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Joined: Oct 2000
Posts: 3,682
Likes: 3
Admin Offline OP
See Vapor-proof A luminary filled with water, socket submerged.
A) Perhaps more than a Vapor-proof gasket issue?

[Linked Image from]

[Linked Image from]

See Vapor-proof B partially filled by condensation with burnt lamp.
B) Perhaps a typical Vapor-proof gasket leak?

[Linked Image from]

Installer sandwiched 2x4's, between two J-boxes, hoping clear Silicon provides extra barrier as shown.

I'd prefer weather-tight UF connectors, wrapped directly to ceiling-mount box, since EMT with extra box could be removed.

But, vine trimming on truss may require EMT, and five identically-installed luminaries have no water penetration.

A diamond bit on glass jar bottom could also arrange jars to drain.

What say you is the best repair?


Horizontal Ad
Joined: Feb 2003
Posts: 939
I can't really say about your location however IMO you should switch over to PVC and get rid of bell boxes to neaten up a bit.

The other issue I belive that when someone install them they were not really watching the gasket when they install the luminaires. which that is pretty common failure if not installed properly or gasket get dry or get brittle and let water seep in.

Drill the glass bottom IMO it can be done otherwise lexan verison is easier to drill out { but watch the wattage rating on them }

So there are few ways you can do this the key issue is find a way to prevent any more water pentration and have proper drain fitting or drill the drain opening as need to.


Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)

Joined: Jan 2007
Posts: 36
Many Thanks Marc.

The location could be underground, since this arbor soaks in the rain, and takes days to dry.

Yes, PVC to NM conduit body would be a much better design. The metal Bell boxes also disintegrate rapidly in this area.

Thanks for describing the vaportight gasket issue. Gasket, box, & fittings could be tested by removing jars to a water bucket.

Drain holes only for stubborn condensation makes sense, since water leaks can fault, needing repair or replacement.

Best regards to you & yours.

Roger Ramjet
Joined: Apr 2002
Posts: 7,391
Likes: 7
IMHO, water is going to find any point of entry into these fixtures, no matter what you do from what I can see in the pics. The 'raintite' EMT connectors are raintite....not waterproof.

Judging from the pic, that water did not enter quickly, as it is dirty/discolored.

You may achieve a 'better' install by having conduits enter the fixture base box directly, as opposed to the top entry.

I came accross some classified location (explosion proof) fixtures that were submerged in a wet well pump station (sewage) that were half full of liquids; that seeped in via the threaded (min 5 threads) and the fixture bodies. Water finds a path!!

Joined: Jun 2004
Posts: 1,273
The water is coming directly out of the air -- not rainfall.

Folks, what happens is that the interior gets very warm and drives air out.

Then the lamp is turned off and the jar space cools.

It cools so much that it forms a vacuum effect and draws in moist air.

The vapor condenses at the bottom. The heat from the next cycle is not enough to drive off the water from the prior cycle.

Day by day, cycle by cycle the jelly jar fills up. Even WP gaskets are not enough to stop the condensate build up.

The only solution is to avoid this orientation -- or to provide a bleed hole in the jelly jar. A very touchy thing to pull off.

You'll see variation on this in cold and chiller boxes. You can slow things down, but the condensate just keeps coming.

BTW, treat your wirenuts as if they were below grade in such installs. Dip them in epoxy.

Joined: Jun 2006
Posts: 613
The space fillers in the box are also not vapour or water proof. the back box can allow water in via the hub where the emt and connector screw into the box.
If not located in a hazardous location a small hole big enoug to let water out and ants in can work for condensation.
Drilling holes in glass is a bugbear and don't bother if the glass is tempered. it will just break if you drill.

Joined: Mar 2004
Posts: 947
twh Offline
Tesla makes an interesting point. If that is the problem, it can be reduced somewhat by getting the moisture off the top of the box.

Joined: Jan 2005
Posts: 5,462
Likes: 3
Cat Servant
There are replacement globes available - they're pretty interchangeable between brands, unless you get the $8 box store specials - and some are even made from plastic.

This is worth noting, because many are of tempered glass, and those will instantly shatter into glass 'gravel' the instant your drill bit pierces them. DON'T DRILL GLASS.

In a location like this one, you're in a no-win situation. Add a drain hole, and the thing fills up with gnats.

Your best solution might be to completely do away with the globe, but keep the cage. Then, use a bulb that is outdoor rated. Outdoor-rated PAR bulbs are common, and the 'halogen' bulbs have a heavy enough glass that they just might work. The cage will just help keep flammables (like leaves) from touching the hot bulb. There might even be outdoor-rated CFL's.

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