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-S531;
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-S529;
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-C539, 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-S588.
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
b) Is superseded by a requirement in this standard.
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.
CAN/ULC-S538:2020 history
2020CAN/ULC-S538:2020 STANDARD FOR SINGLE AND MULTIPLE STATION CARBON MONOXIDE ALARMS FOR NON-RESIDENTIAL APPLICATIONS