The primary code for any electrician is the National Electrical Code (NEC), and information about it appears regularly in this magazine to help ensure you are kept up-to-date with all the changes and understand the impact on your everyday business.
Technology changes so rapidly that even those of us dedicated to the field of fire alarm systems often find it challenging to keep up with changes brought by the Underwriters Laboratories, other code-making bodies, and manufacturers.
On Aug. 17, 2006, the 2007 National Fire Alarm Code was approved by the NFPA Standards Council and became an American National Standard. Significant changes include fire alarm control unit protection, the way alarm signals are deactivated, installation for smoke detection in ducts, those addressing new sensor technology, synchronization of visible notification appliances, smoke detector spacing, and the addition of different types of protected premises fire alarm systems and in-building enhancement systems for firefighter radio systems.
Changes to chapter 11 required smoke alarms in existing buildings and revisions to require additional smoke alarms for larger residential dwelling units.
The code allows for the deactivation of fire alarm signals and contains the specific requirements in section 18.104.22.168. In the past, many systems were designed so when the audible alarm signal was silenced, the visible signal would be required to continue to operate. No one in the industry is really sure where this “policy” came from, and it was never a code requirement.
NFPA 72-2007, section 22.214.171.124.2 now states, “When an alarm signal deactivation means is actuated [that is when the alarm silence switch is placed in the silence position], both audible and visible notification appliances shall be simultaneously deactivated.” The annex material explains in A.126.96.36.199 that it “is the intent that both visual and audible appliances are shut off when the signal silence feature is activated on the fire alarm control unit. Per the ADA, it is important not to provide conflicting signals for the hearing impaired.”
How does this affect the electrical contractor? With most manufacturers, in order to comply with the previous “policy” to leave the visible signals operating, two separate feeds were required to the audible/visible appliance, two conductors for the audible alarm and two for the visible alarm appliance. If an EC comes across a specification using this operation method, he or she would be wise to point out the new code requirement to the engineer of record and the authority having jurisdiction (AHJ). Compliance with the 2007 edition for this one issue may save a significant amount of money in cable and conduit costs.
The changes in the protection of fire alarm control units are another issue that can be important to the contractor. The new requirements are contained in section 4.4.5 of the new code. Specifically, the code requires that in “areas that are not continuously occupied, automatic smoke detection shall be provided at the location of each fire alarm control unit(s), notification appliance circuit power extenders, and supervising station transmitting equipment to provide notification of fire at that location.”
The annex material explains that “fire alarm control unit(s) that are to be protected are those that provide notification of a fire to the occupants and responders. The term fire alarm control unit does not include equipment such as annunciators and addressable devices. Requiring smoke detection at the transmitting equipment is intended to increase the probability that an alarm signal will be transmitted to a supervising station prior to that transmitting equipment being disabled due to the fire condition.”
Previously, the code required only a smoke detector at the control unit. There are some important exceptions. Automatic heat detection can be used where ambient conditions prohibit the installation of automatic smoke detection. Also, the smoke detection is not required at all in fully sprinklered buildings.
The annex continues, “where total smoke-detection coverage is not provided, the code intends that only one smoke detector is required at the control unit even when the area of the room would require more than one detector if installed according to the spacing rules in Chapter 5. The intent of selective coverage is to address the specific location of the equipment.
“Location of the required detection should be in accordance with one of the following:
1. Where the ceiling is 4.6 m (15 ft.) in height or less, the smoke detector should be located on the ceiling or the wall within 6.4 m (21 ft.) of the centerline of the fire alarm control unit being protected by the detector in accordance with 188.8.131.52.1.
2. Where the ceiling exceeds 4.6 m (15 ft.) in height, the automatic smoke detector should be installed on the wall above and within 1.8 m (6 ft.) from the top of the control unit.”
Both changes can affect the bottom line of new projects, and the EC would be wise to ensure the project manager is aware of the new requirements and their impact on a fire alarm system installation project. 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. and is located at the Warwick, R.I., office.