Electrical lines can short or break due to stress, such as a sudden jolt in excess electricity, or become compromised by a nick or cut. Because electrical lines are concealed behind walls or buried in the ground, finding an electrical line break might seem too big a job. But there are methods for locating an electrical line break even if the wire is not completely accessible or exposed.
Do a visual inspection first. Look for discoloring on the wall about 4 feet from the floor. Most residential wiring is laterally run inside the structure from room to room. If the wiring is partially exposed, look for nicks or cuts.
Try a binary sort. This method is using the "half-way" point of an electrical line. Uncover the half-way point of the electrical line. Inside, this means cutting a small access way into the wall. If the electrical line is buried, dig at the half-way point. Use a voltage proximity detector or attach a voltage tester to the wire and test for voltage. If no voltage is read, the break is between the source and the half-way mark. Repeat testing by moving a few feet closer to the source until voltage is found.
Use an underground wire tracker fault/break locator. These devices read through earth to find line breaks and faults and are also known as RF-null wire trackers. Run the underground wire tracker above the path of the electrical line to find the break.