a heat - generating element of a heating device for heating air includes at least one ptc element and , lying on opposing side surfaces of the ptc element , electric strip conductors . a heat - generating element that is improved with respect to the safety against electric flashovers is created with the invention under consideration by means of surrounding the two electric strip conductors on the outside by a non - conductive insulating layer . a heating device for heating air with multiple heat - generating elements is also disclosed with each heating element including at least one ptc element and , lying on opposing side surfaces of the ptc element , electric strip conductors and multiple heat - emitting elements that are arranged in parallel layers and that are held in position lying on opposing sides of the heat - generating element . the heat - emitting elements are essentially potential - free and protected against electric flashovers with a higher degree of certainty due to the fact that the heat - emitting elements lie on opposing sides of the heat - generating element , with an insulating layer placed in between .