A wide range of safety extra low voltage (SELV) limited power source (LPS) applications may be supported using remote power deployed over balanced twisted-pair cabling.  Examples of these types of applications include LAN devices supported by IEEE Std 802.3™ PoE (DTE Power via MDI), wireless access points, TIA-862-B building automation systems, PoE lighting, and security devices such as remote cameras, IP telephones, and multimedia devices.

TSB-184-A “Guidelines for Supporting Power Delivery Over Balanced Twisted-Pair Cabling” was developed by the TIA TR-42.7 Copper Cabling Subcommittee and published in March, 2017. This Telecommunications Systems Bulletin  provides guidelines to enable the support of a wide range of safety extra low voltage (SELV) limited power source (LPS) applications using remote power supplied over balanced twisted-pair cabling. This TSB also describes methods to help manage temperature rise within cable bundles due to dissipation of power.

Significant changes from the previous edition include:

  • Maximum applicable current has been increased to up to 1000 mA per pair
  • Temperature rise models have been refined to include additional cable properties and installation conditions
  • Temperature rise tables include temperature rise in open air and sealed conduit
  • Bundling recommendations and installation recommendations have been added
  • Measurement procedures to develop temperature rise models have been refined and included in the document
  • Additional specifications for pair-to-pair dc resistance unbalance have been added

TSB-184-A Content

  • Configuration, Structure, and Topology
  • Cabling Selection and Performance
  • Installation Guidelines
  • DC Resistance
  • Remote Powering Configurations and Related Transmission Performance
  • Annexes addressing Cabling Types and Installation Guidelines for DC Powering, Models, and Measurement Methods

Recommended Cabling

  • Category 6A or higher performing 4-pair balanced twisted-pair cabling is recommended for new installations delivering remote power
  • Thermal dissipation can be improved by selecting cables with:
    • Improved thermal conductivity
    • Improved heat transfer coefficient between cable materials
    • Improved heat transfer coefficient between cable jacket and air
    • Metallic elements (e.g. shield, screen)
    • A larger diameter
  • Connecting hardware having the required performance for mating and un-mating under the relevant levels of electrical power and load (e.g. compliant to the test schedule described in IEC 60512-99-002 for engaging and separating connectors under electrical load) should be chosen

Bundling Recommendations

  • Cables should be left unbundled to allow for improved heat dissipation
  • A way to limit the temperature rise due to conditions such as installation factors, possible high ambient temperature, the use of 26 AWG cords, and higher currents up to 1000 mA per pair with all four pairs energized, is to limit the number of cables per bundle to 24 in typical pathway installation conditions
  • If bundling is necessary, it is recommended to separate large bundles into smaller bundles

Maximum Cable Bundle Size for 15 °C Temperature Rise at 20 °C Ambient

Click here for archive information on TSB-184.

Sorry, the comment form is closed at this time.

© 2017 Standards Informant Suffusion theme by Sayontan Sinha