Watching over fire protection systems:
Many electrical contractors get frustrated because the fire alarm system they are responsible for installing is also interfaced with many other fire protection-related systems in the building; every fire protection system must be connected to the building’s fire alarm system. As with the fire alarm system, other fire protection systems must be ready when they are needed. By electrically supervising the operational status of the other systems, the owner can be assured it will be there when he or she needs them to operate.
In the everyday world of an electrical contractor, he or she gets service calls from customers. If a light does not work or a fan does not operate, the owner can wait until it is repaired; rarely are these problems life threatening. However, the loss of reliable operation of an automatic sprinkler system due to a closed valve or some other water-related issue, such as freezing, can be catastrophic.
Building codes, the Life Safety Code and insurance companies all require supervision of fire protection systems. Each of these entities requires that the fire protection system supervisory devices be installed in accordance with the National Fire Alarm Code.
The various conditions, systems or devices that must be supervised are as follows:
- Temperature monitoring (supervisory) —Water temperature —Room temperature
- Automatic sprinkler systems —Waterflow (alarm) —Closed valves (supervisory)
- Process monitoring systems (supervisory)
- Carbon monoxide detectors or carbon monoxide detection systems (supervisory)
- Fire pumps —Any supervisory signal indicating an abnormal condition requiring immediate attention
- Fire extinguisher monitoring devices and systems (supervisory)
- Kitchen hood extinguishing systems
- Gaseous suppression systems —System trouble (supervisory) —Gas discharge (alarm)
- HVAC smoke detection (alarm or supervisory)
- Water level (supervisory)
Each of these systems, if present in the building, is required to be monitored by the fire alarm system. The alarm condition is obvious; however, many contractors are unaware of what a supervisory condition means. NFPA 72-2007 defines supervisory signal as a “signal indicating the need for action in connection with the supervision of guard tours, the fire suppression systems or equipment, or the maintenance features of related systems.”
The installation of these devices is often by other contractors, but the interface to the fire alarm system is the electrical contractor’s responsibility. As you can see, not all of the signals are connected to the fire alarm system to initiate an alarm.
Typically, the suppression systems such as an automatic sprinkler system or a gaseous suppression system will initiate an alarm condition due to their importance in the life and property safety equation.
When it is important to ensure the operational reliability of a suppression system, then the fire alarm system will monitor specific parts that are key to its operation. For example, the most common system that electricians interface with a fire alarm system is the automatic sprinkler. There are a number of areas that may need to be monitored, including the status of the gate valve or post indicator valve that controls the supply of water to the system. The closure of these valves will initiate a supervisory signal at the fire alarm control unit and at the supervising station. A supervisory signal indicates that the automatic sprinkler system is impaired and will not operate properly when called upon. The intent of the signal is to call attention to the fact that the sprinkler system is impaired and needs service.
In an industrial setting, the water supply may be fed from a raised tank so a water level supervisory signal is very important. Should the water level be too low, then a supervisory signal must be initiated. The same holds true for a water supply in a temperature-controlled space that is to supply a dry sprinkler system in an unheated building. If the temperature drops in the heated space, putting the sprinkler water supply at risk, then a supervisory condition must be initiated.
As the professional contractor will determine from the above, the supervision of other fire suppression systems is an important aspect of a fire alarm system’s performance. The coordination of these interfaced supervisory devices and their proper installation also should take on a more important meaning as well.
Every electrical contractor involved in a fire alarm system installation should review all of the fire protection systems that are planned for the building he or she is working in. Once the other systems have been identified, it will be easier to ensure that they are properly interfaced to the fire alarm system and that the fire alarm system will watch over the other fire protection systems. 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.