How Do You Find a Broken Wire Underground?

A buried circuit to a shed, a detached garage, or landscape lighting suddenly goes dead in a Toronto or GTA yard, and the obvious question is where along a run that might be twenty or fifty metres long the actual break sits. Digging up the entire trench to find out is the last resort, not the first step. This guide covers how a break is actually located before any digging happens.

How do you find a broken wire underground?

Locating a broken buried conductor starts with narrowing the search electrically before any digging: a continuity or resistance test at both ends identifies whether the circuit is fully open, and a time domain reflectometer (TDR) or a buried cable fault locator can pinpoint the approximate distance to the break by sending a signal down the wire and measuring the reflection point. Combined with a physical cable locator tracing the buried route on the surface, this narrows a dig to a specific metre or two rather than an entire trench.

Step 1: confirm it is actually a break, not something else

• Check the breaker feeding the circuit — a tripped breaker with no reset attempt yet is a different problem than a genuine underground break.
• Check any GFCI protecting the circuit, which may have simply tripped rather than the cable being physically broken.
• Test at the source end (the panel or the point the circuit leaves the building) to confirm voltage is present there, ruling out an upstream issue before assuming the fault is in the buried run itself.

Step 2: trace the physical route first

Before any electrical fault-finding, confirm exactly where the buried cable actually runs — a cable locator (an inductive tracer that follows the buried conductor’s signal from the surface) maps the physical path, which matters because underground runs do not always follow a perfectly straight line, and knowing the route is a prerequisite for translating a “distance to fault” reading into an actual dig location.

Step 3: narrow the fault location electrically

• Continuity/resistance test: with the circuit isolated and de-energized, a meter reading between conductors at each end tells you whether the circuit is open (broken) and gives a baseline resistance reading, though not a precise location on its own.
• Time domain reflectometer (TDR): sends a pulse down the conductor and measures how long it takes for the reflection to return from the break point, converting that timing into a distance estimate — the standard professional tool for this exact problem.
• Combining TDR distance with the traced physical route from step 2 gives a specific point along the actual buried path, rather than just a straight-line distance that may not match how the cable actually runs underground.

Common causes of underground breaks

• A shovel, fence post auger, or landscaping project hitting the cable without anyone realizing at the time.
• Freeze-thaw ground movement over multiple Ontario winters stressing the cable at a fixed point, like a transition fitting or a spot where the burial depth was inconsistent.
• Rodent damage where the cable is shallow enough for burrowing animals to reach.
• A degraded splice or connection point along the run, if the original installation had any underground connection that was never properly rated for direct burial — a code violation on its own, separate from the eventual failure.
• Cable that was never actually rated for direct burial in the first place, degrading faster than proper NMWU or equivalent would have. See can you bury indoor electrical wire underground.

Once the location is narrowed

1. Hand-dig carefully at the identified location rather than machine excavation, to avoid causing further damage while exposing the fault.
2. Confirm the actual break or damage once exposed.
3. Repair with a listed direct-burial splice kit rated for underground use — not a standard indoor wire nut, which is not rated for below-grade moisture exposure.
4. Restore proper burial depth and cover per how deep should a trench be for an electrical line, including warning tape if it was not already present.
5. Test the repaired circuit before backfilling completely, confirming the fix actually resolved the issue.

Why guessing and digging is the wrong approach

Digging along an entire buried run hoping to spot the damage is slow, disruptive to landscaping, and genuinely risky — you are digging near a de-energized but potentially still partially intact circuit, and careless excavation can turn one break into two or three. A proper fault-locating process, even though it takes specialized equipment, is faster and far less destructive than trenching the whole yard.

Expert tip from our ESA-licensed electricians

The underground fault calls we get in the GTA almost always start with a homeowner who has already dug one or two exploratory holes hoping to get lucky, before calling us in. That effort is understandable but usually wasted — a TDR reading combined with the traced route typically narrows the actual dig to within a metre, versus a trench dug blind along the whole run. If a buried circuit goes dead and you cannot immediately identify an obvious cause (recent landscaping work, for instance), call before you start digging. It saves both the yard and the time.

Frequently Asked Questions

What is a TDR and do I need to own one?

A time domain reflectometer estimates the distance to a cable fault by timing a signal’s reflection. It is specialized professional equipment, not a typical homeowner tool.

Can I locate a break with just a multimeter?

A multimeter confirms the circuit is open but does not pinpoint the distance to the fault the way a TDR does.

Should I call Ontario One Call before digging to repair a break?

Yes, always locate public utilities before any digging, even a targeted repair excavation.

Can I splice the repair myself?

Underground splices need a listed direct-burial-rated kit and, for most alterations, licensed contractor work under an ESA notification.

What if the whole cable is degraded, not just one break?

Full replacement of the run is often more practical than repeated point repairs on an aging or improperly rated cable.

Related reading from ezsmart.ca

• How to Bury Electrical Wire Safely in the Yard
• How Deep Should a Trench Be for an Electrical Line?
• Can You Bury Indoor Electrical Wire Underground?
• How to Trace a Wire Through a Wall Without Tearing It Open
• How to Wire a Shed for Electricity?

Contact us

Dead buried circuit in a Toronto or GTA yard? Call ezsmart at 416-838-9006 or use our contact page. An ESA-licensed electrician will locate the fault before any digging starts.