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Are You Installing the Right Carbon Monoxide Detector?

When security dealers, installers and distributors are evaluating which carbon monoxide (CO) detector to purchase, they should look for a product that is listed for the intended use and features that comply with the industry’s most recent product standards. Every alarm professional should understand the differences between American National Standards Institute (ANSI) and Underwriters Laboratories (UL) standards ANSI/UL 2034 and ANSI/UL 2075 and be aware of the new requirements of the third edition of ANSI/UL 2075 that become effective later in 2009.

The CO detection market has seen significant growth in the last few years driven by legislation requiring the installation of CO detectors in single/two-family dwellings and commercial occupancies such as hotels, child and adult day care and university dormitories. Currently, there are 21 states and many major municipalities that have CO regulations.

ANSI/UL 2034, Single and Multiple Station Carbon Monoxide Alarms, is the product standard for self-contained CO alarms. These alarms are not designed nor are they listed to be connected to an alarm control panel. They receive their primary operating power from: a battery in the unit, a plug-in unit that uses a two- or three-prong attachment plug or a unit that is wired into the dwelling’s AC power line with secondary power backup.

ANSI/UL 2075, Gas and Vapor Detectors and Sensors, is the product standard for CO detectors that are designed and listed to be connected to an alarm control panel (system-connected) via conductors extending from the detector to the control panel or low-power radio frequency signal. It is important to note that even though there are two standards for CO detection devices they both have the same alarm thresholds. ANSI/UL 2075 requires detectors to operate within the sensitivity parameters defined in ANSI/UL 2034. The alarm thresholds are:

  • 70 ppm 1 to 4 hours (but not less than 1 hour)
  • 150 ppm 10 to 50 minutes
  • 400 ppm 4 to 15 minutes

All system-connected CO detectors manufactured after September 1, 2009, will be required to meet the new requirements of the Third edition ANSI/UL 2075. Therefore, hardwired CO detectors that have the UL 2075 mark and are manufactured prior to September 1, 2009, may not be compliant with the new product standard.

Several new requirements of ANSI/UL 2075 mandate critical life safety supervision features that will prevent a failed detector from going undetected. These new requirements are fundamental concepts of all life safety products, such as fire alarm system devices and central station service.

There are currently three different gas sensing technologies on the market: biomimetic, metal oxide semiconductor (MOS) and electrochemical. All three gas sensing technologies have a limited life, therefore, it is imperative that the gas sensing element be supervised in order to ensure continuous operation. The new ANSI/UL 2075 mandates the detector to electrically supervise the gas sensing element so that when the sensor reaches its end-of-life (EOL), the detector will send a trouble signal to the control panel. This new electrical supervision requirement of the carbon monoxide sensing element is vital for safe and effective performance of the detector. To be compliant with ANSI/UL 2075, life-safety professionals should ensure their chosen system-connected CO detectors incorporate an integral trouble relay that sends a trouble signal to the control panel when the CO sensor has reached its EOL.

After September 1, 2009, the terminal screws of a system-connected CO detector must facilitate the required wiring supervision provisions of the UL standard. ANSI/UL 2075 requires the terminal screws to consist of binding screws with terminal plates having upturned lugs (see diagram). This method prevents the conductor from being wrapped around the terminal screw and requires the interruption of the wiring continuity when connection to the detector is lost. CO detectors that have pigtails are not acceptable.


The new requirements will benefit the alarm industry by improving the performance of detectors but more importantly will enhance life safety for the public in the years to come.

Carbon Monoxide Deaths Lead to Legislative Action

The investigation of the deaths of the Lofgren family vacationing in Aspen, Colo., in 2008 due to carbon monoxide (CO) poisoning have come to a close, according to a recent report from the Aspen Daily News Online.  District Attorney Martin Beeson filed a motion on April 1st to convene a special grand jury to decide who, if anyone, will be prosecuted for the CO poisoning death of a vacationing family in an Aspen area home in November. A faulty pipe in the heating and snow melt system leaked CO and killed the family while they slept, according to investigators.

In other headlines, two men and a 13-year-old boy in Minneapolis died from CO poisoning when they used a gas-powered generator in their basement after their power was shut off. In addition, a mother and two teens in Paramount, California, suffered CO poisoning in November when they heated their home with a charcoal grill.

CO detection is now more important then ever, as The Centers for Disease Control reports that cases of CO poisoning have been on the rise in recent years, climbing 36 percent between 2001 and 2006. A key cause is most evident in the winter months, when many families cannot afford to pay for electricity and eventually get their heating turned off. Using other sources of heat, families don’t realize the increased dangers of CO poisoning.

Thanks to the National Fire Protection Association (NFPA), the new edition, NFPA 720-2009 standard will be issued in October and will be the standard for the Installation of CO detection and warning equipment. It is the first CO standard to address CO devices in non-residential buildings and also mandates the placement of CO detectors/alarms on every level of a residence. The standard has been completely rewritten to encompass more types of occupancies and to specifically define CO detection usage.

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