Why is there water inside my outdoor light?

Rubber seals and gaskets harden and crack after years of sun, so a fitting that was weatherproof when new may not be now. Lenses crack from heat, hail or a stray ball. Water also follows the cable in if the entry point wasn't sealed, or runs down the wall behind a fitting that wasn't sealed to it. Some fittings are only made for covered spots such as a porch or under the eaves, and leak when fitted on an exposed wall.

A light's weather rating is shown as an IP number on the fitting or its packaging. The second digit describes protection against water, and a higher number means better protection. Fittings near the bay in Altona, Seaholme and Williamstown also face salt air, which corrodes screws, seals and terminals faster than further inland.

Water lets current leak from live parts to earth. A safety switch watches for that leak and cuts the power in a fraction of a second, which is the switch doing its job. If it trips after rain and resets once the fitting dries out, the fault is still there and will come back. Resetting it again and again isn't a fix.

Sometimes a fitting can be resealed, but if water has been sitting inside, the lampholder, driver or terminals are usually corroded and the fitting should be replaced. The lasting fix is a fitting rated for the exposure, mounted the right way up, with the cable entry sealed. Replacing an outdoor light is electrical work for a licensed electrician, and you get a Certificate of Electrical Safety for it.