CAN/ULC-S573

CAN/ULC-S573 is the Canadian standard for the installation of ancillary devices connected to fire alarm systems, meaning the equipment the panel drives that is not part of core detection and notification: magnetic door holders, damper and fan shutdown relays, elevator interfaces and similar outputs. The current published edition is CAN/ULC-573-2026, still the 1st edition, first published 28 December 2018 and last revised 10 July 2026. Neither the Ontario Building Code nor the Ontario Fire Code names S573 in its referenced documents table, so it does not reach your job directly. It arrives one level down, through CAN/ULC-S524 and CAN/ULC-S537, which reference it, and through the listing on the device itself.

What CAN/ULC-S573 covers

Installing the outputs. A fire alarm system does more than detect and annunciate: it releases door holders, shuts down air handling, drives damper controls, signals elevator controllers and operates other equipment that belongs to somebody else's system. S573 is the installation standard for those connections, and the devices it governs are what the trade calls ancillary devices.

Practically, it is the standard behind the wiring, supervision and interfacing arrangements between the panel and equipment the fire alarm contractor does not own. The relay that drops a magnetic door holder, the contact that shuts down a fan when a duct detector operates, the interface that sends an elevator to its recall floor: the fire alarm side of each of those is S573 territory even though the equipment on the far side is not.

What it does not cover

S573 does not cover the fire alarm system itself. Initiating devices, notification appliances and the circuits serving them are CAN/ULC-S524 work. It does not cover the equipment being controlled, which belongs to the mechanical, elevator or door hardware standards. And it does not prove that the interface performs. Demonstrating that the dampers actually close and the elevators actually recall is integrated systems testing under CAN/ULC-S1001, a different standard with a different trigger and a different report.

That pairing is the one to hold onto. S573 governs how you install the connection. S1001 governs how you prove the whole chain works.

Which code provision brings it into force in Ontario

None directly, and that is the honest answer. We read Division B Table 1.3.1.2 of the 2024 Building Code Compendium and Division B Table 1.2.1.A of the Ontario Fire Code, and S573 appears in neither. It is one of six standards in this family that no Ontario code designates.

That does not make it optional. It reaches a job the way the other undesignated product and installation standards do: S524 and S537 reference it, and S524 and S537 are designated. So the chain runs code, then S524, then S573. If somebody tells you the Ontario Building Code requires S573 compliance, they are describing that chain loosely.

We cannot tell you which edition of S573 applies on a given job, because the answer is inside S524:2019, which is copyrighted and paywalled. We have not read it and we are not going to guess.

Published edition versus what is designated

The current published edition is CAN/ULC-573-2026, sold with the "S" dropped. It is still the 1st edition, first published on 28 December 2018 and revised four times since, most recently on 10 July 2026. That is the pattern UL Canada now follows across the family: amendments are issued as new dated editions rather than as standalone amendment documents, so a standard can carry a 2026 designation while its edition number has not moved since 2018. Where each standard sits, published against designated, is tracked with dates in the edition tracker.

Where it shows up on site

On any job with door holders, air handling shutdown or elevator interfaces in the scope, which in Ontario means most buildings over a certain size. The two interfaces that generate the most rework are covered separately: elevator recall and duct smoke detectors.

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