Fire & LIfe Safety: Melding Cameras with Fire Detection

Video Image Smoke Detection (VISD) continues to advance thanks to the latest in camera technology. It wasn’t so long ago that smart camera systems were only able to detect movement in certain zones assigned to their field of view; and until relatively recently, outdoor camera operation required masking of areas to prevent tree branches and cars from activating the alarm.

The advent of smart camera systems provided continuous recording of the entire scene, but no one was notified (i.e. alarm) unless motion was detected. Once facial-recognition software became commonplace, application of this same technology to smoke and fire detection was not another leap forward — it was a step sideways into another market.

Now, outdoor smoke and fire detection devices can be provided with infrared illumination so these VISD cameras can provide protection, yet still allow lights to be turned out in unoccupied spaces. Smoke/flame detection cameras have always had local alarm and trouble features, but now they have also gone IP and can provide offsite visual verification of alarms.

Technology has the ability to multiply its value when applied to different platforms, but it is the salesperson’s job to convey this technological value to their prospects. Today you can help a client justify the purchase of new video cameras by demonstrating to them that not only will they benefit from all the additional bells and whistles a new video surveillance system will afford them, but their facility will also benefit from improved fire and smoke detection in large open spaces — spaces where traditional spot-type smoke and heat detectors cannot provide the same advanced warning.

If you haven’t investigated VISD or VIFD equipment, you owe it to your company’s bottom line to do so.


Duct Detection Follow-Up

My recent column on duct detectors (in the July issue of SD&I; article available at generated a few additional questions. If you found it hard to believe that duct detectors do not always need battery backup and that they do not have to always be an integral part of the fire alarm system, consider the following two scenarios:

When duct detectors are not supplied by the fire alarm system company: The Mechanical Code requires duct detectors; and they are usually supplied by the HVAC contractor, who may order factory-installed, AC-powered duct detectors or order them separately from an HVAC manufacturer and install them as needed. If the HVAC unit has no power, then there is no operating fan for the duct detector to shut down, and therefore, no reason to supply backup power to just the duct detector.

HVAC systems do not normally need standby power, so codes and standards do not require duct detectors to have it. In the extremely rare instance where HVAC units are connected to standby generators, the same standby generator power is likewise supplying AC power to the duct detectors.

When duct detection is supplied by the fire alarm system company: It is possible for the FACU or auxiliary power supply to power the 24vdc duct detector from the auxiliary terminals and still provide no standby power, and be considered an “integral part of the fire alarm system.” This is also common with magnetic door holders.

Sometimes it is desirable for the FACU to provide supervised, standby power when system-type detectors or addressable system-type detectors are used. If the owner/contractor chooses to supply system-type detectors instead of using the factory installed AC detectors, then the duct detectors will be powered by the FACU should the alarm installation company/building owner choose this option.

If the HVAC unit and its duct detector are powered separately, the power to the detector must be supervised by the alarm system, allowing the HVAC unit to continue to operate without the possibility of shutting down the fan if smoke is detected, thus they would still be considered an “integral part of the fire alarm system.” Regardless, battery backup is not a requirement. The codes and standards allow AC-powered duct detectors to be used, and only stipulate that they cause a supervisory signal to be seen and heard somewhere should they activate.

NFPA 72 ( allows for devices that are an “integral part of the fire alarm system” to drop standby power during primary power outages. The only reason duct detectors must be supervised by a fire alarm system — and only when it is a code-required fire alarm warning system — is to provide better annunciation then the HVAC contractors who provide placards that read, for example, “RTU #7” or “AHU #14”, when they are supposed to indicate the location of the detector and area served by the air handling unit. It is for this reason only, that the fire alarm company gets involved with these mechanical systems. Monitoring the duct detector’s contacts for a supervisory signal is the (only) stated requirement.


Greg Kessinger is SD&I’s resident fire alarm and codes expert and a regular contributor. Reach him at