Thoughts on overhead lighting
joenorm
| Posted in General Questions on
It seems that recessed can lighting is pretty well agreed upon here as a bad idea.
So what is the best way to tackle overhead lighting? Can a standard round plastic junction box be made consistently airtight?
If so, what is the method?
thanks
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Replies
Joe (Sorry - I've forgotten your real name again),
A standard gasketted plastic box just needs the four wire entrances sealed with either caulking or foam.
https://www.homedepot.ca/product/nutek-round-airtight-plastic-ceiling-box/1000404482
You could go into the attic afterwards and foam the perimeter as a belt and suspenders approach if you didn't trust the gasket.
Use the fiberglass “hard boxes” (they’re usually whitish in color). These boxes have no holes or gaps around the unused cable entrances — you punch out the cable holes you need to use (they have scored knockouts). They are much easier to air seal as a result since they don’t have any leaks except the holes you put in them. Regular plastic boxes have all kinds of gaps that will leak, so sealing them is a pain. The fiberglass boxes also have fire ratings, which is nice, and they don’t cost much more than the regular plastic boxes.
Personally, I like reflective lighting (like cove lighting), but it doesn’t work in all types of rooms. Reflective lighting does avoid the need for any ceiling penetrations though.
Bill
I 2nd Malcom's suggestion. I've used those air tight plastic boxes with surface mount fixture in ceilings without issues. Very little leaks during blower door testing, not zero but pretty close.
The low profile LED lights with gaskets and spring clips also seal quite well and don't require any ceiling box.
Can lights/pot lights are just the worst offenders from an energy & moisture control perspective, but downlighting in general is completely overdone, and often not well thought out. For general ambient lighting there is better visual acuity at lower light levels using wall-washes and uplighting, using the walls and ceilings to deliver glare free shadow free illumination. While some situations may only allow downlighting, wherever possible mixing up-lighting in combination with some down lighting reduces the glare and shadow issues.
Zephyr7's preferred cove lighting is a great example of uplighting that takes advantage of both wall & ceiling for delivering the light, and can work well in most open rooms. Cabinet-top lighting in kitchens in combination with under-cabinet task lighting can also work well even with NO downlighting supporting the ambient light levels. The under cabinet task lights work better if placed away from and directed toward the wall so that the reflected light can fill in the shadows that are inevitably cast on the countertop work space with down-lighting.
Take the time to design the light rather than hack in a bunch of downlights and call it a day- it can really make or break the feel of the room. The Rensselaer Polytechnic Institute's Lighting Research Center website has a lot of useful material accessible to newbies, and worth reviewing before finalizing a lighting scheme for a given room, particularly their short residential example publications:
https://www.lrc.rpi.edu/programs/DELTA/publications/residential.asp