Being Safe and Doing it Right

After addressing the lighting and exterior area of the premises last month, this month’s article concentrates primarily on internal security of the building, using Article 708 covering critical operations power systems (COPS) in the 2008 National Electrical Code (NEC). The provisions of this article apply to the installation, operation, monitoring, control and maintenance of the portions of premises wiring systems intended to supply, distribute and control electricity to designated critical operations areas (DCOA) in the event of disruption of the normal system. Normal systems include, but are not limited to, power systems; heating, ventilating and air conditioning (HVAC); fire alarm; security; communications; and signaling for the DCOA. DCOA is defined as an area within a facility or site designated as requiring COPS. Tied into the DCOA is Supervisory Control and Data Acquisition (SCADA). Keeping all of the acronyms straight may be half the battle in understanding the requirements in Article 708.

SCADA is referenced in Fine Print Note No. 8 within the scope statement in 708.1 and is an important part of any electronic system installed within a critical power installation. Article 708.2 defines SCADA as “an electronic system that provides monitoring and controls for the operation of the critical operations power system. This can include the fire alarm system, security system, control of the HVAC, the start/stop/monitoring of the power supplies and electrical distribution system, annunciation and communication equipment to emergency personnel, facility occupants and remote operators.” As can be seen in the definition of SCADA, security systems are an important part of the electronic systems in COPS and must be protected.

Security systems in critical power areas must comply with Section 708.5, which requires physical security be provided in accordance with 708.5(A) and (B). Section 708.5(A) requires a risk assessment to develop a strategy for providing physical security for these power systems, and this strategy must be documented and then implemented appropriately. In addition, 708.5(B) requires electrical circuits and equipment for critical operations power systems to be accessible to qualified personnel only. This fits well with the strategy of most security system operation. Section 708.10 requires COPS branch-circuit wiring, such as the branch-circuit supply to the security system installed outside the DCOA, to comply with the physical and fire protection requirements of 708.10.

Section 708.10(C)(1) through (C)(3) requires rigid metal, intermediate metal conduit or MI cable. In addition, the following wiring methods are permitted to provide protection for branch circuits supplying the security system where encased in not less than 50 mm (2 in.) of concrete: Schedule 40 or Schedule 80 rigid polyvinyl chloride conduit (Type PVC), reinforced thermosetting resin conduit (Type RTRC), electrical metallic tubing (Type EMT), flexible nonmetallic or jacketed metallic raceways, or jacketed metallic cable assemblies listed for installation in concrete. Where flexibility is an issue, flexible metal fittings, flexible metal conduit with listed fittings and liquidtight flexible metal conduit with listed fittings also can be used. The requirements within the DCOA are relaxed to permit any of the wiring methods recognized in Chapter 3 of the NEC, as the area already is secure with few physical protection issues.

Building-security planning for these facilities requires a survey of accessible doors, windows, ladders, exterior fire escapes, skylights, elevators, large HVAC systems and penthouses on rooftops that provide access into the building. Door and window hinges should be located inside the building and should be made secure by welding the pins and screws holding the hinges into the frames. Security windows in any doors should be shatterproof and small enough to prevent an intruder from passing through. Doorframes and window frames should be constructed of steel that would not permit easy access by doorframe removal.

Once building access points are identified, a security system can be installed, providing protection for the interior of the building. An alarm panel should be chosen that provides the proper number of protection zones based on the size of the building, the number of access points that must be protected, plus any additional desired security functions. Perimeter protection can be provided for all openings on the exterior of the building. Magnetic switches can be installed at doors, windows and other access points. Windows can be connected to vibration detectors, conductive metal foil or special detectors, such as glass break sensors that alarm from the sound of breaking glass in windows. Internal security doors also may require card readers, eye scanners and fingerprint access. Obviously, the larger and more complex the building, the more complex the security system must be for full security coverage.

ODE is a staff engineering associate at Underwriters Laboratories Inc., in Research Triangle Park, N.C. He can be reached at 919.549.1726 or at

About the Author

Mark C. Ode

Fire/Life Safety Columnist and Code Contributor
Mark C. Ode is a lead engineering associate for Energy & Power Technologies at Underwriters Laboratories Inc. and can be reached at 919.949.2576 and .

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