Touch-safe heater for the use in enclosures with electrical/electronical components. The design of the heater supports the natural convection which results in a high air-current of warm air. The surface temperatures on the accessible side surfaces of the housing are kept down as a result of the heater design. Our complete range of thermostats and hygrostats can directly be connected to the heater NTL 152. This heater is also available in a version with plug-in thermostat requiring no additional wiring. The heaters are designed for permanent operation.