The immersion in water of lead-covered cables, with a view to the detection of faults in the lead sheathing, is discussed. Tests of the time taken to show up these defects in power cables at different water pressures are given for various cable samples. The conclusions drawn are that, except possibly in the case of low-voltage cables, no such defects will be discovered during factory routine, and that for high-voltage cables, at least, water immersion should be definitely discontinued.