Fire Side Chat: What NFPA 720 Tells Us About CO Detection

The number of injuries and deaths due to carbon monoxide (CO) poisoning routinely increases every year as cold weather moves across the nation. The CO threat is an ever-present danger to humankind and animals. This is especially true during the winter months when it becomes necessary to use combustible heating, such as fireplaces and gas- and oil-fired furnaces.

When exposed to excessive levels of CO, the body’s red blood cells essentially lose the ability to carry oxygen. As the oxygen level in the bloodstream drops, so does an individual’s ability to think rationally. At some point if this condition is not alleviated, listlessness and unconsciousness can result. In due time, damage to the brain can occur.

Alarm dealers that service residential and commercial fire alarm systems are in an ideal position to raise the awareness of their customers to the CO threat. The objective is to sell them a CO package and add it to their existing alarm system. Unfortunately an upsell is especially easy to do when there’s a high-profile CO death locally.

Because of the threat that CO poses, the National Fire Protection Association (NFPA) has developed a standard that addresses detection in both a systems environment and in standalone mode. This document is designated as NFPA 720 and the code is titled, “Standard for the Installation of Carbon Monoxide (CO) Detection and Warning Equipment.”

This month, we’ll take a closer look at NFPA 720. Keep in mind that although 720 is similar to NFPA 72 in some respects, there are differences. It’s also extensive enough that we’ll only cover the highlights this month.

CO Equipment Requirements

Like any life-safety device, CO detection equipment must be listed for that purpose by an impartial, third-party laboratory, but only after extensive testing.

“Equipment constructed and installed in conformity with this standard shall be listed for the purpose for which it is used. [Carbon monoxide detection] system components shall be installed, tested, and maintained in accordance with the manufacturer’s published instructions and this standard” (Section, NFPA 720, 2009 Edition).

Just like a common fire alarm panel, the fire technician must make two power sources available for the systems to detect CO: primary and secondary. According to Section, “At least two independent and reliable power supplies shall be provided, one primary and one secondary, each of which shall be of adequate capacity for the application.”

The control panel to which a CO detector interconnects usually provides primary power. This power is most often generated by a low-voltage power supply contained within the control panel itself. Code requires that primary power come from a dedicated circuit that, much like a fire alarm panel, must be identified so the end user knows where it is in a breaker box. It also should be protected from physical harm using conduit or some other means.

Secondary power is more often generated by one or more rechargeable batteries contained inside a control panel or separate power supply. When a CO detection system is part of a combination system, battery capacity must comply with both the appropriate code as well as

According to Section, NFPA 720, battery capacity must be capable of providing 24 hours of standby in nonalarm mode with a subsequent 12 hours of operation under full load, which includes use of all notification devices. The exception is when the CO system in question is monitored, in which case the 12-hour requirement can be reduced to 60 minutes.

Both sources of power must be supervised and outages reported to a central station in much the same way a common, ordinary fire alarm control panel does. NFPA 720 calls for the use of a digital alarm communicator transmitter (DACT) for this purpose.

Unified, Code-Compliant Alerting

In order to understand the specifics associated with CO detectors and notification appliances, it’s important to define the purpose of a CO system under NFPA 720. According to Section 4.2, “The purpose of carbon monoxide detection systems shall be primarily to provide notification of carbon monoxide, and trouble conditions; to alert the occupants; and to summon aid.”

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About the Author


Shane Clary, Ph.D., is Security Sales & Integration’s “Fire Side Chat” columnist. He has more than 37 years of security and fire alarm industry experience. He serves on a number of NFPA technical committees, and is vice president of Codes and Standards Compliance for Pancheco, Calif.-based Bay Alarm Co.

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