Replies

1. 
   saschafer | Apr 12, 2008 03:17am | #1

   Metal halide lamps are very efficient (a bit more efficient than regular fluorescents, and about the same as high-efficiency fluorescents), but best for applications where they're on for several hours at a time. You can't turn them on and off at will--they need several minutes to warm up, and after you've turned them off, they need several minutes to cool down before you can turn them on again. They also give point-source illumination, so they cast harsh shadows.

   I've found that continuous rows of two-tube T-8 fluorescents, spaced 4 ft apart, give me good overall illumination. The lighting is very "flat," so there's no problem with shadows. I would decrease the spacing to 2 ft (or, alternatively, switch to 4-tube fixtures) over a workbench or other "close work" area. That's the setup I have now--two 4 ft-long four-tube fixtures, 4 ft apart, centered over the bench. One is positioned more or less directly over my head when I'm standing at the bench, and the other one is over a point just beyond the far side of the bench.

   -Steve

    

2. 
   MrBill | Apr 13, 2008 02:41am | #2

   dc,

    I am in the same situation at my business. I do have 2 metal halides, but they really are not what I thought they would be as far as light goes. A customer was in the other day and mentioned the lighting to me. He had jsut finished wiring a warehouse across the street and told me to go look at it. I think he mentioned 4' T-8's.  I am goint to try to take a look at the place next week if I am not too busy. I think any good electrical supply house should also be able to give you some ideas. I have to do something soon, I am getting tired of working in the dark :)

   Bill Koustenis

   Advanced Automotive Machine

   Waldorf Md

3. 
   Tinkerer3 | Apr 14, 2008 07:14am | #3

   I use eight four tube 4 ft. T5 fluorescent units in my shop.  I have one unit for every 120 square feet of shop.  I like lots of light and have that - probably could get by with less.  I have five 3 X 5 ft windows in the shop but I consider them a waste of light and heat.  If I were to do it again I would consider less and much smaller windows as I have to turn the lights on anyway.  I might have gotten by with the T8 fluorescent lights but how could I tell without taking the existing ones out and replacing them with the T8s.

   
   

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   Edited 4/14/2008 12:15 am ET by Tinkerer3

1. 
   dcpokemytoes | Apr 16, 2008 02:03am | #5

   Anybody know the difference between t-5 & t-8?

1. 
   Tinkerer3 | Apr 16, 2008 04:58am | #6

   Not an expert on this but the t rating refers to the diameter of the tube, also the brightness.  I think the t-8 is 32 watt whereas the t-5 is 54 watts.  I have both and although I haven't paid particular attention, I think the t-5 is quite a bit more expensive.  I also think the old t-12 is on its way out if not already there.

2. 
   saschafer | Apr 16, 2008 05:49am | #7

   This is part of an old, old naming system for bulb sizes. The letter gives the type (T = tubular) and the number gives the diameter in 1/8ths of an inch. Conventional fluorescents are T-12's, the newer high-efficiency ones are T-8's, and the even newer extra-high efficiency ones are T-5's (there are also some specialty T-6 tubes that fit in T-5 fixtures). The T-8's and T-5's generally have better color rendition indices, too, so the light looks more natural.

   There are also miniature T-4 and T-2 fixtures.

   -Steve

    

3. 
   RickL | Apr 17, 2008 11:36pm | #9

   http://www.lightingtaxdeduction.org/technologies/t5.html

   We have several types of T-12, newer T-8 as well but these T-5 are super bright and the frequency is close to sunlight. I was talking to a car dealer who is puttin them in the showroom to make sure the car shows the true color. Also know of an Architect using them with a dimmable ballast so when full sunlight is available they automatically dim to conserve power.

   The other option is a dimmable ballst to change the light intensity. T-5 is the newest development over the T-8.

   T-5 high output is the one I have from Spectrum lighting

1. 
   andyfew322 | Apr 18, 2008 04:27am | #10

   I think we have those in school, very even light, with no shadows

   In shop class though, we just have florecent

     

   Look ma, no jigs!!!

2. 
   Jfrostjr | Apr 18, 2008 03:32pm | #11

   Does the T-5 require a special fixture? I have T-8s running, high, down the center of my shop - but have "old style" fluorescents running down each side. Can I install T-5s in those fixtures?Frosty"I sometimes think we consider the good fortune of the early bird and overlook the bad fortune of the early worm." FDR - 1922

1. 
   saschafer | Apr 18, 2008 05:40pm | #12

   No, T-5's will not fit in T-8 (or T-12) fixtures. They're actually not quite the same length, and their ballast requirements are different.

   -Steve

    

2. 
   Jfrostjr | Apr 18, 2008 06:28pm | #13

   Thanks. I guess I'll use up my supply of 'standard' bulbs before I make any changes.Frosty"I sometimes think we consider the good fortune of the early bird and overlook the bad fortune of the early worm." FDR - 1922

4. 
   RickL | Apr 14, 2008 04:49pm | #4

   We are upgrading our lighting. Tried a 400 watt metal halide. The T-5  four bulb fixture blew it away. 5900 K 96 CRI  T-5 is the latest since the T-8.

   http://www.fullspectrumsolutions.com/commercial_lighting_fixtures_35_ctg.htm

    

5. 
   boilerbay | Apr 16, 2008 06:06pm | #8

   Shadows are not a bad thing when you can put the highlights and shadows where you need them when you need them. Those shadows are what shows you the difference between the band saw blade and your fingers.
   Open bulb fluorescence at what ever wattage are fine for general illumination with "open shadows" but for detail work (dovetails, surface finishes, fine joints, rules etc.) a higher attenuated light is generally considered desirable. Any form of attenuated light (vs. fluorescent ) will do - a flood, spot ,arc etc. will do.
   The main reason is in attenuated light the rays are concentrated along the path where fluorescence light is going out in all directions and bouncing back which is why they give a soft diffuse light. Spots etc, will enable you to perceive more fine detail in the same manner as your depth of field is low during twilight vs very sharp at high noon. The more lumens we have hitting our eyes - especially as we age, the more our iris contracts resulting in more depth of field = better sharpness and detail.
   Put a standard hardware store clamp reflector and bulb in front of you at a low raking angle and look at your work or from a 45 degree or less or from the backside of a spinning table saw blade and notice the difference in being able to see the blades and it's danger. Or just what the edge of that newly sharpened chisel looks like. Cross light is also what shows your textures. fluorescence are very poor for that.
   Move it around the shop to different work stations and where you do the most detail work and it will give you some good points to add task lighting to your fluorescence. (a "130 watt" - 30 watt daylight compact fluorescent bulb in a polished reflector also works although not quite as well as a incandescent.)
   A few well place tasks oriented attenuated lights help more in the shop with less eye fatigue than a total fluorescent ceiling.