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Thread: Shop ceiling height and lighting

  1. #1
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    Shop ceiling height and lighting

    I'm planning to start building a shop near the end of this year. Main room size is ~20'*30' with two attached 1 car garage bays for overflow . Location is south Texas, where AC is the primary operating expense, but heating is required maybe 2-3 months a year.

    The current plan has a 10' flat ceiling, but I have been contemplating going with a cathedral ceiling (spray foam and wallboard on rafters) and putting a loft up over the attached garage bays ~ 24'*30' loft, with maybe 1/2 the loft space lost due to roof pitch and knee wall (extra storage in the loft, who knows what goes up there,...).

    Doing the cathedral ceiling and loft may kill me in AC costs, still chewing on that, but cold air does go down so I could let the loft get warmish, particularly if it is for wood/junk storage. I'm thinking mini-split for the AC/Heat, but my current builder has no experience with them. I have one in my current shop and love it, very quiet and cools my garage when its 125 degrees outside.

    Should I choose a cathedral ceiling the ridge will be about 16-20' off the floor, which requires changing the lighting plan.


    • Would a single row of high bay lights on the white drywall cathedral ceiling, running down the center of the 30' long, 16-20' foot high ridge line, be adequate task lighting (i.e. able to cast 20' wide at waist high), or would I end up with too many shadows at machines along the side walls (which may be unfinished T&G pine,,,).


    I don't think I'd be happy with the look of a bunch of T8's hanging down 8' from the ceiling in a grid.
    Mark McFarlane

  2. #2
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    How many lamps in each fixture? And what style (T5HO?) high bay fixtures/lamps? Metal Halide?

    Honestly I don't think my 30,000 lumen 6 lamp T5HO lights with specular reflectors in a single row would be enough for all 20' wide - at least not to the light level I would like to run a shop in. It would be lit but you would have shadows at the edges. Id run the numbers and see what ft/candle at 36" you come up with.
    Glad its my shop I am responsible for - I only have to make me happy.

  3. #3
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    Everyone has their own ideas about how much light is enough. My shop sounds a bit like yours, a 24x62' with 22' of that a separate room with garage door bays for maintenance and machine shop, the rest for wood, office, and a small welding room, heat and air, but with 9' ceilings. I tell people I built the shop myself with my bare hands but I lie (I used tools).

    I can't imagine having enough light at the edges of the shop with lights just down the middle. But I like a lot of light.

    I looked and looked and decided on the high output T5 fluorescent fixtures. I do two things with these - I put sets of fixtures on different switches so I can turn on zones when working in certain areas. For example, I have the woodturning area switched separately from the flat wood shop which is separate from the wood storage area, etc. Three way switches let me turn on these zones from the front door or from the area itself.

    The second thing - the electronic ballasts for the 4-bulb T5 fixtures I bought have a feature built in that when activated will normally turn on only two of the four bulbs. The other two come on when a separate switch is thrown. I mounted these "extra light" switches higher on the walls and only turn them on when I really need them. Some visitors want sun glasses but I think it is perfect. (The older you get, the more light you need.)

    All my T5 fixtures are 4-48" bulbs but some are 8-foot mounted directly to the ceiling and some are 4' suspended a little from the ceiling. I put fixtures a couple feet away from the outside walls and some in the middle of the room. I have seven fixtures in the main shop on three zones, one in the 12x12 welding room, and one in the maintenance bays, augmented with some very bright CFLs.

    Another thing I did which I highly recommend after using it for a few years - I ran a string of strategically placed lower-brightness bulbs (mostly recessed fixtures) through the entire building and all on one switched circuit (but with switches at both ends of the building and near the middle). These do not give enough light for working but do let me walk through the entire building to retrieve things or return tools without turning on any of the bright working lights.

    JKJ

  4. #4
    Proximetry certainly makes a difference but it only takes a few minutes to do a quick lumens per square foot calc. Simply divide the lumen output of the lights you contemplate by the square feet of the shop. For us more experienced (i.e. older) woodworkers, 100 lumens/ft2 is recommended. I don't have half that and am pretty happy, however. But if it's only 20, you are going to want more. If it's 50, it might work. If it's 100, I think you would be in pretty good shape. And if it's lower, then spreading them around so you aren't so far from the light will also be more important. White walls and ceiling will also let the light spread out instead of being absorbed.

  5. #5
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    Quote Originally Posted by Mike Heidrick View Post
    How many lamps in each fixture? And what style (T5HO?) high bay fixtures/lamps? Metal Halide?

