Abstract: The device includes an elongated electrical heating unit (20) whose length matches the length of an elongated opening in the device, and has a switching system to activate an electrical circuit at the moment when sheets to be bound are placed on the heating unit (20). Heating unit (20) is wired in series with a switch (11) in the switching system and a heating current switch (31). Means are provided to keep this heating current switch (31) turned on when the switching system is turned on. The device includes a comparator (34) whose input is connected to a temperature sensor (26); when a predetermined upper temperature limit (T.sub.max) is reached it turns off the heating current switch (31). There is also a provision so that after the heating current switch (31) is turned off it is kept off until the switch (11) in the switching system has been switched off and then on again.