725 – Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited Circuits

725.48(B)(1) – Class 1 Circuits and Power-Supply Circuits

Change at a Glance:

Revision permits Class 1 circuits to share enclosure space with conductors of electric light, power, non–power-limited fire alarm and medium power network-powered broadband communications circuits as long as separated by a barrier.

725.48 Conductors of Different Circuits in the Same Cable, Cable Tray, Enclosure, or Raceway. (Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited Circuits)

Class 1 circuits shall be permitted to be installed with other circuits as specified in 725.48(A) and (B).

(A) Two or More Class 1 Circuits. (see NEC for complete Code text)

(B) Class 1 Circuits with Power-Supply Circuits. Class 1 circuits shall be permitted to be installed with power-supply conductors as specified in 725.48(B)(1) through (B)(4).
(1) In a Cable, Enclosure, or Raceway. Class 1 circuits and power-supply circuits shall be permitted to occupy the same cable, enclosure, or raceway without a barrier only where the equipment powered is functionally associated.
Class 1 circuits shall be permitted to be installed together with the conductors of electric light, power, non-power-limited fire alarm, and medium power network-powered broadband communications circuits where separated by a barrier.

725.144 and Table 725.144 – Transmission of Power and Data

Change at a Glance:

Extensive revision occurred for 725.144, Table 725.144, 725.144(A), and 725.144(B) dealing with transmission of power and data on Class 2, Class 3, Class 2-LP, or Class 3-LP cables.

725.144 Transmission of Power and Data (Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited Circuits)

725.144 Transmission of Power and Data. The requirements of Sections 725.144(A) and (B) shall apply to Class 2 and Class 3 circuits that transmit power and data to a powered device. The requirements of Parts I and III of Article 725 and Section 300.11 and Parts I and III of Article 725 shall apply to Class 2 and Class 3 circuits that transmit power and data. The conductors that carry power for the data circuits shall be copper. The current in the power circuit shall not exceed the current limitation of the connectors.

[See NEC for complete text of (6) informational notes following 725.144]

Table 725.144 Ampacities of Each Conductor in Amperes in 4-Pair Class 2 or Class 3 Data Balanced Twisted-Pair Cables Based on Copper Conductors at an Ambient Temperature of 30°C (86°F) with All Conductors in All Cables Carrying Current, 60°C (140°F), 75°C (167°F), and 90°C (194°F) Rated Cables

(See Illustrated table provided and NEC for complete text of Table 725.144 and informational notes)

(A) Use of Class 2 or Class 3 Cables to Transmit Power and Data. Where Types CL3P, CL2P, CL3R, CL2R, CL3, or CL2 transmit power and data, the following shall apply, as applicable: rated current per conductor of the power source shall not exceed (1) the ampacity ratings ampacities in Table 725.144 shall apply to the nominal current at an ambient temperature of 30°C (86°F). (2) For ambient temperatures above 30°C (86°F), the correction factors of 310.15(B)(2) in Table 310.15(B) (1) or Equation 310.15(B) shall apply.
Exception: Compliance with Table 725.144 shall not be required for installations where conductors are 24 AWG or larger and the rated current per conductor of the power source does not exceed 0.3 amperes.
Informational Note: One example of the use of Class 2 cables is a network of closed-circuit TV cameras using 24 AWG, 60°C rated, Type CL2R, Category 5e local area network (LAN) cables balanced twisted-pair cabling.

(B) Use of Class 2-LP or Class 3-LP Cables to Transmit Power and Data. Types CL3PLP, CL2P-LP, CL3R-LP, CL2R-LP, CL3-LP, or CL2-LP shall be permitted to supply power to equipment at from a current level power source with a rated current per conductor up to the marked ampere limit located immediately following the suffix “-LP” and shall be permitted to transmit data to the equipment. Where the number of bundled LP cables is 192 or less and the selected ampacity of the cables in accordance with Table 725.144 exceeds the marked current limit of the cable, the ampacity determined from the table shall be permitted to be used. For ambient temperatures above 30°C (86°F), the correction factors of Table 310.15(B)(1) or Equation 310.15(B) shall apply. The Class 2-LP and Class 3-LP cables shall comply with the following, as applicable:
Informational Note 1: The “(xxA)” following the suffix -LP indicates the ampacity of each conductor in a cable.
Informational Note 2: An example of a limited power (LP) cable is a cable marked Type CL2- LP (0.5A), 23 AWG. A Type CL2- LP (0.5), 23 AWG could be used in any location where a Type CL2 could be used; however, the LP cable would be suitable for carrying up to 0.5 A per conductor, regardless of the number of cables in a bundle. If used in a 7-cable bundle, the same cable could carry up to 1.2 amperes per conductor.
(1) Cables with the suffix “-LP” shall be permitted to be installed in bundles, raceways, cable trays, communications raceways, and cable routing assemblies.
(2) Cables with the suffix “-LP” and a marked ampere level current limit shall follow the substitution hierarchy of Table 725.154 and Figure 725.154(A) for the cable type without the suffix “-LP” and without the marked ampere level current limit.
(3) System design shall be permitted by qualified persons under engineering supervision.
Informational Note: An example of a limited power (LP) cable is a cable marked Type CL2-LP (0.5A), 23 AWG.