Energy-Efficient LED Light Fixtures
Hello fellow Green Builders,
I’m building a 2400 sq ft spec home in Blaine, WA (climate zone 4) and need some advice on a lighting fixtures. I have a goal of achieving at least 2 ACH50.
I’ve used j boxes in the past with surface mounted down lights. This allowed me to caulk, tape and spray foam the penetrations in the j box itself as well as around the j box.
I dismissed the spring clip LED fixtures in the past because I thought they would not be airtight. Upon doing some research I’m seeing the HALO lights made by Cooper Industries are listed as airtight.
https://tinyurl.com/y5xdjaw9
I found rebranded lights on Amazon that also come with a gasket.
https://tinyurl.com/yyzayqxw
Would the regular j box still be the superior approach or are these spring clip lights worth a try?
What is everyone else using for their light fixtures when building super tight homes?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
The spring clip lights are great. I'm planning to use them throughout my upcoming build.
Regarding air sealing, my plan is to use 2" R8 exterior rockwool insulation to eliminate condensation on the sheathing and detail my sheathing as my air and vapor control layer. Then 2x6 advance frame walls 24"OC and no vapor barrier/retarder. The latex wall paint satisfies class III vapor retarder req in this scenario. If you seal the sheathing well and all exterior penetrations your blower test should be great. Another approach is just to install a smart vapor retarder like Certainteed Membrain then create a service cavity (insulated if you like) over it using 2x2 lumber as furring. Then your vapor control layer is protected and saves you a ton of detailing.
I don't think spring clips LEDs are very good. If you are conscientious with every light, then great. The problem is consistency of a dozen or so lights. With a jbox light you seal the jbox and can do a blower door test and find out if any of them leak and remedy it. Replacing the lamps won't affect it after that.
These LEDs can have a blower door test but if you replace or need to adjust them for any reason then you've lost that guaranteed air seal that was previously done because the lamp themselves are part of the air seal. They just seem cheap to me but people like them because they're easy to install. They aren't a good long term investment in a high performance home like a sealed jbox would be. They'll also dump cellulose all over you when replacing them if that is your attic insulation.
Eric, this is a most basic mechanism. Simple springs clamp the light with a gasket against the drywall. A failed spring is a broken spring, which is of course easily identified. It's easy to notice if there's a defect and the light isn't seated firmly. I've never come across this personally though. You can take them out and replace them anytime and as long as the gasket and spring are fine then the seal is fine.
Aside from being easy to install, people like them for how thin they are. LED lights don't need to be bulky.
The seal and "dump cellulose all over you when replacing" issues are easily avoided if you build a small box over them. That's my plan for the vented attic portion of my current build where I'll have four of the Halo LEDs. The box is just a backup and cellulose separator more than the only seal, though I will seal the box to the back of the ceiling drywall just because I can.
I'm not a fan of most of the spring clip fixtures since they all seem too loose to me. I also don't like the "stuff the wiring in the ceiling" wiring method they need, and I don't like the ballast potentially buried in insulation. There is also the potential issue of finding a replacement fixture that will fit in the future.
The J-box type lights, in my view, are more flexible. The octagon boxes most use is a standard and has been for a very long time (100+ years), so the chances of fixtures being available to fit in the future is pretty good. You also have a nice box for wiring, with cable clamps and everything else, and nothing that needs to be stuffed up in the ceiling. The J-box lights are my preference.
In terms of air sealing, the J-box lights could potentially be a tighter fit, but I doubt all of them are. You also need a securely fastened J-box to be able to get the fixtures installed correctly. If you have a "bouncy" J-box it can be difficult to get some of the lights to snap in correctly since the box pushes back when you push on the fixture to snap it into place. I actually just ran into this recently a few days ago. It wasn't a show stopper, but it made it more fussy than it would have otherwise been to get one of the lights snapped into place.
I agree that LED lights can have a low profile though! You aren't limited to recessed cans anymore!
Bill
Thanks for that input Bill. Can you provide links to specific lights that you've used with success?
Thanks.
The most recent such light I’ve used was the Feit electric light Costco currently has on sale. I tried a few a few weeks ago ($10 each with the sale price), and was surprisingly pleased with them. When I’m done, I’ll have 10 of them installed here. They are fussy about clipping into place if you’re J-box isn’t solidly mounted, but that (and the really small ground screw) are about my only complaints. I haven’t had them long enough to know how well they hold up over time.
