When your landscape lights stop working, the cause is usually simple: a tripped outlet, a timer that lost its settings after a power outage, or a cable cut by a shovel. This guide walks through the checks a homeowner can safely make, organized by what you’re seeing, and explains when it’s time to call a lighting technician.
North Star Outdoor Lighting repairs and maintains low-voltage landscape lighting systems across Scottsdale and the greater Phoenix area. If you’d rather skip the troubleshooting, call us at (480) 248-0194.
The Most Common Reasons Landscape Lights Stop Working
In our experience, most “my lights are out” calls come down to one of these:
- A tripped GFCI outlet or breaker. Monsoon storms and irrigation overspray are frequent triggers in Arizona.
- A timer or photocell problem. Timers lose their settings after power outages, and photocells get blocked by plants or dirt.
- A damaged cable. Shovels, aerators, trenching, and pack rats are the usual culprits.
- Failed bulbs or LED fixtures. Heat shortens the life of drivers and lamps, especially in fixtures that sit in full sun.
- An overloaded or failing transformer. This is common after someone swaps in higher-wattage bulbs.
Before You Start: Stay Safe
Most residential landscape lighting is low voltage. A transformer plugged into a standard outdoor outlet steps household power (120 volts) down to about 12 to 15 volts, and that low-voltage power runs through the buried cable to each fixture.
- The cable and fixtures on the low-voltage side are generally safe to handle. Still, unplug the transformer before you open fixtures or splices.
- The outlet, the breaker panel, and anything inside the transformer’s 120-volt side are line voltage. If you’re not comfortable working with household electrical, leave those to a professional.
- Call Arizona 811 before you dig more than a few inches to look for a buried cable, so you don’t hit gas, water, or power lines.
Quick Checks to Try First
These five checks take about ten minutes and solve a large share of problems.
- Find the transformer. It’s a metal or plastic box, usually mounted on a wall or post near an outdoor outlet, often by the garage, the side yard, or the pool equipment.
- Check the outlet. If the transformer is plugged into a GFCI outlet, press the Reset button. GFCI outlets are often wired in a chain, so the one that tripped might be in the garage, a bathroom, or on the patio. Check those too. Then check your breaker panel for a tripped breaker.
- Check the transformer’s own switch and breaker. Many transformers have an on/off/auto switch and a small reset button or breaker on the side or inside the door.
- Check the timer. If it has a clock, make sure it shows the right time and that the on and off times are set. A power outage can reset older mechanical and digital timers.
- Check the photocell. If the lights come on at dusk automatically, find the small light sensor (on the transformer or on a short cable) and make sure it isn’t covered by plants, dirt, or a shadow. Covering it with your hand should switch the lights on within a minute or two when the switch is set to automatic.
Troubleshooting by Symptom
None of the lights come on
Start with the quick checks above. If the outlet has power and the transformer’s switch is on but nothing lights, the transformer may have tripped its internal breaker because it’s overloaded or there’s a short somewhere on the system. Unplug it for a few minutes, plug it back in, and see whether the lights come on and stay on.
If the transformer hums but nothing lights, or it’s dead even with power at the outlet, it may have failed. Transformers do wear out, especially older units mounted in direct afternoon sun. That’s a job for a technician.
The lights come on at the wrong times
If the lights come on too early, too late, or not at all at night, the timer or photocell is the likely cause:
- On too early or in the daytime: the photocell is in a shaded spot or covered, or it’s failing. A photocell needs a clear view of daylight.
- Not on at night: the timer’s off-time may be set before its on-time, or a power outage reset the clock.
- On all the time: the switch may be set to “on” instead of “auto,” or the photocell or timer has failed.
Arizona doesn’t observe daylight saving time, so a timer that jumps an hour twice a year may be set to the wrong time zone or region. Most smart and astronomic timers have a setting for this.
The lights turn on and off by themselves at night
Lights that cycle on and off are usually a sign the transformer is protecting itself. Two common causes:
- Overload. The total wattage of the bulbs is more than the transformer is rated for, so its breaker trips, cools, resets, and trips again.
- A short. A damaged cable, a crushed fixture, or a corroded splice is letting current leak, which also trips the breaker.
Add up the wattage of every bulb on the system and compare it with the rating on the transformer’s label. If you’re over, or close to it, that’s the likely problem. If you’re well under, a technician can locate the short.
