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The 3P design RJ45 cables are POE, POE+ and 4PPOE compatible

compatibilite POE

More and more active equipment and devices are accepting and requiring a Power Over Ethernet (POE) supply. It is important for the user to have the assurance that their cables will be compatible with the electrical power required by the devices.

Depending on the ranges and categories, the PATCHSEE, DESKPATCH and ThinPATCH cables are manufactured with 24, 26 and 28 gauges (American Wire Gauge: AWG) for ThinPATCH thin cables. The higher the figure, the thinner the copper in the pair conductors.

We are mainly focused on cables with a gauge of. AWG 28. He who can do more can do less.

PoE and PoE+:

In September 2005, the IEEE 802.3at working group officially started working on the PoE + pre-standard to take into account the use of 2 pairs of the Cat 5 Ethernet cable to provide a current of 1250 mA and a power of 60 W to powered equipment. This is to expand the market with more devices and therefore more potential customers.

To date, two standards govern the interoperability of equipment:

IEEE 802.3af (PoE): The electrical supply provided by the equipment (switch, injector) is a maximum of 15.4 W. The voltage is 48 V.

IEEE 802.3at (PoE+): If the equipment supplying the power supply and the device both meet this standard, then a power between 24 and 30 W can be used, always for a voltage of 48 V.

Standard IEEE P802.3bt, also called 4PPoE (4-Pair Power over Ethernet), or PoE++ by extending the name PoE+ of standard IEEE 802.3at, introduces two additional levels of maximum power delivered by the switch, type 3 with 55 W (with a maximum current per pair of 600 mA) and type 4 with 90 W (with a maximum current per pair of 960 mA) distributed over the 4 pairs of the Ethernet cable.

Compared with the PoE and PoE + standards that use two pairs out of four, with equal power output, the 4PPoE improves overall energy efficiency because the losses are halved. For a constant current, the power effectively delivered on four pairs is higher than that available on two pairs.

Approved in March 2017, TSB-184-A provides recommendations for twisted-pair cables that support and power direct current, as well as data routed to networked devices in new installations and applications. It also provides recommendations for managing temperature rises in cables and maintaining operation below maximum temperatures.

Table 2- Temparature rise in air for a category of 28 AWG cord cable v. number of cables in bundle for different current levels per pair (TBD)

Number of Cables in bundle Temperature Rise (°C)
600mA per pair 720mA per pair 1000mA per pair
Air Air Air
1 0.86 1.25 2.40
7 2.67 3.84 7.41
19 5.05 7.27 14.03
24 5.91 8.51 16.41
37 7.96 11.47 -
48 9.58 13.80 -
52 10.15 14.62 -
61 11.41 16.43 -
64 11.82 - -
74 13.16 - -
91 15.38 - -

Following TSB-184-A directives, the remote power supply can be provided via cabling without compromising performance or functionality.

TSB-184-A makes specific recommendations, such as:

  • Leave the cables unbundled to allow better heat dissipation, or using small strands of cables,
  • Limit the number of cables per strand to 24 in order to reduce a potential temperature rise caused by installation factors, a high room temperature, 26 and 28 AWG cables and higher currents,
  • Use of category 6A wiring (Permanent Link) or above for new installations

Finally, TIA/EIA, AWG 28 patch cords, which are popular in high-density patch areas because of their smaller diameter that helps reduce congestion, improve airflow and reduce the curvature radius, are also now recognised in a normative annex to TIA/EIA-568.2-D.

The standard introduces the idea of “asymmetric DC resistance” within a pair. This is the difference in resistance (on a direct current) of two wires in a pair that must not exceed a certain value. More practically, the standard recommends that the pairs used for POE have similar electrical resistances.

They have tested it...