What is the method of measuring resistivity of semiconducting screen for cable ?

E-1 Each test piece shall be prepared from a 150 mm sample of complete cable. The conductor screen test piece shall be prepared by cutting a sample of core in half  ongitudinally and removing the conductor and separator, if any. The insulation screen test piece shall be prepared by removing all the covering from the sample of the core.
The procedure for determining the volume resistivity of screen shall be as follows:
Four silver plated electrodes A, B, C and D (see Fig. 1) shall be applied to the semi-conducting surfaces. The potential electrodes B and C shall be 50 mm apart and
the two current electrodes A and D shall be each placed at least 25 mm beyond the potential electrodes. Connection shall be made to the electrodes by means of suitable clips. In making connections to the conductor screen electrodes, it shall be ensured that
the clips are insulated from the insulation screen on the outer surface of the test sample.
The assembly shall be placed in an above preheated to the specified temperature and, after an interval of at least 30 min, the resistance between the electrodes shall be  measured by means of circuit, the power of which shall not exceed 100 mW. After the electrical measurements, the diameters over the conductor screen and insulation screen and the thicknesses of the conductor screen and insulation