TIA Related to Using Data Cables to Transmit Power and Data

Tentative Interim Amendment (TIA) Log #1299 to NFPA 70, National Electrical Code, 2017 edition, revises several Sections in Art. 725 [Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited Circuits]. The comment closing date on this TIA is Sept. 14, 2017.

As outlined in portions of the Emergency Nature section of this TIA:

“By omitting a simple exception to 725.144 for systems at low current levels, the existing text creates a circumstance where it has an adverse impact on the installation of conventional, widely deployed power-over-Ethernet equipment running over existing wiring, which the change seeks to remedy. … These products have been supplying nominal current up to 0.3 amperes/conductor without any demonstrated record of loss. … Under the text of 725.144, as written, these systems and wiring may require consideration of the bundling by the user before installation, whereas today they are user-installable on existing data wiring. This change prevents the unjustified disruption of this ~100 million port per year market, yet retains the intended safety concerns for higher current devices.”

“The new labeling requirement for 725.121(C) asks for labeling of a wide and diverse set of power sources without technical justification. … This TIA would provide an exemption to the marking, relieving the burden for power sources of 0.3 amperes or less nominal current. Additionally, the changes to 725.121(C) in the 2017 NEC code cycle overlooked the fact that these labels would need to apply to high-density multi-port power sources, such as Power over Ethernet switches, with many connection points of the same rating in a small front panel space. The proposed change inserts text to specifically permit a single label in the case where multiple connection points have the same voltage and current outputs, making labeling practical, and removing the adverse burden.”

You can view the full text of the TIA in PDF form by clicking on the download button below.

Note: A TIA is tentative because it has not been processed through the entire standards-making procedures. It is interim because it is effective only between editions of the standard. A TIA automatically becomes a public input of the proponent for the next edition of the standard; as such, it then is subject to all of the procedures of the standards-making process. 

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