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LED recessed lights

Alan Afsari | Posted in General Questions on

We are building a home in zone 5. There is a large cathedral ceiling with a current insulation plan to be flash and batt (flash and fill – with BIBS insulation. 

We are considering using LED downlights that have a separate driver. 

I have 2 questions — one performance question and one about general lighting-

1- extension cables are available so the driver can be installed remotely – would avoiding driver installation in the ceiling help with performance?  I would think that adding heat to the ceiling would be undesirable. The luminaires are air sealed and there is a gasket on the perimeter. 

2 – the ceiling is pitches 1.5:12 on one side and 2.5:12 on the other – I was told that we need to use gimbal fixtures or the light won’t be directed towards the floor properly. Is that true for such a low pitch?

Thanks,
Alan

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Replies

  1. Trevor Lambert | | #1

    Where exactly would you place the drivers? The heat of the whole unit is not a lot, and the majority by a pretty wide margin comes from the LEDs themselves.

    I wouldn't worry about the gimbals. If these are standard lights, the cone of light will be something like 60 degrees.

  2. Jamie B | | #2

    I have a 2.5% slope on a ceiling that spans from 11' height at one end and 10' height at the other.

    I have 4" led lights without gimbals and the angle is not noticable at all.

    I'd also like to know where you're putting the drivers

  3. Expert Member
    Akos | | #3

    Alan,

    The drivers are IC rated, they can be covered with insulation. They will last a bit longer if they are in free air but that is typically more work than it is worth.

    I would stay away from the gimbals, they are not as air tight as the fixed units. Fixed is not a problem on low slope, I have it in sloped ceiling of my bathroom, you might have to adjust the fixtures a bit down the slope so the hot spot ends up at the right point in the room.

  4. Expert Member
    Dana Dorsett | | #4

    >"...we need to use gimbal fixtures or the light won’t be directed towards the floor ..."

    Bad thinking. Talk to a real lighting designer. In many cases you'd be better off directing it toward a wall, not the floor. A 1950s style "sea of ceiling lights" approach isn't the best bet for most residential applications.

    Relying on downlighting for setting ambient light levels delivers less function due to high glare. Glare is defined in the lighting design world as the contrast between a light source and it's surrounding field. Visual acuity is negatively impacted with high glare lighting, requiring higher light levels to achieve the same functional vision, in part due to glare causing pupils to constrict, with less light actually reaching the retina, but with downlighting there is also the effects reduced illumination in the unavoidable shadows.

    Balancing downlighting with uplighting to illuminate the surrounding field mitigates against these affects. Downlighting positioned next to a wall for a "wall wash" effect also fills in shadows and enhances visual acuity at a given ambient light level, but only partially reduces glare effects.

    Treat yourself to a primer on lighting design by surfing the Rensselaer Polytechnic Institute's Lighting Research Center before finalizing any lighting strategy & plan.

    https://www.lrc.rpi.edu/

    https://www.lrc.rpi.edu/programs/DELTA/publications/residential.asp

    1. Expert Member
      Akos | | #5

      Wrong, Wrong, Wrong

      You need the glare to hide the shabby workmanship and never put pot lights near walls as you can see the bad taping job.

      On a more serious note, the slim LED pucks have a pretty wide light cone and do a decent job of filling a room with minimal shadows. My biggest issues is that get a decent coverage you need to put in too many and they can make the space too bright. Dimmers are usually a must, getting dim to warm units also helps.

      Proper lighting design is not easy, getting proper fill/task/accent lighting takes a fair bit of effort and $$.

  5. Alan Afsari | | #6

    Thanks for advice.

    We have a closet on the other side of one of the walls, the drivers could be stored there and the cables could be run between the I-joists... sounds like it isn't important to store them out of the ceiling.

    I'll read over the links that Dana provided...

    Hopefully we'll come up with a decent plan... if we go with the sea of ceiling lights, we'll consider a chase for for the drivers and the fixtures - and dimmers too.

    I like the idea of up lights, but there are beams parallel to the ridge beam and we would probably need to have some sort of cove lighting system on the high side of each beam - worried about how that would look.

    Thanks
    Alan

    1. Expert Member
      Akos | | #7

      Alan,

      Wherever you put the drivers, make sure they are accessible as they do occasionally go. If you put them in the rafters, mount them near the LED hole, just don't mount them too tight so you can just reach up, unhook and pull them out if needed. Depending on your electrical inspector, they might be ok with just leaving the driver beside the opening above the drywall.

      If you have collar ties, something like this works great for uplights (I have a similar setup):

      https://s3.amazonaws.com/cdn.ecolocityled.com/images/uploads/ultra-warm-strip-lv2-500.jpg

      Otherwise some other ideas for wood beam ceilings:

      https://ls.lighting/exposed-beam-lighting-design/

      Be careful with any low angle lighting along a flat surface. Even the smallest imperfections will show (by small I mean even dust).

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