Do connecting cables have to be UL certified?

If an "NEC Class 2 Circuits", an energy-limited circuit with a max. voltage of 30 V AC or 42 V DC, max. current of 5 A and a max. power of 100 VA, is present, then there is no risk of electric shock or fire according to UL definition. Thus, there is no need for UL rating for plugs and cables. For equipment not rated for "NEC Class 2 Circuit," approval is required for the cables.