Can your Installation take PoE?

050.6212What is happening
Structured copper cabling for local data networks is constantly having to meet new demands. Initially, it was only used for connecting communication and data devices. Nowadays, however, a growing number of vastly differing end devices depend on LAN:

  • More stable WiFi connectivity is required to meet the needs of smartphones and tablets. Access points with a 5 GHz frequency range make greater demands of the cabling.
  • Structured cabling also requires increased agility to deal with the rising number of security systems.
  • Many of these new applications require more than 1 Gigabit Ethernet.
  • In addition, devices operated via Power over Ethernet (PoE) are becoming increasingly popular as a way to eliminate the need for additional low-voltage cabling.

Good to know
It could be problematic for many old Cat. 5e / Cat. 6 installations to deal with future interferences. Alien crosstalk can have an impact on unshielded (UTP) cabling in particular. In the past, the alien crosstalk factor was not taken into account during installation.

R&M issues the following recommendation: Check the installation and have it re certified before you upgrade the Ethernet technology. The relevant parameters can be found in the standard IEEE 802.3bz.

Today’s new installations should be planned at Cat. 6A level. Correctly installed Cat. 6A cabling offers reserves for the 2.5 and 5 Gigabit era and for the later use of 10 Gigabit Ethernet.

With PoE too, the focus is on the vastly increased performance to supply an ever increasing number of end devices with electricity over the data network. This is why PoE should increase to almost 100 Watts and run over all four pairs of wires. The impact of cable heating on data transmission performance must not be overlooked:

  • Whether existing installations are compatible with the higher PoE output and have an adequate loss budget depends on the cable and the planning.
  • Shielded cables and larger conductor cross-sections do not heat up as much.
  • The size of the cable bundle and the installation environment play a role.
  • If high currents are pending, the quality of the plug connections is more important than ever before.

R&M has developed a PoE calculator to help planners, installers and users to evaluate and check their starting conditions.

Help us improve. Send your feedback and suggestions to

Dr. Jan Kupec

By Dr. Jan Kupec

Innovation Project Manager