The power source for a Class 2 circuit shall be one of the following:
- A listed Class 2 transformer.
- A listed Class 2 power supply.
- Other listed equipment marked to identify the Class 2 power source.
- Listed information technology (computer) equipment limited power circuits.
- A dry-cell battery provided that the voltage is 30 volts or less and the capacity is equal to or less than that available from series connected No. 6 carbon zinc cells. [725.121(A)]