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Linkz’s PoE Development

Certification

Simultaneously, Linkz has recognised the ongoing work within UL to support the NFPA and the forthcoming 2017 National Electric Code. Linkz is one of the first companies to qualify a range of cable types within the UL – LP system. (See Table 2). Very quickly results were realized through the use of Linkz’s internal test capability which was found to produce good correlation with the test set up in UL (see Fig.2).

Cable TypeAWGFire RatingPoE LP Classification
Category 6 U/UTP23CM0.5A
Category 6 U/UTP23CMR0.5A
Category 6/6A F/UTP23CM0.5A
Category 6/6A F/UTP23CMR0.5A
Category 7 S/FTP23CM0.6A
Category 6/6A F/UTP23CMP0.6A
Table 2
Note to Table 2 :  Non-Plenum cables have a 75°C Maximum Temperature Rating
Plenum cables have a 90°C Maximum Temperature Rating.

The UL LP system provided for the classification of cables within 3 current carrying classes. These are identified as 0.5A, 0.6A and 0.7A. Whilst IEEE 802.3bt determines a maximum current rating per wire of 0.5A (1.0A per pair) UL has chosen to anticipate the industries next developments and consider additional current ratings per wire up to 0.7A.

From the testing completed by Linkz Industries we believe that only Plenum grade cables will ever be classified by UL as 0.7A capable due to restrictions on permitted temperature rise within the cable and the maximum temperature rating of the cable.

In addition, it is important we recognize that differences exist between the test methodologies used by UL and the International Standards Communities in evaluating current carrying capacity of structured cables. Different bundle sizes are recognized that can have an impact upon the final cable rating.

We advise specifiers and installers to be aware of these fundamental differences and the implications that do exist relating to current carrying capacities of smaller bundles of cables.