SynopsisThe paper deals with the main causes of failure, and the necessity for accurate location of cable faults, and describes the methods used to achieve this. The scope is limited to the clearance of faults on power cables and the ancillary cables used in connection with these, including pilot and telephone cables. Serving-fault localisation is also dealt with, since many cables are now fitted with an oversheath of p.v.c, polythene or rubber, and special tests have had to be developed for the location of defects in these. No single method can be used to locate all of the various types of fault which occur, and a systematic approach is necessary. A system comprising analysis, primary test and confirmatory test has therefore been evolved, and the experience of years has confirmed the soundness of this method. Finally, a brief description is given of the pulse-reflection method, using an oscilloscope. Development work on this method, particularly in Europe, has resulted in the production of useful practical instruments.

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Before attempting to locate underground cable faults on direct buried primary cable, it is necessary to know where the cable is located and what route it takes. If the fault is on secondary cable, knowing the exact route is even more critical. Since it is extremely difficult to find a cable fault without knowing where the cable is, it makes sense to master cable locating and tracing and to do a cable trace before beginning the fault locating process. Success in locating or tracing the route of electrical cable and metal pipe depends upon knowledge, skill, and perhaps, most of all, experience. Although locating can be a complex job, it will very likely become even more complex as more and more underground plant is installed. It is just as important to understand how the equipment works as it is to be thoroughly familiar with the exact equipment being used.

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