Pushing Distance Limitations for Security Cabling

Pushing beyond the 100 meters

The industry standards that govern structured cabling installation practices were originally written for data and voice applications. However now that disparate devices, previously run on proprietary systems, such as security, access points  and building automation devices, are jumping onto the network, some of the standards’ recommended guidelines for premises installations are under scrutiny.

One of the biggest limiting factors in the industry standards is the 100-meter (328-foot) limit from end-to-end of the horizontal UTP/FTP cabling system. To understand why Ethernet is limited to 100-meters over copper, it dates back to the origins of the standard.   Dave Hess, Nexans technical manager, who has served on TIA, and ISO/IEC cabling committees, recently explained this in an article in BICSI News (Jan/Feb 2010), “Ethernet originally evolved from DEC, Intel and Xerox.   StarLAN™ by AT&T was actually the first implementation of Soon after, AT&T broke up and their premises cabling became public domain and their technical specifications became the foundation for the TIA standards for 10 Mb/s. The 100-meter limitation was approved into the first 568 standards because many of the committee members, which included architects and designers, agreed that from a telecommunications closet to a device, 100 meters should reach every point on a normal building floor. If not, then another closet would be needed. As IEEE standards evolved to one gigabit, the 100-meter limit stands and twisted pair cable remains backwards compatible. Anything farther than that would fall under the definition of fiber optic channels.”
 
Because video over Ethernet is actually data in digital form, the same rules apply. Analog cameras can run further than 100 meters over twisted pair with transceiver technology, but those locations will never be standards’ compliant and therefore, cannot be replaced with IP cameras. And  running fiber optic cable out to coax-based analog cameras means deploying multiplexers, which can get very costly per channel. 
 
 
Composite Copper/Fiber
 
Berk-Tek’s New Composite Copper/Fiber Cable Extends the Distance
 
Distances from the TR to the end device can be extended by using fiber as a cost-effective solution. IP cameras already have built-in Ethernet ports and with cost-effective media converters can utilize fiber optic cable push out to several thousand feet beyond the copper distance.
 
Berk-Tek recently introduced a composite copper/fiber cable that incorporates high-bandwidth optical fibers with up to seven insulated stranded THWN (Thermoplastic Head and Water Resistant, Nylon coated) conductors ranging from 12 to 20 AWG under one outer jacket.   Ethernet runs the data over the fibers and power is run over the copper conductors. So, in essence, this cable increases the distance of Power over Ethernet (PoE and PoE Plus) to deliver power to the device, eliminating an electrical outlet. 
 
The cable is listed as CL3R-OF (Class 3 Riser with Optical Fiber) and PLTC-OF (Power Limited Tray Cable with Optical Fiber) and meets Article 725 of the NEC to allow a common pathway for both communications and control (Class 2 and Class 3 power supplies). One pathway, one pull, one solution.  
 
The cable is offered with tight buffered or loose tube fibers. The tight-buffered cables are available with up to 12 fibers and can be broken into subunits --  individually jacketed fibers for HDR (Heavy Duty) or grouped fibers for PDR (Premise Distribution) applications. The loose-tube design is based on Berk-Tek’s patented Adventum™ with up to two tubes, each containing 12 fibers each. Both the tight-buffered and loose-tube cables are available with Berk-Tek’s DryGel™ water-blocking technology for indoor/outdoor applications. A gel-filled loose tube version is also available for outside plant environments (OPR).
 
This cable can be constructed with all types of Berk-Tek fiber – from single-mode to multimode (62.5µ OM1  to 50µ laser-optimized GIGAlite™ fiber for OM4). However, since many of these end devices operate at data rates below 100 Mb/s, OM1 or OM2 fibers will most likely be the cost-effective choice.
 
There are media converters on each end of the cable to convert the Ethernet signal from electrical to optical and then back again through an RJ-45 patch cable which plugs in directly to the device. The total distance of the composite cable is limited by the voltage drop of the copper conductors. The combination of the amount of current that the device draws and the resistance of the conductors, which is factored by the gauge size, determines the amount of voltage lost. By selecting a larger gauge of cable (12 AWG) will allow PoE at 1,170 meters (3,850 feet) and PoE Plus devices at 760 meters (2,500 feet).
 
Berk-Tek’s composite cable will be demonstrated at the BICSI Winter Conference (January 17-21) with a live security camera video feed between Berk-Tek’s Booth 1124 and Panasonic’s NVR in their booth #1128.

Your Contact

Carol Oliver Berk-Tek Marketing Analyst
carol.oliver@nexans.com