More homeowners want CO detectors installed

Smoke detection in the home has saved numerous lives and is now a normal part of every electrical contractor’s commercial installation package. However, carbon monoxide detector installations present a new opportunity for electrical contractors serving the residential market.

The danger of carbon monoxide poisoning has increased over the last few years. In fact, the Consumer Products Safety Commission (CPSC) reports that approximately 200 people per year are killed by accidental carbon monoxide (CO) poisoning with an additional 5,000 people injured.

The CPSC also reports that deaths due to carbon monoxide poisoning associated with heating systems jumped almost 60 percent from 1999 to 2000. Carbon monoxide is an odorless, colorless, tasteless and toxic gas that is produced as a by-product of combustion. Any fuel-burning appliance, vehicle, fires or other combustion devices produce dangerous levels of carbon monoxide gas. Examples of CO-producing devices commonly found in the home include: fuel fire furnaces, gas dryers, gas water heaters, unvented kerosene heaters, fireplaces, woodstoves, idling automobiles in attached garages, charcoal grills and yard equipment, such as snowblowers, lawn mowers, etc.

Usually the byproducts of combustion are safely vented to the outside. But when something interferes with the venting process, such as bird’s nests in the chimney or lint blocking a clothes dryer vent, CO production can quickly reach dangerous levels.

When CO is inhaled, it combines with the oxygen-carrying hemoglobin of the blood to form carboxyhemaglobin and, depending on how long this combination takes to build up, will determine the effects on the individual breathing the gas.

As outlined in NFPA 720-2003, Recommended Practice for the Installation of Household Carbon Monoxide (CO) Warning Equipment, “The effects of exposure to carbon monoxide vary significantly among different people. Infants, pregnant women and people with physical conditions that limit their body’s ability to use oxygen can be affected by low concentrations of carbon monoxide. These conditions include, but are not limited to, emphysema, asthma and heart disease, all of which are usually indicated by a shortness of breath upon mild exercise.”

Early exposure causes flu-like symptoms that gradually deteriorate to inability to walk and eventual death.

Next to maintaining fuel-burning appliances in good working order, carbon monoxide detectors provide the best defense against CO overexposure. There are three types of CO sensors presently on the market: metal oxide, biometric and electrochemical. CO detectors that use household current typically use a solid-state sensor that purges itself and re-samples for CO on a periodic basis. Although there are performance differences between these technologies, they all must meet UL 2034, Standard for Single and Multiple Station Carbon Monoxide Detectors.

The electrical contractors responsible for installing these devices should follow the guidelines of NFPA 720-2003, Recommended Practice for the Installation of Household Carbon Monoxide (CO) Warning Equipment.

NFPA 720 “contains recommendations for the selection, installation, operation and maintenance of equipment that detects concentrations of carbon monoxide that could pose a risk to the health of most occupants in family living units.” NFPA 720 also cautions that “although carbon monoxide warning equipment might respond to gases produced by unwanted fires, it is not fire warning equipment and should not be used in lieu of fire warning equipment required by NFPA 72, National Fire Alarm Code, or NFPA 101, Life Safety Code.”

The electrical contractor is advised by NFPA 720 to locate a carbon monoxide alarm or detector centrally “outside of each separate sleeping area in the immediate vicinity of the bedrooms and if the sleeping areas are separated and the audibility of the alarm or detector to occupants within each sleeping area could be seriously impaired, more than one unit could be needed.”

In general, because CO is close to the same weight as air and the gas distributes evenly throughout a room, a detector can be placed at any height in any location as long as it can be heard. NFPA 720 recommends that each alarm or detector should be located on the wall, ceiling, or other location as specified in the installation instructions that accompany the unit.

For electrically powered household carbon monoxide warning equipment, the primary (main) power source should be AC, unless powered by a monitored DC circuit of a control unit. The AC primary power source should be a commercial light and power supply or other dependable source.

Carbon monoxide alarms meeting the requirements of UL 2034, Standard for Single and Multiple Station Carbon Monoxide Detectors, and installed in accordance with NFPA 720 should provide a significant level of protection against fatal carbon monoxide exposure and CO detector installations also present a good opportunity to the residential electrical contractor to add to their profit margin. EC

MOORE, a licensed fire protection engineer, frequent speaker and an expert in the life safety field, is a co-editor of the current National Fire Alarm Code Handbook. Moore is a principal with Hughes Associates Inc. at the Warwick, R.I., office.