An electric motor with a casing in which a stator in coaxial arrangement with the motor shaft and a rotor are disposed, and a terminal box which is attached to a casing peripheral wall and in which electronic components are arranged. Between the terminal box and the casing a breakthrough is provided on the one hand and an auxiliary impeller firmly connected to the motor shaft is mounted inside the motor casing on the other hand such that an air stream can flow from the interior of the casing into the interior of the terminal box and/or vice versa when the electric motor is operating.
