Electric conductivity of composite materials was determined using a high-voltage meter Agilent 4339B. It can provide direct current voltages up to 1 kV and detects currents from 60 fA to 500 µA. Prior to mechanical testing the cut bending bar samples, the flanks of the manufactured rectangular specimens were covered with silver conductive paint and connected with clamps. The measurement setup was placed in a shielded resistivity cell (Agilent 16008B).