The portable Wheatstone bridge is often used to locate faults in multicore cables,telephone wires, or power transmission lines by means of Murray-loop. This test is used in particular to find the location of short circuits or low-resistance faults between a conductor and ground.
A commercial Wheatstone bridge, entirely self-contained with batteries and a pointer-type galvanometer, and with the special connections required for these loop tests, is known as a test set. The best known and simplest of the various loop tests is called Murray-loop test, principally used to locate ground faults in sheathed cables. The test setup is shown in Fig. in the PPT