These requirements cover toy transformers designed to be used on nominal 120-V branch circuits. A toy transformer is a step-down isolating transformer of the low-secondary-voltage type. It is intended primarily to supply current to electrically operated toys, and as such is expected to be subjected to careless use and probable short circuit of the secondary terminals. Accordingly, the design of a toy transformer takes into consideration the rather unusual risk of fire that may be involved, and the construction is made to reduce the risk of fire with respect to the ignition of nearby combustible material as the result of overheating or eventual inoperative condition of the transformer itself. These requirements do not cover toys or the like designed to operate from the secondary output of a toy transformer. Toy transformers marked "Class 2" are evaluated to the requirements in the Standard for Class 2 Power Units, UL 1310, and to the requirements in this Standard.