One section of lights is out
Most systems have several cable runs coming from the transformer, each serving a group of lights. If one group is dark and the rest work, the problem is almost always on that cable run:
- A cable cut by a shovel, aerator, edger, or new planting
- A loose or corroded connection at the transformer terminal for that run
- A failed splice where the cable connects to the first fixture or branches off
- Chewed wire. Pack rats and other rodents chew landscape lighting cable in Arizona yards.
Think about any recent yard work near that section; it often points straight to the problem. Finding a break in buried cable usually takes a meter and some careful digging, and it’s one of the most common repairs we make.
A single light is out
One dark fixture usually means a failed bulb, a corroded socket, or a loose connection where the fixture’s lead wire is spliced to the main cable.
- Halogen fixtures: replace the bulb with the same wattage and type. Hold new halogen bulbs with a cloth or gloves, because oil from your skin shortens their life.
- Integrated LED fixtures: many modern fixtures have the LED and driver built in, with no bulb to change. When one fails, the fixture or its LED module is replaced.
- Light flickers when you touch or move the fixture: the socket contacts or the connection are loose or corroded.
The lights stopped working after the bulbs were replaced
This is one of the most common calls we get. It usually happens when the new bulbs draw more power than the old ones.
For example: a system has a 600-watt transformer and 25 fixtures with 20-watt bulbs, for a total of 500 watts. Someone replaces ten of the bulbs with 50-watt versions to make the yard brighter. The total jumps to 800 watts, well over the transformer’s rating, and its breaker shuts the system down.
The fix is to put back bulbs of the original wattage, or to have the system redesigned for more light. If you want a brighter yard, switching to LED is usually the better route: LED bulbs produce similar light at a fraction of the wattage, which takes load off the transformer.
The lights are dim or yellow
Dim, yellowish light means the fixtures aren’t getting enough voltage. Common causes:
- Corroded splices. Connections that weren’t fully waterproofed corrode underground, adding resistance and dimming every light past that point. Black electrical tape is a frequent offender.
- Too many lights on one run, or a cable run that’s too long for its wire gauge, so the last fixtures get noticeably less voltage than the first.
- An overloaded transformer that can’t hold its output voltage.
If the whole system has slowly gotten dimmer over the years, corroded connections are the usual cause. A technician can measure voltage at the fixtures and rebuild the bad splices with waterproof connectors.
Bulbs keep burning out
Halogen bulbs are very sensitive to voltage. Running them even slightly above 12 volts shortens their life sharply, and running them slightly below 12 volts makes them last much longer. If the fixture closest to the transformer burns out more often than the others, it’s probably getting too much voltage.
A technician can rebalance the system by moving cable runs to a lower voltage tap on the transformer or rewiring the layout so voltage is more even. Converting to LED solves most burnout problems, since landscape LEDs typically last tens of thousands of hours and tolerate a wider voltage range.
LED lights flicker or buzz
LED flicker usually comes from compatibility: some LED bulbs don’t work well with older magnetic transformers or with certain timers and dimmers. It can also mean voltage at the fixture is outside the bulb’s rated range, or a driver is failing from heat. Replacing bulbs with LEDs rated for your transformer, or upgrading the transformer, usually fixes it.
The GFCI keeps tripping
A GFCI that trips during or after rain or irrigation is reacting to moisture. Look for an outlet cover that doesn’t seal when the plug is in, water pooling around the transformer, or a damaged fixture or splice letting water in. GFCI outlets also wear out with age and start tripping for no reason. If resetting doesn’t hold, have an electrician or lighting technician test the outlet and the system.
Fixtures have white crust or foggy lenses
That’s mineral buildup from Arizona’s hard water. When sprinklers hit hot fixtures, the water evaporates and leaves calcium behind, which clouds lenses and dims the light. Adjust sprinkler heads to keep water off the fixtures, schedule irrigation for when the lights are off, and clean lenses with a lime and calcium remover.
