Historic occurrences and their impact on NFPA 72
NFPA Journal®, September/October 2011
Major events such as the terrorist attacks on Khobar Towers in 1996, the terrorist attacks on the World Trade Center and the Pentagon on September 11, 2001, and the shootings at Virginia Tech in 2007 have all had an impact on the NFPA code-making system, resulting in new requirements that appear in the 2010 edition of NFPA 72®, National Fire Alarm and Signaling Code®.
One example is that, for the first time, NFPA 72 now allows another emergency signal to take precedence over a fire alarm signal. Chapter 23, Protected Premises Fire Alarm Systems, of Section 18.104.22.168 states that "Fire alarm signals shall have priority over all other signals." A clarification to this rule in Chapter 10, Fundamentals, states that "Fire alarm signals shall take precedence over all other signals, except as permitted by 10.6.1 or 10.6.3." Section 10.6.1, pertaining to emergency communications systems, notes that "ECS priority signals when evaluated by stakeholders through a risk analysis in accordance with 22.214.171.124 shall be permitted to take precedence over all other signals." More specifically, Section 10.6.3 states that "Emergency mass notification signals and messages shall be permitted to have priority over fire alarm notification signals in accordance with the requirements of Chapter 24."
This change to the code has come about because it was recognized that mass notification messages could become more important than a fire alarm signal to the occupants of a building or area. Further, the Technical Committee on Emergency Communications Systems, which is responsible for Chapter 24, has developed clear direction requiring that the fire alarm system will not automatically override emergency mass notification messages. To permit the override of a fire alarm signal, however, the stakeholders must conduct a risk analysis.
The annex of Chapter 24 offers additional guidance, stating that "the risk analysis should identify what emergency situations will take priority over the fire alarm evacuation signal." For example, "...Should a tornado warning for the area take priority over an active fire alarm in the building? Should a breach of security at the campus entry gate take priority over an active fire alarm in the building? If a manual fire alarm pull box has been activated, it might be a terrorist action to have people leave the building and walk outside to an exterior threat." Other examples where the fire alarm signal could be overridden include a terrorist threat or a shooter in the area or building. In each of these cases, the mass notification input may override the fire alarm evacuation signals to redirect the occupants based on the actual conditions, which may prove more dangerous to them.
In the Khobar Towers, 9/11, and Virginia Tech examples, the sites of the incidents did not have mass notification systems, which meant that the occupants did not have the flexibility of receiving prompt evacuation warnings. Before these incidents, the code did not permit other signals to override the fire alarm signal.
Although the technical committees cannot foresee every event the code might need to cover, we can learn from historical events and make the necessary changes. In addition, the technical committee can add individuals with unique experiences outside the traditional fire alarm arena to help them in the development of proper code language for the new scenarios. When this happens, all users of the code will benefit.
Wayne D. Moore, P.E., FSFPE, is a principal with Hughes Associates.