Security Business

MAY 2019

Find news and information for the executive corporate security director, CSO, facility manager and assets protection manager on issues of policy, products, incidents, risk management, threat assessments and preparedness.

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Page 32 of 83

May 2019 / / Security Business 33 set; allowing each pair set to have fully independent classification and power allocations. • Power disconnect – A PSE may disconnect power from a PD if no usage has been detected for 320 to 400 ms. The main reason for a class system is to enable power requirements to be negotiated for better management of the PSE’s power budget. A summary of power classes is illustrated in the chart on page 32. One installation concern is the potential heat build-up in a cable bundle as higher currents are pushed through the conductors. NFPA 70 (the National Electrical Code) in 2017 added section 725.144, Transmission of Power and Data, that for Class 2 and Class 3 circuits, details the maximum-allowable ampacity of cables based on the size of the individual conductors and the number of cables in a bundle. Further, Section 840.160 requires compliance with section 725.144 for PoE installations. A new Section 840.170 provides listing requirements for PoE power sources. Also, higher-current PoE systems may affect the conducting surfaces on RJ-45 connectors via electrical arcing during mating/demating. Arcing may lead to corrosion and pitting damage on the plated contact surface. Leviton has a good white paper on this topic at (look for the Connectivity for PoE article at the bottom) that recommends using connectors designed to minimize arcing effects, connectors and patch cords with 50 µm gold-plated tines (as specified by ANSI/TIA-1096-A and ANSI/TIA-568-C.2 standards), and metal connector bodies for better heat dissipation. Additionally, do not forget back-up power for PSE equipment to keep everything running, or consider local device power in the event of PoE failure. UPS systems will need to be rethought with these increasing demands. Electricians to Take Security Business? At the recent PSA-TEC, I shared a panel with NSCA Executive Director Chuck Wilson, who pointed out a battle in some states around who installs higher power PoE circuits. Some have begun to think that it is the province of electricians vs. low-voltage contractors. As the power needs of some devices have fallen (LED bulbs) while PoE has gone up, devices and equipment that were once electrical installs are now squarely in the sights of low-voltage contractors. That said, the promise of PoE is undeniable, and it will be most interesting to see new PSE and PD equipment introduced to take advantage of it. Copies of IEEE 802.3bt-2018 may be purchased through IEEE/Techstreet at ■ » Ray Coulombe is Founder and Managing Director of SecuritySpecifiers and the CONSULT Technical Security Symposium. He can be reached at, through LinkedIn at or followed on Twitter, @RayCoulombe. Solutions to Enhance Your Business • Fusion Monitoring • Disaster Recovery • Technology & Infrastructure Quick Response Your trusted partner 800-462-5353 Request information:

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