Low-voltage landscape lights dim or out

Every question and answer in this guide. Tap “Step by step” to walk through it.

• Which lights are affected?
  • All of them outIs the transformer’s receptacle live, and is its timer or photocell set right?
    • GFCI was trippedGFCI tripped
    • Timer or photocell was the issueTimer or photocell setting
    • Power and settings are fineTest: Measure the transformer outputExpect: About the tap voltage (around 12 V on the 12 V tap), a bit higher with no load.
      • 0 VTransformer protection tripped or transformer failed
      • NormalTest: Check the first dead light and its connectorExpect: Close to the transformer voltage on the main cable, less a volt or two on long runs.
        • Voltage on the cable, not at the fixtureCorroded or loose connector
        • Voltage at the fixture, lamp outBurned-out lamp or fixture
        • No voltage on the cableCut or broken cable
  • Some out, others fineTest: Check the first dead light and its connectorExpect: Close to the transformer voltage on the main cable, less a volt or two on long runs.
    • Voltage on the cable, not at the fixtureCorroded or loose connector
    • Voltage at the fixture, lamp outBurned-out lamp or fixture
    • No voltage on the cableCut or broken cable
  • Dim, worse toward the endTest: Measure voltage at the last fixtureExpect: Within the fixture’s rated range. Halogen lamps are sensitive; many LED fixtures accept a wider range.
    • Below the fixture’s rangeVoltage drop on a long or overloaded run
    • Within rangeMixed lamp types or a failing lamp