Cutting a station wire disables the one zone it feeds. Cutting the common wire — which every valve shares — disables every zone downstream of the break, which is why a single shovel strike can take out a whole system. The number of affected zones is the most informative symptom available, and it tells a technician which wire to chase before anyone picks up a locator.
How the wiring is arranged
Irrigation valves run on low-voltage alternating current, nominally 24 volts, supplied by a transformer in or at the controller. Each valve needs a complete circuit, and that circuit is made from two wires: a station wire running from its own terminal on the controller out to that valve, and a common wire that returns from every valve back to the controller’s common terminal.
The station wires are individual. The common wire is shared, usually run as a single conductor that is spliced to each valve in turn as it passes along the manifold and out across the property.
That shared conductor is the vulnerability. One break in it opens the return path for every valve beyond the break, and all of them stop working at once even though nothing is wrong with any of them.
Reading the symptom pattern
Notice the difference between a clean cut and crushed insulation. A severed wire is an open circuit and the zone is simply dead. Damaged insulation is a short, which draws current it should not, and that is what trips controllers and blows fuses. The second is more disruptive and, oddly, often easier to find electrically because it announces itself.
| Zones affected | Likely wiring fault |
|---|---|
| One zone only | That zone’s station wire, its splice, or its solenoid |
| Several adjacent zones on the same manifold | Common wire break between manifolds, or a shared splice |
| Every zone, controller otherwise normal | Common wire break near the controller, or the common terminal itself |
| One zone intermittent, worse after rain | Damaged insulation or a failed splice in a wet box |
| Controller shows a fault or trips on one station | Short between station and common — damaged insulation, not a clean cut |
| Fuse blown, nothing runs | Short somewhere in the field drawing excessive current |
Why the damage often surfaces weeks later
Direct-burial irrigation wire is insulated, and a nick that removes some insulation without severing the copper keeps working fine at first. Then moisture reaches the exposed conductor, corrosion sets in or a short develops, and the zone fails — days or weeks after the digging that caused it.
This is why "nothing has been dug recently" so often turns out to mean "nothing in the last three weeks". When you report a new fault, mention any work in the last couple of months: landscaping, fencing, a mailbox post, a tree planted, aeration, a utility trench. It is the single most useful thing you can tell a technician, and it frequently turns a property-wide search into a ten-minute one.
Want this looked at rather than read about?
Diagnostic-first visits across North Georgia. Call 770.335.8595 or request service — you get an estimate before any work begins.
How a break is located and repaired
- Measure at the controller first. Voltage on each station terminal, then resistance across station and common for every zone. This separates controller faults from field faults and identifies open circuits and shorts without any digging.
- Check the valve boxes. Splices fail far more often than wire does. A box holding water with tape or indoor wire nuts inside it is the likeliest fault on any older system, and it is found by lifting a lid rather than by locating.
- Put a signal on the wire. An inductive transmitter at the controller energises the suspect wire and a receiver follows it across the property. Where the signal stops is the break.
- Excavate at the located point. One hole by hand, not a trench along the route.
- Splice properly. Direct-burial gel-filled connectors, sized to the wire. Tape and indoor wire nuts are why so many of these faults are repeat visits.
- Re-test every zone, not just the failed one. A common wire repair should be verified across the whole system, and resistance readings on every station catch the next fault before it surfaces.
Cost and prevention
Irrigation Medics bills $125 for the first hour on site and $80 per hour after, with parts separate. As a general North Georgia market figure, wiring troubleshooting and repair commonly runs roughly $150 to $600 or more depending on how far the fault runs from the controller and what is above it — a market estimate, not a quote. See the cost guide and irrigation electrical repair.
Prevention is mostly documentation. Knowing where valve boxes and wire runs are, flagging them before any crew digs, and telling contractors the system exists prevents most of this. Utility locate services mark public utilities — they do not mark private irrigation, so providing that information is the property owner’s job.
Related answers
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Services that fix this
Irrigation Electrical Repair
Cut wires, shorts, blown fuses and corroded splices — traced to the break instead of guessed at.
Read more →Sprinkler Zone Repair
One zone dead while the rest run fine — the most common irrigation call there is, and the most diagnosable.
Read more →Irrigation Repair
Diagnostic-first repair for residential and commercial sprinkler systems across Hall County, Gwinnett County, North Fult
Read more →Where we work
Irrigation Medics repairs irrigation systems across Hall County and the Lake Lanier communities, the Gwinnett corridor through Duluth, Suwanee and Buford, and North Fulton and Forsyth — Johns Creek, Alpharetta, Milton, Roswell and Cumming. Same rates throughout. See the service area.