Underground Residential Distribution Cable Fault Locating SOP

Step-by-step procedure for locating, isolating, and documenting faults on underground residential distribution (URD) cable, including test equipment setup, switching coordination, and outage control.

Steps

• Confirm the outage scope and fault report
  The switching coordinator verifies the outage ticket, affected feeder, customer reports, and any prior fault history. The coordinator records the suspected circuit, last known normal status, and whether the fault is permanent or intermittent. If the scope is unclear, the coordinator escalates to the supervisor before field deployment.
• Review the switching order and obtain authorization
  The switching coordinator reviews the approved switching order with the field crew and confirms each actor's role. The coordinator verifies that all required approvals, clearances, and notifications are in place. If the switching order is missing, inconsistent, or not understood, the coordinator stops the job and escalates.
• Establish the work zone and apply PPE controls
  The field technician sets barricades, warning signs, and access controls around the test area. The technician verifies that all crew members are wearing the required PPE and that the work zone is clear of bystanders. If the site cannot be controlled, the technician pauses work and escalates.
• Isolate the faulted section
  The field technician performs the approved switching steps to isolate the suspected fault section. The technician applies lockout/tagout and grounds or bonds the circuit as required by the switching order and utility practice. The technician verifies de-energization using approved methods before any cable testing begins.
• Verify isolation and absence of voltage
  The competent person verifies the test instrument on a proving source, tests the isolated conductors, and then re-proves the instrument. The competent person records the result and confirms the section is safe for fault location testing. If any voltage is detected, the crew stops and escalates immediately.
• Set up the fault locating equipment
  The field technician connects the selected fault locating equipment according to the manufacturer's instructions and the utility test plan. The technician verifies cable identification, test lead integrity, and instrument settings before energizing the test set. If the setup does not match the cable type or fault mode, the technician stops and requests technical review.
• Perform the initial fault test and record readings
  The field technician runs the approved initial test method and records the measured values, instrument settings, and observed fault signature. The technician repeats the reading if the result is outside the expected tolerance or appears inconsistent. If readings vary beyond the allowed deviation, the technician flags a non-conformance and escalates for a second review.
• Locate the fault segment using the earth gradient method or approved alternative
  The field technician follows the approved earth gradient technique or other authorized locating method to narrow the fault location along the cable route. The technician marks the suspected fault point and compares the result against the route map and prior readings. If the location cannot be narrowed within the required tolerance, the technician repeats the test or escalates to a senior troubleshooter.
• Coordinate excavation or access only after location confirmation
  The switching coordinator reviews the location evidence and decides whether the fault point is confirmed. If the result is within tolerance, the coordinator authorizes controlled access or excavation coordination. If not, the coordinator returns the crew to additional locating steps and documents the deviation.
• Document the fault, isolation actions, and escalation status
  The field technician records the final fault location, test method used, isolation steps, equipment settings, and any deviations from the approved procedure. The technician attaches photos or sketches of the marked location and notes any escalation to supervision or engineering. If the fault could not be isolated or located, the technician documents the non-conformance and the next action owner.
• Obtain approval before restoration or repair handoff
  The supervisor or switching authority reviews the completed documentation, confirms the fault location status, and authorizes the next step in the restoration or repair workflow. If the documentation is incomplete or the circuit condition is uncertain, the reviewer withholds approval and requests corrective action.