Selecting the Right Pair

Making the most of copper twisted-pair recommendations

When it comes to choosing cabling infrastructure for security, it is essential to work with a distribution partner that can provide the right education, training and products for your project needs. In a modern physical security network, each camera or access door controller should be viewed as a data point and not just a security node on the network. Using high performance structured cabling allows a range of devices from IP-based systems to serial devices to be interconnected.

For example, a camera connected to an equipment outlet can be easily replaced with a wireless access point or intelligent lighting as the application requirements of an organization change over time. By reconfiguring the physical security network for data points instead of specific applications, users can create a network infrastructure with a longer life cycle, more flexibility and greater scalability to meet shifting demands and to accommodate new technologies.

Likewise, designers for wireless data networks, DAS systems, voice systems and other IP-based systems look to create infrastructure networks that could support IP security devices. To have a fully supportable Internet Protocol (IP) network solution, it is becoming increasingly important to make the right choices up front when considering the structured cabling and components.

Users can protect network investments by matching the cabling infrastructure to its components based on the organization’s technical and life-cycle requirements to support current and future applications. The two primary choices for cabling infrastructure to support an IP-based system are balanced copper twisted-pair and fiber optic cabling. Some recommendations for designing a robust copper twisted- pair infrastructure follow.

CABLING REQUIREMENTS

Over time, the cost of replacing electronic hardware increases with technology advancements whereas high-quality, existing cabling infrastructures can be expected to support these future changes. The right cabling installation can be expected to last up to 20 years; however, many security products only last up to five years due to either obsolescence or feature revision preferences from the end user as needs change. Therefore, it is recommended to install at least a Category 6 cabling infrastructure to meet any future requirements.

UNSHIELDED TWISTED-PAIR AND SHIELDED TWISTED-PAIR OPTIONS

Due to its affordability and ease of installation, twisted-pair cabling is often the choice for security cabling infrastructure today. Unshielded twisted-pair (UTP) cabling is by definition manufactured without a shield on either the outer jacket or wire insulation. UTP uses a balanced pair design to reject noise that affects data transmission. In contrast to UTP, shielded twisted-pair cabling (F/UTP or S/FTP) has a different set of installation and maintenance rules due to the foil and/or braid shield used in its design.

In a shielded solution, all cables, patch cords and connecting hardware are manufactured with an added metallic shield element to further reduce potential electromagnetic interference (EMI) that could get coupled onto the transmission line. The metallic shield must be grounded to the telecommunications grounding system to ensure its performance, which requires additional installation materials, tools and procedures. However, in areas that have high levels of EMI, such as a manufacturing floor, this is the recommended solution because of the high prevalence and risk of EMI.

BACKWARD COMPATIBILITY

All cabling compliant to the standards of the Telecommunications Industry Association (TIA) or International Organization for Standardization (ISO) is backward compatible with the lowest component dictating the performance. An end-to-end channel is only as good as its weakest link. For example, mixing the performance ratings, or Categories, of cables, connectors and patch cords can negatively affect network performance by increasing the potential of IP equipment transmission errors, resulting in video quality degradation.

This is largely due to the fact that IP-based video depends on best effort delivery protocol (UDP) for delivery of the video data throughout the network and is very sensitive to transmission errors that manifest themselves on the network. Because information is dropped if data packets are received in error, this could cause significant degradation in the video that is viewed on the network.

POWER OVER ETHERNET SUPPORT

The delivery of DC power over twisted-pair cabling using the Ethernet protocol, also known as Power over Ethernet or PoE, is supported over the same copper cable infrastructure that supports the production network device applications.

When looking to use PoE, there are important factors to consider:

  • Today, up to 25 watts of power can be delivered to PoE-compliant devices on Category 5e and above cables using IEEE 802.3at compliant equipment.
  • A new version of PoE over twisted-pair cabling is being developed by the IEEE 802.3bt Task Force and is expected to deliver up to 70 watts to compatible equipment. With the increase in available power, it becomes even more important to specify cable constructions with larger conductor sizes such as Category 6 and Category 6A to mitigate potential heat effects on bundled cables.
  • Higher power over a bundle of cables has the potential to generate greater heat dissipation on each cable within the bundle. Heat will attenuate (i.e. insertion loss) a data signal, and in some cases, it can degrade the signal enough to cause network errors and therefore degrade video quality.

This article originally appeared in the September 2017 issue of Security Today.

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