If you've ever walked out at night and noticed one of your landscape lights glowing dimly behind a fogged lens, you've seen the most common failure mode in outdoor lighting. It isn't usually a bad bulb or a wiring fault. It's water, and in Maryland it's the thing that ends most fixtures' lives.
TLC has been lighting Maryland homes for decades, which means we build for Maryland conditions: solid brass and copper fixtures, waterproof direct-burial connections, and wiring routed so water drains instead of collecting. It's the difference between a system that lasts fifteen years and one that starts failing in its fourth spring.
Here's why water gets in to your outdoor lighting fixtures, where the water gets in, and what actually keeps the water out.
Why Maryland is Hard on Outdoor Lighting Fixtures
Humidity here isn't a summer inconvenience. It's a year-round load on anything sealed.
Summer dew points sit in the high 60s and low 70s for weeks at a stretch. Annual rainfall runs above 40 inches. Mornings bring heavy dew that soaks anything at ground level. Then winter delivers freeze-thaw cycling that works on every gasket and seal. And if you're near the Bay, salt in the air accelerates corrosion on metal parts and electrical contacts.
Add irrigation to that picture, since most lit yards around here have sprinklers, and fixtures get hit with water daily during the growing season, often while they're still warm.
The Main Way Water Gets in Isn't the Way You'd Think
Most people picture rain leaking past a gasket. That happens, but the bigger culprit is something called thermal pumping, and it affects even fixtures that are properly sealed.
Here's the mechanism. When a fixture is on, it warms up and the air inside expands, pushing out through whatever tiny gaps exist in the housing. When it shuts off at midnight, that air cools and contracts, and the fixture draws air back in. In Maryland, the air it pulls in at 1 a.m. is close to saturated. Do that every night for a season and the moisture accumulates inside the housing. When the lens cools below the dew point, that moisture condenses on the inside of the glass, where you can't wipe it off.
This is why a fixture can be rated for wet locations and still fog up. It was never submerged. It breathed.
Quality fixtures address this in one of two ways: a sealed, gasketed design with a drain path at the bottom so any condensation escapes, or a small vent that lets air move without letting liquid water in. Cheap fixtures do neither. They trap what they take in.
The Other Entry Points, In Order of How Often We See Them
Wire splices. This is the number one cause of real water damage in low-voltage systems. Twist-on wire nuts and electrical tape are not waterproof, and buried in Maryland clay they'll wick water into the connection within a season or two. You want gel-filled or silicone-filled direct-burial connectors, rated for the purpose.
Capillary action up the cable. Once water gets into a nicked cable jacket or a poorly sealed splice, it doesn't stay put. It travels along the strands inside the wire, sometimes for feet, and ends up inside the fixture housing or the socket. This is the failure people find baffling, because the fixture looks perfectly sealed and it's still full of water. The water came in through the wire.
Corroded or aged gaskets. UV exposure and heat cycling turn rubber gaskets brittle. A gasket that was watertight at installation may be a leak path by year five, and gaskets are rarely inspected until something fails.
Fixtures buried in mulch. Every spring, a fresh layer of mulch goes down and a few fixtures disappear into it. Now the housing sits in a damp, decomposing sponge that holds water against the seals and blocks the drain path. This is a big one in Maryland because we mulch heavily.
In-grade and well lights. Any fixture installed flush with the ground is essentially sitting in a small bucket. Without a proper gravel sump beneath it and a working drain, it fills. These fixtures need the most careful installation and the most regular checks.
Thermal shock on hot lenses. A sprinkler zone firing cold water onto a warm lens can crack it. Once the lens cracks, water is inside the fixture on the next rain. This is one of the real coordination points between irrigation and lighting in the same yard.
Transformer knockouts and the outlet. Unsealed knockouts in the transformer cabinet let in moisture and insects. So does a receptacle without a proper in-use weatherproof cover.
How to Tell Moisture is Already a Problem
- A fogged or beaded lens. Condensation inside the glass is the earliest visible sign.
- Flickering or intermittent operation. Often a corroded connection or a compromised socket.
- A fixture that's noticeably dimmer than its neighbors. Corrosion increases resistance.
- Green or white crust on connections, sockets or fixture bodies.
- A GFCI that trips after rain and resets fine when things dry out. That's a ground fault somewhere in the system, and it will get worse.
- A zone that fails in spring after a wet winter, having worked fine in fall.
