Breathable or sealed Fixtures??

[Eden Lights]

Most accent style landscape fixtures appear to allow condensation out of the fixtures by keeping the wire way open, allowing expanding air from the heat of the lamp to escape. When the lamp is shut off the moist air is drawn back into the fixture and the process starts all over again. My concern is when the fixture is mounted on tree mounts or down light applications the moisture is allowed to collect in the compartment behind the lamp. What I have been doing on my installs is making a drip turn with the wire at the entrance to the fixture and filling the fixture wire way with sealant or trying to spec a fixture with a sealed wire way. What are others thoughts on sealed vs. unsealed fixtures?? How do you combat moisture entry on open fixtures??

[sitelights]

There are two separate issues here: airtight and watertight and low voltage lighting luminaires for other than underwater use are neither. Airtight is not a design goal in low voltage fixtures. Watertight is a design goal but this is to exclude penetration of rain or water from lawn sprinklers and not the immersion that sometimes occurs in low lying portions of a landscape subject to occasional flooding.

The heat/cool cycle will draw in moisture laden air which then condenses on the cool interior surfaces and subsequently is driven off by heat from the lamp. This is normal and the amount of water in the fixture body is minimal and does not progressively accumulate. Water leakage is another matter entirely and a fixture cavity will eventually fill to its spill point unless there is a drain hole or a gasket at a low point that allows water to weep out of the body.

It is a mistake to use a luminaire as a downlight if it is not designed as a downlight. As a case in point I installed 14 Hadco BL616s on an arbor covering a 40' pathway to a deck. I anticipated water penetration and filled the stem of each with silicone seal and made a drip loop on each lead wire. All 14 of the fixtures filled with water over the course of one summer and three instances of remedial action were attempted: the 616s were disasembled and sealant was applied from the inside around the wireway; then duct seal was packed into the underside of the mounting canopy; finally I replaced all 14 of the 616s with 14 of Hadco's DRL2 downlights.

The DRL2 has a watertight compression fitting at the top of the domed fixture body and is hung from a gimbal that does not penetrate the unit. This was a more than $1,000.00 fix (at my cost) and an error that has not been repeated. The 616s all had ruined sockets so what I salvaged were the lens/gasket assemblies that were intact and never leaked. I could have taken the lenses out of the gaskets and let the fixture drain itself (since I use front cover MR-16s) but that kind of cheap and dirty fix does not meet my standards.

If by "open fixtures" you mean a type of fixture that is not entirely closed i.e. a unit that uses a bare PAR lamp, these fixtures usually drain to the earth as in an ABS tube well light or have a drain hole at the low point of the body.

To summarize: condensation is unavoidable; leakage is avoidable if the correct fixture type is spec'd.

[Eden Lights]

By open I was talking about the wireway and the front of the lamp area. I understand that the sealed lamps fix the open lamp area that is exposed to the wireway such as a Vista fixture. I guess my main concern was the need for a down light that was water tight such as the Lumiere fixtures. Janet Moyer says the first test should be a run through the dishwasher, I bet that would weed them down to just a few?