For listing purposes, Tables 11(A) and 11(B) provide the required power source limitations for Class 2 and Class 3 power sources. Table 11(A) applies for alternating-current sources, and Table 11(B) applies for direct-current sources.
The power for Class 2 and Class 3 circuits shall be either (1) inherently limited requiring no overcurrent protection, or (2) not inherently limited requiring a combination of power source and overcurrent protection. Power sources designed for interconnnection shall be listed for the purpose.
As part of the listing, the Class 2 or Class 3 power source shall be durably marked where plainly visible to indicate the class of supply and its electrical rating. A Class 2 power source not suitable for wet location use shall be so marked. Exception: limited power circuits used by listed information technology equipment.
Overcurrent devices, where required, shall be located at the point where the conductor to be protected receives its supply and shall not be interchangeable with devices of higher ratings. The overcurrent device shall be permitted as an integral part of the power source.
Article 90 Introduction
Wiring and Protection
Wiring Methods and Materials
Equipment for General Use
Annex C. Conduit and Tubing Fill Tables for Conductors and Fixture Wires of the Same Size
Annex D. Examples
Annex E. Types of Construction