Home Depot’s squareish gimbal-type spots are nice too, and reasonably air tight (I don’t think they’re rated as such though). They are good replacements for the old eyeball type lights if you have recessed cans.
I tried some Juno type clip-in lights (not the J-box kind), and was very unimpressed with the strength of the clips. I couldn’t get them to stay tight to the ceiling. Note that I’ve had good luck with other Juno products, so they might have fixed this particular issue I saw.
The usual suspects (mostly Halo), make a LOT of options, and I haven’t tried them all. I much, much prefer their commercial style remodel cans over the box store kind since the commercial ones use a screw-in clamp arrangement with a screw that tightens the clamp, so they are much more secure than the snap-type clips on the version the box stores have.
No one makes an airtight rated can that I trust to actually be airtight. All the baskets that are supposed to seal to the drywall are crummy, and they’re frequently not installed on the fixture in the right place. When I use these, I put a piece of foil tape over the seam in the fixture to help seal things.
Bill
Juno had some with the box on top of the wafer where the clips were not strong enough for the weight of the wafer and box (as Bill said), I had those and returned them for the "box to the side" (wire between box and wafer) where the clips are plenty strong to keep the wafers against the drywall or tongue n groove (I think I have 60 of them, and some spares too). But, I have a flash-n-batt roof assembly (no attic) so leaking/sealing was not an issue. I have dimmers and hum on some of them. I hardly use them though, about 10 of the 60 get used regularly.
Thanks Bill, that's very helpful.
My preference is to use pancake-style j-boxes because they can be mounted without puncturing the drywall. But my understanding is with the latest changes in the NEC this no longer acceptable, the box needs to be rated to hold 50 lbs and unless the fixture base has a rated capacity the pancake box doesn't meet the capacity requirement. So I guess my second choice would be a one-gang box that is then sealed when the drywall is installed. I don't like the style of light where a hole is cut into the drywall and the fixture is mounted in that hole because it seems like keeping the insulation in place and keeping it sealed would be a nuisance.
Am I thinking about this right?
Thanks.
That "50 pound" requirement sounds like a ceiling fan box. I wouldn't expect a box intended for a small light fixture to need that BUT I'd have to check the code. I work primarily in the commercial world, so I'm most familiar with the codes that apply to commercial buildings and less so with some of the more obscure residential codes. If you need medium voltage switchgear and unit substations in a large, distributed system in a million+ square foot plant, I probably know what page the rule is on, and some of the footnotes too ;-)
What CAN be an issue is the "old work" boxes with a clamp. Some styles can be a problem. The type with a big spring clamp secured with a single screw on the back of the box can be an issue if overtightened (they can break the drywall on either side of the box), for example, even though they're one of the best if installed properly. The plastic boxes with the smaller wings at three locations around the perimeter are easier to install correctly, but leave a thick ring around the perimeter that will keep some fixtures from sitting flush against the drywall surface.
If you have access to the top of the ceiling, from an attic for example, you can get a steel "wing box" (my term), and screw the wing to the nearest floor joist. This lets you position the box at the depth you want, and gives a solid attachment. I like to use hex head sheet metal screws, usually 1" long, to mount these and a short driver extension in my drill to get the screws in. The orange store carries two ABSOLUTLY FANTASTIC extensions made by Bosch for the normal hex-type driver bits used in drills and drivers. The extension are available in 6" and 12" lengths. They are black with a blue release ring on the end that holds the driver. These things are worth their weight in gold when installing electrical boxes in tight spaces. I HIGHLY recommend BOTH of them for anyone doing a lot of this type of work.
The other type of box has an adjustable spanner bracket that goes between two joists to let you position the box where you want between structural members. These tend to give a bit bouncier box mounting, but they're better than old-work cut-in boxes if you have access to the "other" side of the ceiling drywall. Just make sure to tighten everything properly during install time so that the box doesn't shift out of position.
Bill
I'm not an electrician but I enjoy keeping up with the code.
A ceiling fan has to be in a box rated for a ceiling fan.
The 50-pound rule means you can't use old-work boxes that are supported by the drywall in ceilings any more, if you put a box it has to be screwed to a stud. The idea is if there's a box someone could come along later and replace the light with a chandelier or something. What I find illogical is that you can mount lights without a box if the fixture has a box attached, and if you do that you can attach it to the drywall any way that holds it long enough for you to get paid and get out of the building.
