Q. The Inspector says my DC power supply needs a Class 2 label. What’s he talking about?
The Inspector is referring to the requirements of Class 2 circuits and wiring as defined in the National Electric Code (NEC). The definition of Class 2 circuits specifies the wiring system between the load side of a Class 2 power source and the connected equipment. The definition includes current and voltage limitations [NEC Table 11(A) and Table 11(B)] to limit the possibility of fire initiation and electric shock. Class 2 circuits offer reduced requirements for wire size, wire insulation, over-current protection, wiring methods and installation materials and can be advantageous in reducing cost and improving flexibility of an installation. Also, many local municipalities now require that the NEC Class 2 standard be maintained in public buildings, schools and hospitals.
To be approved by the local Authority Having Jurisdiction (AHJ), one requirement for a Class 2 circuit is that the power source for that circuit must meet the definition of a Class 2 power source as specified in the NEC. In accordance to NEC 2017, a Class 2 power source for DC powered circuits must be a listed Class 2 power supply [NEC Article 725.121(A)]. A listed Class 2 DC power supply is tested and certified by a third-party testing organizations like Underwriters Laboratories to meet Class 2 requirements and will have a label designating it as a listed Class 2 power source. Kele offers a selection of listed Class 2 DC power supplies. Look in the Power Supplies section of Kele.com and some models of the PS5R Series that carry the Class 2 listing.