Type 241 6.6/6.6kV 3x120mm² Pilot Core Resistance Testing: Complete Continuity Verification and Field Acceptance Procedures for Underground Mining Cables
The central pilot core in an AS/NZS 1802 Type 241 6.6/6.6kV 3x120mm² cable should exhibit a measured DC resistance of approximately 0.350 to 1.050 ohms per kilometer at 20°C, depending on the pilot conductor’s specific cross-sectional area (typically 16mm² or 25mm² in this cable class). For a typical 1,000-meter installation cable segment, the measured resistance across the entire pilot conductor pair (measuring between one end and the remote end, or using a calculated pro-rata method for field acceptance) should not exceed 1.050 ohms for a 16mm² pilot, or approximately 0.690 ohms for a 25mm² pilot. These resistance values serve as acceptance criteria for cable deliveries and provide a baseline against which future field testing can detect degradation caused by moisture ingress, oxidation, mechanical damage, or other environmental stress. The pilot core must demonstrate electrical continuity (resistance approaching zero would indicate an open circuit) while remaining within the specified upper bound (excessive resistance would indicate partial failure or contamination). Testing is performed using a standard digital multimeter set to resistance/ohms mode or using a dedicated cable tester with DC ohmmeter functionality, applied across the pilot conductor terminals at each cable end.
