Repair guide · Wiring

How to find a broken sprinkler wire

Wiring faults are the repair people fear most and should fear least — nothing about them requires digging up a lawn on faith. The wire path can be tested end to end from the controller with a $[XX] multimeter, and the failure points are so predictable that I check two splice boxes before I ever unspool a tracker. Here's the sequence.

Rule out the cheap stuff first

1. The controller: confirm the display is alive, check the fuse, and verify the transformer puts out 24–28 volts AC across the common and any zone terminal while that zone runs. A lightning-thumped transformer mimics a field wiring failure perfectly — North Texas spring storms hand us a batch every year.
2. The solenoid: the coil on the valve fails more often than buried wire does. Disconnect and ohm-test it directly: 20–60 ohms is healthy. Swapping one is a five-minute job — covered in our valve repair guide.
3. The manual test: if the zone runs when you quarter-turn the solenoid by hand but never from the controller, you've confirmed it: valve good, water good, problem electrical.

Build the ohm map

At the controller, remove the zone wires from their terminals and test each one against the common wire with the meter on ohms. Write the numbers down — the pattern is the diagnosis:

Check where wires actually break

Buried irrigation wire almost never snaps in the middle of an undisturbed run. It fails where humans touched it:

Valve-box splices — the number one culprit by a mile. Decades-old connections made with regular wire nuts (or, my favorite find, electrical tape) corrode in the wet box until the circuit opens. Open every box on the path, tug each splice, and remake anything suspect with gel-filled waterproof connectors. This single step closes most “broken wire” calls.

Anywhere there was recent digging — a new fence line, a planted tree, edging work, a utility trench. The repair memory of the yard is the treasure map.

Bed edges and trunk lines — edgers nick shallow wire where it crosses under bed borders; roots slowly guillotine wire pinned against them.

The trace, when you need it

For a true mid-run break with no dig history to follow, a wire tracker (toner and wand) follows the wire's signal along the lawn until the tone dies — and where it dies, you dig one small hole. Trackers rent for $[XX] a day; using one well takes practice, and on multi-wire bundles the signal bleeds between conductors, which is the polite explanation for why this is the point where many homeowners call us. It's also exactly how we find lost valve boxes — tracing the wire leads to the valve every time.

Make the repair permanent

1. Cut back to bright copper on both sides of the break or bad splice.
2. Splice with gel-filled waterproof connectors only — the grease-capsule kind rated for direct burial. Standard wire nuts in soil are a one-season repair.
3. Leave a drip loop of slack wire coiled at the splice so soil movement works the loop, not the connection.
4. Retest the ohm map at the controller before you backfill. Confirm the number, then bury it.

When to have a licensed irrigator do it

Call when the ohm map says “open” but every splice checks good, when multiple zones are dead and the common is the suspect, when a surge took out the controller and field wiring together, or when you'd like the lost valve boxes found and raised while we're in there. Diagnosis with instruments, a flat rate before any work begins: sprinkler wiring & controller repair.