Symptom Quick Reference
| What you see | Likely cause | DIY or call a pro? |
| No lights at all | Tripped GFCI or breaker, timer, transformer | Try the quick checks; call if the transformer is dead |
| Wrong on/off times | Timer settings, blocked or failed photocell | Usually DIY |
| Lights cycle on and off | Overload or short | Check wattage; call to find a short |
| One section out | Cut cable, bad connection, chewed wire | Call a pro |
| One light out | Bulb, socket, or splice | Bulb is DIY; socket or LED module, call |
| Out after a bulb change | New bulbs overloaded the transformer | DIY: go back to the original wattage |
| Dim or yellow light | Corroded splices, long runs, overload | Call a pro |
| Bulbs burn out fast | Voltage too high (halogen) | Call a pro, or convert to LED |
| LEDs flicker | Incompatible transformer or timer, failing driver | Call a pro |
| GFCI keeps tripping | Moisture or worn-out GFCI | Call a pro |
Maintenance That Prevents Most Problems
A landscape lighting system is out in the heat, dust, and water every day. A check once or twice a year, ideally before summer and before the holidays, catches most problems before they leave you in the dark.
Fixtures
- Clean lenses and clear out dirt, leaves, and insects.
- Re-aim and reposition fixtures as plants grow. A light aimed at a young tree can end up buried in its canopy a few years later.
- Straighten leaning path lights and replace broken stakes.
- Remove mineral buildup and adjust sprinklers that hit fixtures.
Transformer and controls
- Clear debris and insects out of the transformer cabinet.
- Have the terminal connections tightened. They can loosen over time.
- Confirm the timer and photocell settings, especially after outages.
- Test the GFCI outlet and make sure its weatherproof cover closes.
Cable and connections
- Look for exposed or nicked cable, especially along beds and edges where landscapers work.
- Check cable attached to trees and loosen or replace ties so they don’t girdle the trunk.
- Replace any taped or non-waterproof splices with waterproof connectors.
Bulbs
- On halogen systems, replace burned-out bulbs promptly. When bulbs fail, voltage to the remaining bulbs rises and they burn out faster.
- Keep a note of the wattage and type of each bulb, so replacements match.
North Star offers monthly lighting maintenance for homeowners, HOAs, and commercial properties, so the checklist gets done without you having to remember it.
Repair or Upgrade?
If your system is mostly halogen, more than 10 to 15 years old, and needs repairs every season, upgrading may cost less over time than continuing to fix it. Converting to LED cuts energy use, reduces the load on the transformer, and ends the cycle of burned-out bulbs. Our guide on when to repair vs. replace your outdoor lighting system covers the decision in more detail, and our LED conversion service can often reuse your existing cable and fixture locations. Heat is a major factor in Arizona too; see how Arizona heat and sun affect outdoor lighting fixtures.
Get Your Landscape Lights Fixed
If the quick checks didn’t solve it, North Star can find and fix the problem. Our technicians carry the meters and parts to diagnose transformers, locate cable breaks and shorts, rebuild corroded connections, and replace failed fixtures. We also offer 24-hour service and repair.
Call (480) 248-0194 or request service online. We serve Scottsdale, Phoenix, Paradise Valley, and the surrounding Valley communities.
Frequently Asked Questions
Why did all my landscape lights stop working at once?
When every light goes out at the same time, the problem is almost always at the power source: a tripped GFCI outlet or breaker, a timer that lost its settings after a power outage, or a transformer that tripped or failed. Check the outlet, the breaker panel, and the transformer’s switch and timer first.
How do I reset my landscape lighting transformer?
Press Reset on the GFCI outlet the transformer is plugged into, then check the transformer for its own reset button or breaker, usually on the side or inside the cover. Unplugging the transformer for a few minutes and plugging it back in will also reset most units. If it trips again right away, there’s likely an overload or a short that needs a technician.
Why do my outdoor lights turn on and off by themselves?
Lights that cycle on and off at night usually mean the transformer is overloaded or there’s a short somewhere on the system, so its breaker keeps tripping and resetting. Lights coming on at the wrong time of day point instead to a blocked or failing photocell or an incorrectly set timer.
Why is only one section of my landscape lights out?
A dark section usually means a problem on that one cable run: a cable cut during yard work, a loose connection at the transformer, a failed splice, or wire chewed by rodents. These breaks are often underground and take a meter to locate.
Can I replace my halogen landscape bulbs with LED bulbs?
Usually, yes. LED replacement bulbs are made for most common low-voltage fixtures and use far less power, which also takes load off the transformer. Some LED bulbs flicker on older transformers or timers, so choose bulbs rated for low-voltage landscape use, or have the system evaluated for an LED conversion.
How often should landscape lighting be maintained?
Once or twice a year is a good schedule for most Arizona homes: clean lenses, re-aim fixtures as plants grow, check the transformer and timer, test the GFCI, and look for exposed or damaged cable. Regular maintenance prevents most outages and extends the life of the system.
