Why do garden lights keep failing, and how do you make them last?

Garden lights live with rain, sprinkler spray and wet soil, and most failures start with water getting in. Seals perish in the sun, lenses crack, and cable entries that weren't sealed properly let moisture wick inside. An in-ground uplight near a sprinkler needs a much higher water rating than a wall light under the eaves, and a fitting rated too low for its spot will fill up eventually.

Wet electrics leak current to earth, which is why garden lights often trip the safety switch after rain or when the sprinklers run. That trip is the safety switch doing its job. Energy Safe Victoria guidance says the Wiring Rules require safety switch protection on every final sub-circuit in a home, so outdoor lighting should always be behind one.

Every joint in a garden lighting run is a weak point. Joints wrapped in tape and buried, or connectors never designed for damp soil, corrode over a season or two. The result is lights that flicker, glow dimly, or work one day and not the next.

Near the bay it happens faster. BlueScope's marine-environment guide classes Port Phillip Bay beaches from Altona to Portsea as exposed marine, and salt settles on fittings and holds moisture against screws, seals and terminals. Gardens in Altona and Williamstown get more life from brass, copper, 316 stainless or sealed polymer fittings than from plain painted aluminium.

A light sold online with an impressive rating isn't always built to it. Thin housings, weak gaskets and cable glands that don't grip the cable tend to fail first. Fewer, better fittings usually cost less over a few years than replacing a cheap set every season.

Cable gets damaged too. A spade through a bed, new edging, roots or a lawn aerator can nick cable that wasn't run deep enough or in conduit. The damage often shows up as one section of lights going dead, or the safety switch tripping in wet weather, long after the gardening was done.

Low-voltage garden lights run from a transformer that steps mains power down to 12 volts. Add too many lights to one transformer, or run long, thin cable, and the lights at the far end glow dimly while the transformer runs hot. Transformers mounted where they cop full sun or rain also fail early.

Swapping old halogen lamps for LEDs can cause its own problems, because some older transformers don't suit the low load of LEDs and flicker or cut out. A transformer matched to the LED fittings fixes that. A hardwired transformer, or anything connected to your home's wiring, is work for a licensed electrician; a plug-in kit with its own plug-in transformer is treated like any appliance.

Lifespan is mostly decided at installation. Fittings matched to their spot, joints that are sealed and accessible, and cable in conduit along paths and bed edges, where a spade is less likely to find it, avoid most of the problems above.

Care after that is light. Check fittings after winter for cracked lenses and fogging, trim plants that hold moisture against them, and tell whoever works in your garden where the cable runs. A light that has filled with water should be switched off and left closed until an electrician checks it.