518.4(B) Communications, Signaling Systems, Data Systems, Fire Alarm Systems, and Systems Less Than 120 Volts, Nominal.
Code Change Summary: A new section was added to address limited energy circuits and wiring systems often installed in assembly occupancies.
For years, Section 518.4(A) has provided positive language on wiring methods permitted to be used in assembly occupancies and an exception pointed the code reader to additional articles for other circuit types and systems installed in assembly occupancies.
In the 2023 NEC®, new Section 518.4(B) was created by reworking the exception previously in 518.4(A) into positive language and modifying it to include Class 2 circuits that transmit power, data, or both to a powered device.
In the 2023 NEC®, new Section 518.4(B) covers communications, signaling systems, data systems, fire alarm systems, and systems less than 120 volts, and requires the fixed wiring methods for these circuits and systems to be as follows:
(1) Audio signal processing, amplification, and reproduction equipment – refer to 640.9
(2) Communications systems — Refer to Part IV of Article 805 and Part VI of Article 840
(3) Class 2 and Class 3 remote control and signaling circuits – refer to Article 725, Part III
(4) Class 2 circuits that transmit power, data, or both to a powered device
Power Over Ethernet (POE) uses data cables such as Cat 5 or Cat 6 to power LED lighting or other low energy consuming equipment that can operate at limited voltage levels.
Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2023 NEC® edition of NFPA 70.
2020 Code Language:
518.4(A) General. The fixed wiring methods shall be metal raceways, flexible metal raceways, nonmetallic raceways encased in not less than 2 inches of concrete, Type MI, MC, or AC cable. The wiring method shall itself qualify as an equipment grounding conductor according to 250.118 or shall contain an equipment grounding conductor sized in accordance with Table 250.122.
Exception: Fixed wiring methods shall be as provided in the following:
(1) Audio signal processing, amplification, and reproduction equipment — Article 640
(2) Communications systems — Chapter 8
(3) Class 2 and Class 3 remote-control and signaling circuits — Article 725
(4) Fire alarm circuits — Article 760
2023 Code Language:
518.4(A) General. The wiring method shall qualify as an equipment grounding conductor in accordance with 250.118 or shall contain an equipment grounding conductor sized in accordance with Table 250.122, and shall be any of the following:
(1) Metal raceways
(2) Flexible metal raceways
(3) Nonmetallic raceways encased in not less than 50 mm (2 in.) of concrete
(4) Type MI, Type MC, or Type AC cable
N 518.4(B) Communications, Signaling Systems, Data Systems, Fire Alarm Systems, and Systems Less Than 120 Volts, Nominal. Fixed wiring methods for specific installations shall be as follows:
(1) Audio signal processing, amplification, and reproduction equipment — 640.9
(2) Communications systems — Part IV of Article 805 and Part VI of Article 840
(3) Class 2 and Class 3 remote control and signaling circuits — Article 725, Part III
(4) Class 2 circuits that transmit power, data, or both to a powered device