Outdoor Lights Not Working? A Homeowner's Troubleshooting Guide
Dead porch, flood, or landscape lights usually come down to a tripped GFCI, a photocell or timer, a bad bulb, or moisture in a fixture. Here's how to walk it down before you call anyone.
Written by Steven Rotan
Licensed Journeyman Electrician — Oregon #883LR
⚠️ Before you start
- Outdoor electrical and water don't mix. Turn off the switch or breaker before opening any fixture, and never work on outdoor wiring in the rain.
- Weatherproof covers and gaskets exist for a reason — a fixture full of water is both a failure and a shock hazard. Address moisture, don't just dry it once.
🧰 Tools you'll need
- Non-contact voltage tester
- Screwdriver
Outdoor lighting lives a hard life — sun, rain, freeze, and bugs — so when it quits, there's a familiar short list of causes. Here's how to work through them safely.
1. Check the GFCI (the usual suspect)
Outdoor circuits are almost always GFCI-protected, and a tripped GFCI is the number-one reason outdoor lights and outlets all go dark at once. The GFCI might be outside under a cover, in the garage, or a GFCI breaker in the panel. Reset it. Rain and moisture are the classic triggers — make sure things are dry first.
2. The photocell or timer
Dusk-to-dawn fixtures use a photocell — a small sensor that turns the light on at dark and off at dawn. When it fails, dirties, or gets fooled by another light shining on it, the fixture acts backwards: off all night, or on all day. Photocells are cheap and often replaceable. If your lights run on a timer, check that it hasn't lost its settings after a power blip.
3. The bulb
Simple but common — especially in flood and coach lights that run for hours. Swap the bulb before assuming anything worse. Use bulbs rated for wet or damp locations as the fixture requires.
4. Moisture in the fixture
Cracked lenses and failed gaskets let water in, which corrodes sockets and trips GFCIs. If a fixture is full of water or the socket is corroded, drying it once won't cut it — reseal or replace it. Water in an outdoor fixture is both a failure and a shock hazard.
5. Low-voltage landscape lights
For plug-in landscape systems: one dark fixture is usually a bad bulb or a corroded connector (those pierce-the-cable connectors corrode over time). A whole zone going dark points to the transformer or a cut cable (hello, garden shovel).
Where a pro comes in
Bulbs, GFCI resets, photocells, and timers are all homeowner-friendly. But buried wiring faults, badly corroded fixtures, or a circuit that keeps tripping wet are worth an electrician — chasing an underground fault or wet connection safely is their job.
Bottom line
Start at the GFCI, then the photocell/timer, then the bulb, then moisture. That order solves the large majority of dead-outdoor-light calls without a service visit.
📞 When to call a professional
Bulbs, GFCI resets, photocells, and timers are homeowner territory. Buried wiring faults, corroded fixtures, or a circuit that keeps tripping wet call for an electrician.
Frequently asked questions
My outdoor lights suddenly all went out — where do I start?
Check the GFCI first. Outdoor outlets and often outdoor lighting circuits are GFCI-protected, and a tripped GFCI (frequently one in the garage or on an exterior wall) can kill the whole run. Reset it, then check the breaker. Moisture after rain is the classic trigger.
My dusk-to-dawn light won't turn on (or won't turn off) — why?
That's the photocell — the little sensor that detects daylight. If it's failed, dirty, or fooled by a nearby light shining on it, the fixture behaves backwards: staying off at night or on during the day. Photocells are cheap and often replaceable. For flood lights with motion sensors, check the sensor's mode and sensitivity settings too.
One low-voltage landscape light is out but the rest work — is it the bulb?
Usually yes — a bad bulb or a corroded connector at that fixture. Low-voltage landscape connectors pierce the cable and corrode over time. Replace the bulb first; if that's not it, redo the connector. If a whole zone is dark, suspect the transformer or a cut cable.
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