NEC 2023 690.31(D) Direct-Current Circuits on or in Buildings
Article 690.31(D)(2) (Marking and Labeling) requires PV DC wiring enclosures must be permanently labeled with “PHOTOVOLTAIC POWER SOURCE” or “SOLAR PV DC CIRCUIT” unless their set up and purpose is immediately obvious.
Helps maintenance personnel and emergency responders recognize PV circuits instantly, avoiding confusion and hazards, and ensures compliance with inspection and safety requirements throughout the life of the system.
