Or, why you need a common sense approach to applying the code.
NFPA Journal®, November/December 2008
If you work in the fire alarm systems industry long enough, you’ll meet quite a few people who claim to have an almost photographic memory of the requirements of the NFPA 72®, National Fire Alarm Code®, and the ability to apply them strictly to every fire alarm system installation. But not every situation will allow the rigid application of the code to the letter. A facility’s unique circumstances may mean it does not neatly fit the literal language of the code. When this occurs, someone has to determine the "intent of the code." And that begins with the question, "Who provides the interpretation of the code’s intent?"
Often, the system designer will make an interpretation decision based on his or her background in fire protection. In most cases, that decision requires the authority having jurisdiction (AHJ) to review the specific issue at hand and provide an interpretation of the code’s intention.
As stated in Section 1.2.3 of the 2007 edition of the National Fire Alarm Code, "This Code establishes minimum required levels of performance, extent of redundancy, and quality of installation but does not establish the only methods by which these requirements are to be achieved." I added the emphasis to show that the NFPA 72 Technical Committee clearly understands that a designer or installer may use different methods to meet the intent of the code.
In addition, Section 1.5.1 of the 2007 edition of NFPA 72 states, "Nothing in this Code shall prevent the use of systems, methods, devices, or appliances of equivalent or superior quality, strength, fire resistance, effectiveness, durability, and safety over those prescribed by this Code." This section also requires that technical documentation "be submitted to the authority having jurisdiction to demonstrate equivalency."
Here, the code places the AHJ in the potentially difficult position of reviewing something that may be technically beyond his or her knowledge. Far too often, an AHJ will take the easy way out by refusing to approve something that may be perfectly acceptable.
The right decision almost always appears when all parties involved in the fire alarm system design and installation review the issue, based first on the impact on life safety and then on the long-term effects on system reliability, operation, and ease of maintenance.
For example, the code offers guidance for spacing smoke detectors. By treating the values as absolutes, some AHJs require installers to move a smoke detector placed at a spacing of 32 feet (9.8 meters) on center on a smooth ceiling back to 30 feet (9.1 meters) on center because "that’s what the code says!"
NFPA 72 tries to clarify that the stated spacing value of 30 feet (9.1 meters) on center never intended to express a listed spacing requirement, nor a value based on any actual research. Rather, the value represented a "fair and conservative" number. The code now states in Section 22.214.171.124.3.1 that, "In the absence of specific performance-based design criteria, smoke detectors shall be permitted to be located using 9.1 meters (30 feet) spacing." It then points the code user to the Annex where the technical committee adds that, "The 9.1-meter (30-foot) spacing is a guide for prescriptive designs. The use of such spacing is based upon customary practice in the fire alarm community…."
Section 126.96.36.199.3.3 further states that, "Other spacing shall be permitted to be used depending on ceiling height, different conditions, or response requirements."
The guidance allows the designer to propose—and the AHJ to approve—a spacing based on the conditions of the area being protected. Such a design decision has little or no impact on the life safety, so the AHJ should rightly approve the design.
A wise designer, installer, or AHJ will always start with a literal interpretation of each requirement. To move beyond the literal, seek help from other experts.
Wayne D. Moore, P.E., FSFPE, is a principal with Hughes Associates and immediate past chair of the NFPA 72 Technical Correlating Committee.