorable devices can be tested by simulating electrical operation and via lot sampling.
Smoke detectors: Must be visually inspected for cleanliness, tested with smoke or simulated smoke, and confirmed to operate within their sensitivity range or the ULC-537 (Table 16.1) default obscuration limits when manufacturer data is unavailable and record the device sensitivity rating in the report under remarks.
Air‑sampling and duct detectors: Must be tested for correct installation, airflow and transport time (for air‑sampling), and functional response to smoke introduced at sampling ports or tubes.
CO detectors connected to the fire alarm system: Must be located and spaced per manufacturer instructions and NBC requirements, with orientation suitable to the hazard.
Wireless devices: Must be installed according to plan, specifications, manufacturer's instructions and the system must annunciate removal or loss of devices, often with device‑specific trouble indications; gateways and transceivers must be tested according to their circuit roles.
All tests and results are recorded in detailed Field Device Record forms.
9. What S537‑19 means for you
For building owners and managers
Expect more rigorous verification of new or modified systems and more detailed reports at turnover.
Ensure design documents, sequences of operation, drawings, and device lists are complete and available before scheduling verification.
Keep all verification records on site; they will form the history of the installation of the system and baseline for future inspections and AHJ reviews.
For engineers and designers
Reference CAN/ULC‑S537‑19 explicitly in specifications for fire alarm verification.
Provide clear input/output matrices and sequences of operation so verifiers can test against the intended design.
Design circuits and zoning with fault‑tolerance and verification testing in mind.
For fire alarm contractors and verifiers
Update verification procedures and forms to match S537‑19’s required structure.
Train staff on new tests for DCL/non‑DCL circuits, power supplies, wireless devices, and interconnections to monitoring centres.
Be prepared to clearly differentiate deficiencies from recommendations and support owners through the correction process.
10. Using verification as a strength, not just a checkbox
CAN/ULC‑S537‑19 aims to make verification more consistent, transparent, and tied to actual performance rather than minimal paperwork.
By aligning design, installation, verification, and periodic inspection, it reduces surprises later in the life of the system and makes it easier to demonstrate compliance when it matters.
If you are commissioning new fire alarm work, now is the time to ensure that your verification practices—and your documentation—match the 2019 edition.