ULC CAN/ULC 538:2020 (R2025) Standard for Single and Multiple Station Carbon Monoxide Alarms for Non-Residential Applications

PREFACE

This is the First Edition of CAN/ULC 538, Standard for Single and Multiple Station Carbon Monoxide Alarms for Non-Residential Applications.

This First Edition of the Standard was developed by the ULC Standards Working Group on Carbon Monoxide Alarms, and was formally approved by the ULC Committee on Fire Alarm and Life Safety Equipment and Systems.

This Standard has been developed in compliance with the requirements of SCC for accreditation of a Standards Development Organization.

Only metric SI units of measurement are used in this Standard. If a value for measurement is followed by a value in other units in parentheses, the second value may be approximate. The first stated value is the requirement.

Annex A, identified as Informative, is for information purposes only.

In Canada, there are two official languages, English and French. All safety warnings must be in French and English. Attention is drawn to the possibility that some Canadian authorities may require additional markings and/or installation instructions to be in both official languages.

Attention is drawn to the possibility that some of the elements of this Canadian standard may be the subject of patent rights. ULC Standards shall not be held responsible for identifying any or all such patent rights.

Requests for interpretation of this Standard should be sent to ULC Standards. The requests should be worded in such a manner as to permit a “yes” or “no” answer based on the literal text of the requirement concerned.

This CAN/ULC 538 Standard is under continuous maintenance, whereby each revision is approved in compliance with the requirements of SCC for accreditation of a Standards Development Organization. In the event that no revisions are issued for a period of four years from the date of publication, action to revise, reaffirm, or withdraw the standard shall be initiated.

Comments or proposals for revisions on any part of the Standard may be submitted at any time. Proposals should be submitted via a Proposal Request in the Collaborative Standards Development System (CSDS) at https://csds.ul.com.

This Standard is intended to be used for conformity assessment.

Scope

1.1 These requirements cover electrically operated single and multiple station carbon monoxide (CO) alarms intended for protection in non-residential or ordinary (nonhazardous) areas.

1.2 Carbon monoxide alarms covered by these requirements are intended to respond to the presence of carbon monoxide from sources such as, but not limited to, exhaust from internal-combustion engines, abnormal operation of fuel-fired appliances, and fireplaces. Carbon monoxide alarms are intended to alarm at carbon monoxide levels below those that cause a loss of ability to react to the dangers of carbon monoxide exposure. See Table 39.1, Part A, Alarm – carbon monoxide concentration and response time.

1.3 Carbon monoxide alarms covered by this standard are not intended to alarm when exposed to longterm, low-level carbon monoxide exposures or slightly higher short-term transient carbon monoxide exposures, possibly caused by air pollution and/or properly installed/maintained fuel-fired appliances and fireplaces. See Table 39.1, Part B – False alarm resistance specifications.

1.4 These requirements, where applicable, also cover all remote accessories that may be connected to or are intended to be employed with a single or multiple station carbon monoxide alarm. See 35.2.1.

1.5 Carbon monoxide alarms covered by this Standard shall be installed, tested and maintained in accordance with the National Building Code of Canada, the National Fire code of Canada and with the Authority Having Jurisdiction.

1.6 This standard does not cover the following:

a) Single and multiple station smoke alarms that are covered by the Standard for Smoke Alarms, CAN/ULC 531;

b) Smoke alarms of the non-self contained type that are intended for connection to a household or industrial system control unit. These are included in the Standard for Smoke Detectors for Fire

Alarm Systems, CAN/ULC 529;

c) Mechanically operated single and multiple station fire alarm devices that are specified in the Standard for Heat Actuated Fire Detectors for Fire Alarm Systems, CAN/ULC-S530;

d) Heat alarm requirements which are covered in the ULC-ORD 539, Single and Multiple Station Heat Alarms;

e) Carbon monoxide gas detectors intended for use in hazardous locations as defined in the International Maritime Dangerous Goods Code IMO 2006;

f) Residential carbon monoxide alarming devices, CSA 6.19; and

g) Standard for Gas and Vapour Detectors and Sensors, Including Accessories, CAN/ULC 588.

1.7 Except as indicated in 1.8, a component of a product covered by this standard shall comply with the requirements for that component. See Annex A for a list of standards covering components generally used in the products covered by this standard.

1.8 A component is not required to comply with a specific requirement that:

a) Involves a feature or characteristic not required in the application of the component in the product covered by this standard; or

1.9 A component shall be used in accordance with its rating established for the intended conditions of use.

1.10 Specific components are incomplete in construction features or restricted in performance capabilities. Such components are intended for use only under limited conditions, such as certain temperatures not exceeding specified limits, and shall be used only under those specific conditions.

1.11 Values stated without parentheses are the requirement. Values in parentheses are explanatory or approximate information