But what I want to do is put boxes in, drywall the ceiling, insulate above, and then put in the lights. I don't want to rely on the lights to hold the insulation in. So I'm trying to figure out the best combination of boxes and lights to do that.
DC, my choices for the "best box" would be one of the following (note that I'm not sure of a "pound rating" for any of these, I'd have to look that up):
If AIR SEALING is a primary concern, the fiberglass (usually white) "hard box" round boxes are easiest to seal since they are molded in one piece with no gaps (you break out thin spots for wire to enter). They are rigid, not flexible like the blue plastic boxes, pretty strong, and have a fire rating. You can get them with nailing wings on the sides. These are my favorite type of boxes for most retrofit work in exterior walls where air sealing is important since you ONLY have to seal the area where a wire actually enters the box -- there are NO other gaps or holes to worry about.
Metal octagon boxes are strong, and the mounting wings are easy to install with screws as I described earlier. I've installed lots (and lots) of these in basements, attics, and crawlspaces for lights, but they're good for many other things -- even simple junction boxes if you use the kind with built-in cable clamps on either side. If you use these for any kind of LED fixture, I would get the 2-1/8" "deep" versions which will give you more room for the little ballast bump-out on the back of the LED lights. These boxes have lots of holes and slots so they're more effort to air seal than the fiberglass "hard boxes".
There is also a "Madison box" which is handy for old work renovation applications since it has angled mounting screws INSIDE the box. you can install these types of boxes to a stud in a wall or ceiling in a hole no bigger than the box itself. These boxes are expensive compared to the others, but they're strong, and the unique mounting arrangement is very helpful if you don't want to do a lot of drywall work around a box you're retrofitting. I've used these to enlarge switch boxes before where I can pull the box apart inside the wall, cut the opening one or two gangs larger, then run the existing wires into the new box and mount it to the stud. I don't know of any other type of box that can mount to a stud in an existing wall without opening up and then patching the drywall around the box.
I try to always use the "deep" (2-1/8") versions of boxes anywhere I can since they make wiring much easier due to the increased space inside. There are codes about "fill", so if you have a lot of wires you're required to use larger boxes, but the bigger boxes make things easier even if you aren't required to use them. The larger boxes don't cost much more than the "regular" boxes.
Note that a trick I've used before to get a solidly-mounted ceiling box is to put in a piece of 2x4 blocking "sideways" and then mount a box to the face of that 2x4 through the holes in the back of the box. Use screws to mount the box to the 2x4, screws or nails work fine to mount the blocking to the adjacent joists. The result is a box mounting that is FAR more rigid than the spanner-type box mounts, and should handle plenty more than 50 pounds.
If I were planning to mount a chandelier (and I have two big 9 light chandeliers over my dining table), I would use a ceiling fan box for added strength. In my dining room, the two chandliers are mounted this way, and the boxes are mounted with VERY (I think 7 inch, it's been a few years) long structural screws into the rafters. The ceiling in the room is a catherdral ceiling, but only one half of it is the actual roof, the other half is angled opposite the roof to make a symmetrical cathedral ceiling, but there is attic space above. Think of the "devil's triangle" of a cape cod style home, but in a diamond shape due to the angled "floor" of the attic space. It's very, shall we say, "interesting" to work in that attic space...
Bill
My preference is junction boxes with surface mount lights. Either can work fine, but there are advantages to j-boxes if you have the choice. For one that makes it easy for a future retrofit of not just a replacement light, but a completely different style of light. And it avoids the need to DIY a box over it to hold back the insulation, as well as the need to rely on future electricians paying attention to air tightness.
There are surface mount lights available these days that are very low profile. And in fact, the light distribution in the room is better with a dome that hangs down just a bit: that helps you avoid having a dark ceiling.
LED wafer against drywall on ceiling, over about 200 degrees can't get my fingernail between the wafer and drywall over about 160 degrees, just barely. For assurances, seems like it could be sealed with a thin gasket.
Rope caulk works for this. I've found the gaskets all tend to be too thick and result in a noticeable gap around the perimeter of the fixture.
Bill
Thanks Bill, good solution, I have a box of rope caulk, bought on a whim, and was thinking of possible uses ;-) Brian