How to Keep Water Out of Outdoor Lighting Fixtures
Specify fixtures built for this climate. Solid brass and copper handle Maryland humidity and Bay salt far better than painted aluminum or plastic, and they hold their seals longer. This is the single biggest quality difference between a system that lasts 15 years and one that starts failing in year four.
Insist on waterproof connectors at every splice. Gel or silicone-filled, direct-burial rated. If a contractor is using wire nuts underground, that's a shortcut you'll pay for later.
Keep splices accessible. Where practical, connections should be above grade or in a small valve box, not buried at an unmarked depth in the middle of a bed.
Use drip loops. The wire entering a fixture should dip below the entry point so water running down the cable drips off rather than following it inside.
Protect the cable jacket. Nicks from shovels, edgers and trenchers are entry points. Cable should be buried at proper depth and routed away from areas that get dug up.
Give in-grade fixtures real drainage. A gravel sump underneath, and a check every year to make sure it's still draining.
Keep fixtures out of the mulch. Raise or reseat them every spring. It takes minutes and prevents a slow, invisible failure.
Coordinate sprinklers and lighting. Adjust heads so they aren't spraying directly onto hot lenses, and don't water while the lights are at their warmest.
Run your lights regularly. This is counterintuitive but real. A fixture that runs every night warms up and drives off accumulated moisture. Systems that sit unused for months are more likely to hold water.
Seal the transformer. Sealed knockouts, an intact door gasket, and a weatherproof in-use cover on the receptacle.
What to Do About a Fogged Fixture
If the fogging clears during the day and comes back at night, you're probably looking at normal condensation, and it's worth watching rather than panicking.
If the lens stays fogged, or you can see standing water or corrosion, the fixture needs to be opened, dried, inspected and resealed with a new gasket. Check the socket and the wire entry point while it's apart, because that's usually where the damage is. If water has traveled into the cable, the affected section of wire and the splice need to be replaced, not just dried out. Drying a wet connection without fixing how water got there just delays the next failure.
The Short Version
In Maryland, your fixtures are going to encounter water constantly. The goal isn't to keep them dry. It's to make sure that whatever gets in can get back out, and that the paths water uses to travel: splices, cable jackets, gaskets and mulch beds, are sealed, drained and maintained.
Fixtures chosen for this climate and installed with waterproof connections will handle our humidity for years. Fixtures chosen on price will not, and you'll usually find out about it in the third or fourth spring.
Let TLC Take a Look
Moisture problems are easier to prevent than to chase. The fixtures we install are chosen for this climate, the connections are made with waterproof, direct-burial connectors, and the wiring is routed and protected so water has somewhere to go instead of somewhere to travel.
We also service systems other companies installed. If your lenses are fogging, a zone keeps dropping out after rain, or your GFCI trips every time it storms, we'll find where the water is getting in rather than just swapping the fixture and waiting for it to happen again.
TLC has been designing, installing and servicing outdoor lighting across Maryland for over 40 years. Request a free lighting evaluation or call us at (301) 603-3097.
Frequently Asked Questions
Why is there condensation inside my landscape light?
Usually thermal pumping, not a leak. The fixture warms up while it's on, pushes air out, then draws humid air back in as it cools. In Maryland that incoming air is close to saturated, and the moisture condenses on the inside of the lens. A properly sealed fixture with a working drain path handles this. A cheap one traps it.
Is a little fogging normal, or does it mean the fixture is failing?
If the fogging clears during the day and returns at night, that's normal condensation and worth watching rather than fixing. If the lens stays fogged, or you see standing water, corrosion or a crust on the connections, the fixture needs to be opened, dried and resealed.
Are my lights waterproof?
Most quality landscape fixtures are rated for wet locations, which means they're built to shed rain, not to be submerged or to keep out humid air entirely. Rated for wet locations and permanently dry inside aren't the same thing.
Does salt air near the Bay make this worse?
Yes. Salt accelerates corrosion on metal parts and electrical contacts, which is a strong argument for solid brass or copper fixtures on waterfront and near-water properties rather than painted aluminum.
Should I turn my lights off to protect them from moisture?
No, the opposite. Fixtures that run regularly warm up and drive off accumulated moisture. Systems that sit unused for months are more likely to hold water.
Can a fogged or water-damaged fixture be repaired, or does it need replacing?
Often repaired. Opening, drying, inspecting the socket and wire entry, and fitting a new gasket handles most cases. Replacement makes sense when the housing is corroded through, the lens is cracked, or the fixture is a low-grade one that will simply do it again.
