LED Ceiling Lights

The "Commercial Electric T91" or more correctly, the Lighting Science Group (LSG) 'Glimpse'.



Home Depot sells this under the brand 'Commercial Electric' model 'T91'. Let's be fair, a lot of electrical supply houses are only repping LED fixtures that are very expensive. Lowes isn't really paying attention to LEDs at all, and Home Depot has embraced them. Fair is fair. I'm no fan of 'Big Box' shopping, no, not at all. But we're still at the forefront of energy sensible lighting for the home, and most folks are ignoring it. The National Electrical Code certainly is, but more on that later.

I paid $35+tax for these fixtures. 750 lumens, and I forget what the color temp is, but it's not awful. I was looking at installing the Home Depot "Eco Smart" (a horrible brand name is ever there was one. Anyone who can sell a product with that insanely idiotic packaging, and call it 'Eco Smart' deserves some kinda irony award.) downlights. Bob had installed these in his kitchen. He replaced 5 60 watt downlights with these, took him maybe 10 mins per fixture to do the conversion, and in the end, the lighting is smooth, at least as bright as before, maybe a bit more, and uses about 1/5th the energy.

Anyway, I didn't really want to put ceiling lighting in. The ceiling is already low, I didn't want to use back-cans to mess up the insulation, throw heat into the attic, blah blah blah. But folks convinced me I really did want light, lots of light in that space when it was finished. I (as always) begrudgingly agreed and started searching for suitable lighting, when I stumbled onto this light. According to the packaging, it will install into a 5" or 6" back can, OR a 4" J-Box. So, I bought one and a 4" junction box, and tried it. Yeah, it fits. So, I tried it with a ceiling box, and yeah, it /just/ fits. So, I tried it with steel ceiling boxes, double-stacked, and that seemed to be the trick. It /just/ fits, along with a generous mittenfull of interconnecting and wirenuts and what-all.

So, here's the story of the LSG Glimpse/Commercial Electric T91 at Cold Comfort.



What's in the box. Everything you need. The luminaire assembly (Why do electricians use that word?) has all the goodies already in place *if* you were installing into a back can. So, we have to take it all apart and fiddle with a few things in order to shove it all up into a ceiling box.



First up, pop off the trim ring, and back out the two mounting screws that secure the lamp 'disk' to the electronics/mounting assembly.



In every case, the UL cert sticker occluded the slot for one of the mounting screws. So, one has to peel back the UL sticker (or just shove your way through it) in order to separate the assemblies.




I don't like messing with UL stickers, I keep thinking the pillow-tag police will kick in my door in the middle of the night. Anyway, moving along:



with everything loosened up, the springs for the back-can mounting pop right off, then you may untangle all the ground wires. The build quality of this fixture is really very nice. Not like some of the junk we've all come to expect from residential (and some commercial) lighting fixture, where low-cost, high-price, big margins seem to rule the roost.



The fixture mount, and integrated electrics, LED driver assembly, and some other magic box, I'm supposing it has to do with the ability of this LED to be dimmed with a dimmer switch, and line filtering to handle the predicable hashing mess that would create. Anyway, that's all conjecture, I didn't smash any of these into pieces to see what's inside.

I have to change a few things to get this to work in my ceiling box.



First up, remove the ground connection for the (I'm guessing) line choke that dangles off the back of the driver assembly, and then move it over to the other side of the mount, and double up with the ground wire tail. This allows the choke to lay across the top of the driver assembly.



Tada! Okay, now I can install it.



A lot of ya'll will think I'm insane. But I'm old enough now to have re-done work that was done during my lifetime because the work got old and failed. Yes, even electrical work, that was done correctly, by the codes of the day (and when it comes to residential wiring, that ain't changed a lot, not at it's core). I've been using conduit and stranded THHN for everything thus far. I know I won't be able to hang on until the end that way, but I'll take it as far as I logically am able. Also, I use anti-oxidant compound on EV-ER-RY connection. Yes, every single one. This is a habit I got into working in marine electronics years back. In those conditions, I don't care what your conductor material is, it WILL corrode if there is a voltage potential present. Yes, even gold multipins. Impossible? No. Anyway, moving along:



See? stranded wire. Anyway, I'm using a triple stacked ceiling box here, because at this junction, I had anticipated 2 3-way switches and a 4-way switch. But I had a last second attack of common sense, and home-ran the switch boxes back to the main junction box, and did all the wiring there, instead of in the ceiling box. And that also explains the 3/4 conduit (smurf tube) here. I didn't need it.



There, all connected up, and tucked up tight into the top of the box. This will all work just fine, but there really isn't much extra room. There is enough room. But you have to keep things tidied up.



attaching the tails.

These tails are AWG 18. I'm feeding them with AWG 14 thhn. I /could/ be feeding them with AWG 16, but nooooooo. Code doesn't provide for low power "luminaires" in cases like this. I could go on and on about code vs actual needs, and how the waste in built into the entire system, but I won't do that here, perhaps at another time I can rant and rave about that.



Ground attached, and ready to install the mount/electronics.



There, all neat and in the box. Careful attention paid to not pinching any wires against the sharp edges of any of the box surfaces.



Connect the lamp assembly to the pigtail, and again, careful attention to pinched wires, and slide it onto the mounting screws.



The reveal!

these things are seriously bright. I'll need dimmers.

There are two lighting 'zones' here, and all 9 of these running at full output are (according to my amprobe, which I don't trust) drawing 1 amp at 120vac.



anyway, as you may notice, there is no ceiling up yet. Why on earth would one install the lights before the ceiling was closed? Well, a few things. One: the lights come right back down. You'll note that the lights are all sitting kinda akimbo, this is due to the fact that they are not fastened securely, so I can take them right back down. Another reason is I wanted light while I work on other stuff, and I had the lights. Another reason is there is still some science to do.

See, there is no mention made of the suitability of installing these fixtures in ceiling boxes directly against the insulation. Or the "CI" rating doing it this way. And I had my concerns. I have no earthly idea how hot these things get in those boxes, or even in free air. I needed to find out, else I could suffer big heart-break if it became clear that things were just too tight, and made a dangerous amount of heat.



My control.

Box in 'free air' with insulation on top.



My subject.

Box packed in insulation.

after 3 hours, the result of the experiment:



This is the bottom of the XPS along the edges of the ceiling. This is my base-line temp. (note, it's about 50 degrees outside, and it's my body heat in the structure, that and some passive solar through the windows).



This is the hottest spot I could find on the emitter side of the control. Not too shabby.



Here is the hottest spot I could find on the ceiling box. it's really 79 as you can see on the max display, I didn't catch that with the camera, and couldn't it again.

This is degrees fahrenheit. yeah, that's as hot as it gets in 'open space' with that ambient temp.



This is the emitter side of the subject. Again, the peak temp is on the max display. Yeah, a packed with insulation light is only throwing that much heat into the living space.



So, peeled back the insulation and quickly sought after the hottest spot I could find on the box, and this is it. Yeah, not likely to damage the insulation or the structure. All in all, I call it a success.

So, there you have it.

EDIT, UPDATE:

I said earlier that I will want to use dimmers with these lights. A bit of googling about has me doubting that. Seems folks are having trouble dimming these lights. Some claim it's all just fine, some claim it doesn't work at all, some claim it works, but the fixtures burn out. I think I'll give it a few years to sort out before I go and buy dimmers.