    Honestly I don't think my 30,000 lumen 6 lamp T5HO lights with specular reflectors in a single row would be enough for all 20' wide - at least not to the light level I would like to run a shop in. It would be lit but you would have shadows at the edges. Id run the numbers and see what ft/candle at 36" you come up with.
    Thanks Mike. I was thinking T5HO's, maybe 6 bulb fixtures similar to someone's shop I saw on this forum, I think it was yours . The 'direct path' numbers are easy enough to calculate, the shadows are a little different story.
    Mark McFarlane

  6. #6
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    If you came in 5' from each side wall you could easily light that with two rows.
    Glad its my shop I am responsible for - I only have to make me happy.

  7. #7
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    I am 27 feet wide with a Sizzor truss ceiling. Its 9 feet at the walls, and 14'6" at the peak .. Only 968sf.

    If I went right down the middle, it would basically be 13 feet to the walls on each side. I was thinking 6 or 7 of the 6 tube fixtures that Mike used. I only worry about them all being down the middle but thats the highest spot ..

  8. #8
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    Thanks John and Jim for the insight. I'm approaching 60 and will appreciate the extra light.

    I've never seen 4 bulb fixtures that let you turn on only 2. That's an awesome way to get even coverage during the daytime with supplementary window lighting, then crank up the second set of lights at dusk. My current shop plan has large windows along one side of the shop, and a few smaller 'up high' windows on the other side.

    Maybe I could do T5HOs along the ridge and a row of supplementary 1-bulb fixtures at the wall-rafter junction to prevent shadows and get closer to the machines. Anyone seen a one-light 4' fluorescent that mounts on it's side, i.e. meant for wall mounting and the reflector casts light down and out.
    Mark McFarlane

  9. #9
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    Quote Originally Posted by mark mcfarlane View Post
    ...
    Maybe I could do T5HOs along the ridge and a row of supplementary 1-bulb fixtures at the wall-rafter junction to prevent shadows and get closer to the machines. Anyone seen a one-light 4' fluorescent that mounts on it's side, i.e. meant for wall mounting and the reflector casts light down and out.
    Actually, that won't work exactly, DC ductwork will be running near the wall/rafter junction, so I'd need to move the lights up onto the sloped ceiling.
    Mark McFarlane

  10. #10
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    I only worry about them all being down the middle but thats the highest spot ..
    Before you install them permanently, if it is practical perhaps there is a way to hang a couple temporarily to check the light levels near the walls. I did that in my shop, before I put up the ceiling paneling. That helped me decide how many fixtures to use and the best placement.

    BTW, I do augment room lighting with dedicated task lighting. At certain tools, bandsaw, lathe, milling machine, etc, I wired extra outlets controlled by switches near the machine. I plug corded fixtures into these outlets so they are only on when I need them. This is especially useful at the wood lathes where diffuse, even overhead light makes it more difficult to judge the surface curves and finish.

    JKJ

  11. #11
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    Quote Originally Posted by John K Jordan View Post
    Before you install them permanently, if it is practical perhaps there is a way to hang a couple temporarily to check the light levels near the walls. I did that in my shop, before I put up the ceiling paneling. That helped me decide how many fixtures to use and the best placement.

    BTW, I do augment room lighting with dedicated task lighting. At certain tools, bandsaw, lathe, milling machine, etc, I wired extra outlets controlled by switches near the machine. I plug corded fixtures into these outlets so they are only on when I need them. This is especially useful at the wood lathes where diffuse, even overhead light makes it more difficult to judge the surface curves and finish.

    JKJ
    Good ideas, thanks John. Putting 'em up near 20' will probably require renting scaffolding, or hire it out. Switched outlets is a great idea for local task lighting.
    Mark McFarlane

  12. #12
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    My shop is 20x20 cathedral truss across ceiling. 8 ft walls with a 7 ft run to the top about 5 ft across. I have 4 four ft T8s evenly spaced on each side with one T8 on each end of the ceiling with a fan in the middle. I added some spot lights here and there. Plently of light.
    Don

  13. #13
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    Quote Originally Posted by Don Jarvie View Post
    My shop is 20x20 cathedral truss across ceiling. 8 ft walls with a 7 ft run to the top about 5 ft across. I have 4 four ft T8s evenly spaced on each side with one T8 on each end of the ceiling with a fan in the middle. I added some spot lights here and there. Plently of light.
    Don, Is that 2 rows of four 4-foot T8s, with 5 feet between the 2 rows, and they are 15 feet of the floor (or if the 7foot run is at a diagonal, maybe 13 feet off the floor)?
    Mark McFarlane

  14. #14
    Have you read my Article on shop lighting? It answers your question.

  15. #15
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    Quote Originally Posted by Jack Lindsey View Post
    Have you read my Article on shop lighting? It answers your question.

    Great article Jack.
    Glad its my shop I am responsible for - I only have to make me happy.

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