The extra release of heat helps the bulbs last much longer. I was curious about this, so I phoned the engineering dept that designs these lights.
The guy was helpful, friendly and informed me that these lights are normally used for outdoor security and because they have an "eye" that automatically turns this light off during the day they are designed to run 8-10 hours on average per day. He told me if I intended to run this 24hours a day (like I do) then I should drill holes in the top, OR not install the plastic shield over the light. He said that the lights would work fine, but the bulbs wouldn't last as long if they were exsposed to long periods of heat.
He did mention that a lot of people use them to grow pot and they can tell because the bulbs wont last an entire year without ventilation around the bulb, and they ask for a new bulb under the warranty.
The last thing he said was " these lights are designed to last outside and running at night when it's cooler, with ample of fresh air circulating around it ".
From that conversation I gathered that I should drill holes in all new fixtures I purchase. This year I bought 4 new ones, and chucked the rest out.
Another interesting thing he said was " Do not over load any plugs, because the fixtures have a built in fuse, that is a "ONE TIME FUSE ONLY" which means, if the fuse is required by the fixture to stop an overload...the fixture will no longer function...
I still think its WWWWWWWAY safe than any other setup i've had....and much cheaper to operate and replace.
Skin ur dink,
Canadian_Budder : - )