A test apparatus for an implantable electrode line and also for an electrode line and an implantable device, including a directional coupler or a circulator for coupling an electrical test symbol into at least one electrical conductor of the electrode line and for decoupling the reflected test signal from the electrical conductor of the electrode line. Such a directional coupler makes it possible to couple a test signal, e.g., a steep voltage pulse, into an electrical conductor of the electrode line and to decouple again the returning reflected voltage pulse (namely, the reflected test signal) from the electrical conductor by means of the directional coupler or circulator.A method for testing an electrical conductor of an implantable electrode line including: 1) coupling a test signal into the electrical conductor; 2) decoupling the test signal reflected in the electrical conductor from the electrical conductor; and 3) evaluating the reflected test signal.