When an underground power cable fails, every hour of searching is an hour of downtime. Underground cable fault location is the discipline of finding the exact position of a cable fault – quickly, safely and without damaging the healthy cable – so the repair crew digs once, in the right place. Tecnvolt performs cable fault location with dedicated equipment (BAUR Syscompact class systems) combining time-domain reflectometry, impulse current methods and acoustic pinpointing.
The fault location workflow
Professional fault location follows a proven sequence that minimizes both time and stress on the cable:
1. Diagnosis of the fault type. Insulation resistance and breakdown behavior identify whether the fault is low resistance (bolted), high resistance, intermittent or a sheath fault. The fault type determines the method.
2. Prelocation. Time-domain reflectometry (TDR) sends fast pulses down the cable and reads reflections; for high resistance faults, methods such as impulse current (ICM) or secondary impulse (SIM/MIM) convert the fault into a momentary arc that TDR can see. Prelocation narrows the fault position to within a few percent of the route length in minutes.
3. Pinpointing. A surge generator (thumper) applies controlled impulses while an acoustic and electromagnetic ground sensor pinpoints the discharge – typically within centimeters – marking the exact excavation spot.
4. Verification and documentation. After repair, the circuit is retested – ideally with VLF withstand – before re-energization, and the event is documented for the asset history.
Why controlled fault location matters
Random thumping at full energy to “listen for the bang” is a legacy practice that overstresses healthy cable sections and accelerates future failures. Modern fault location uses the minimum energy necessary: precise prelocation first, short pinpointing second. The result is less collateral damage, faster restoration and lower lifetime cost for the cable asset.
Sheath fault location
Damage to the outer jacket admits moisture that slowly destroys MV cables from the outside in. Sheath testing applies DC between metallic screen and earth to detect jacket faults, and step-voltage methods locate them precisely – a critical service after directional drilling, civil works near routes, or before accepting a new installation.
Applications
Emergency response to in-service failures on industrial feeders, distribution circuits, port and airport networks and commercial campuses; acceptance verification of new installations, including jacket integrity; and route audits where repeated third-party excavation damage is suspected.
What you receive
A fault location report documenting fault type, prelocation traces, pinpointed position with route references, applied energies, and repair verification results – plus recommendations to prevent recurrence, such as circuit-wide diagnostics when the failure pattern suggests systemic aging.
Why Tecnvolt
Tecnvolt has located faults on industrial and utility networks across Brazil since 2012, integrating fault location with full cable diagnostics so that a repaired circuit returns to service proven, not presumed, healthy. ISO 9001, ISO 14001 and ISO 45001 certified.
Frequently asked questions
How long does it take to find a fault? With proper prelocation, most faults are pinpointed within hours of arrival on site – the excavation usually takes longer than the location.
Does thumping damage the cable? Applied correctly – minimum energy after accurate prelocation – the stress is brief and localized. Uncontrolled full-energy thumping without prelocation is what damages circuits.
Can you locate faults on jacketed cables in duct banks? Yes – TDR and acoustic/electromagnetic pinpointing work in ducts, direct-buried routes and mixed constructions.
About our U.S. transition
Tecnvolt Engenharia is a Brazilian company founded in 2012, currently in the process of establishing a U.S. company in Houston, Texas. During this transition we are receiving inquiries and scheduling future work. Request a quote / register interest