How to Locate Wire and Cable Breakpoints Using a Digital Multimeter
Apart from measuring basic parameters such as voltage, current, resistance, capacitance and transistors, a digital multimeter can also be used creatively to expand its capabilities for multi‑purpose applications. Described below is the method for identifying breakpoints in wires and cables with a digital multimeter.
When an internal break occurs within a cable, the exact location of the fracture is difficult to pinpoint due to the outer insulating sheath. A digital multimeter can resolve this problem easily. The detailed procedure is as follows: Connect one end of the broken wire (cable) to the 220 V AC live conductor, and leave the opposite end open‑circuited. Set the digital multimeter to the AC 2 V range. Starting from the live‑wire connection end of the wire (cable), grip the tip of the black probe with one hand, and slide the red probe slowly along the cable's outer insulation. The displayed voltage reading will be around 0.445 V (measured on a DT890D multimeter). When the red probe reaches a certain point, the reading drops abruptly to a few hundredths of a volt (approximately one‑tenth of the original value). The cable breakpoint lies roughly 15 cm toward the live‑wire connection side from this position.
This technique will not work for shielded cables if only the inner core conductor is broken while the shield layer remains intact.
