Light RightComments (0)
This article is from Issue 57 of Woodcraft Magazine.
A how-to guide for a better, brighter shop
For additional task lighting solutions for your shop, go to woodcraftmagazine.com and click on online extras.
Lighting isn’t the first thing woodworkers think about when planning a workshop, but with the flick of a switch, many quickly discover that it’s the one component they can’t do without. Even those who have successfully worked out their lighting will eventually need to rethink their plans. Because our eyes gradually lose their ability to absorb light, we’ll all need about 50% more light at age 40 than we did at 20, and 100% more at 70 than at 40.
To shine a light on the murky science of workshop lighting, here’s a primer with a two-pronged plan for brightening any workspace. As you’ll see, good shop lighting hinges on two components: ambient (overall) illumination and task lighting.
After you familiarize yourself with lighting terms, you can focus your attention on the solutions that meet your needs. For a step-by-step strategy for planning out ambient lighting, including tools for appraising existing lighting, go to page 56. To augment your existing lighting and to get a grip on the new types of lights that are replacing incandescent bulbs, skip ahead to the “Task Lighting” section starting on page 58.
To make sense of package labels and to communicate your needs to an electrician or lighting designer, take a few minutes to study up on the science of lighting with the lessons below.
Lesson 1: When choosing bulbs, watch the watts, but count the lumens.
Back when incandescent lighting was the main game in town, we equated “wattage” with “light intensity.” Now that there are several new players on the field, it’s time to set the record straight: wattage is the measurement of the energy required to light a lamp (or bulb). The quantity of light produced is measured in lumens (lm). When replacing incandescent bulbs, it’s tempting to believe the “equivalent to X watts” icon on the package, but it’s better to check the fine print for the actual lumen rating (see photo, above right).
Lesson 2: At the bench, think foot-candles & luxes
To measure the quantity of light reaching your benchtop, you’ll need to understand two more terms: foot-candles (fc), and luxes (lx). As the name suggests, one fc is equal to the illuminance cast on a surface by one candle, one foot away. Foot-candle ratings still appear in building codes, but lighting calculations are often done in luxes (lx). One lux is equal to one lumen per square meter. For side-by-side comparisons, note that l lx = 0.1 fc.
Lesson 3: With lighting, “color” starts with “K”
Back when your choices were “warm” incandescents and “cool” fluorescents, you didn’t need to worry too much about color temperatures. Now that bulbs come in a wider array of colors, knowing the Kelvin temperature (K) can help you pick and stick with the light you want.
Choosing the right bulb by name can be confusing because the terms coined by manufacturers to describe their bulbs seem to run contrary to the Kelvin scale (see chart, below). If you want a warmer light, look for a lower K; for cooler, bluer light, choose a higher K.
“Daylight” bulbs are the most confusing. For starters, these bulbs don’t really replicate the sunlight during the most pleasing times of day. And with the widest temperature range, the color produced by these bulbs varies greatly from one manufacturer to the next.
Lesson 4: High K = more light, less color
The light frequency of higher K-temperature bulbs activates our scotopic vision (this is the part of our eye that is more sensitive to black-and-white contrast), causing our eyes to perceive this light as brighter. By triggering our pupils to dilate, these bulbs can sharpen vision and reduce glare. The downside is that it comes at a loss of color perception.
100-Watt “Equivalent” Bulbs
Standard Incandesccent 100W
Compact Fluorescent (CFL) 23W
Light-Emitting Diode (LED) 16W
Before you start hanging lights, it helps to do some homework. Here is the five-step strategy that I followed when I converted my 20 × 20' garage into a full-service workshop, plus some lessons that I learned since then.
Step 1: Decide on the quantity of light
Ambient household light varies from 30-50 fc (300-500 lx), but for tackling detail work, you should aim for twice that amount. For planning purposes, I estimated my needs at 75 fc. (I’m certain that my request surprised my electrician, but after listening to my stories about dovetails and microbevels, he agreed that the amount was right for such detail work.) If you’re over 50, you may want to shoot for 100 fc, especially to illuminate your workbench and most-used machinery areas.
Step 2: Pick your fixture
Because they’re efficient and inexpensive, fluorescent tubes (either T8’s or T5’s) are the first choice for ambient shop lighting. The real decision is picking the right overhead fixture. Compared to so-called bargain fixtures, better quality alternatives direct more light where it’s needed and can protect the bulbs from accidental contact. (You can compare the effectiveness of different fixtures in Step 3.)
My advice? Don’t skimp. I paid around $50 apiece for 4-bulb lensed fixtures, and still consider the money well spent. For specific advice about what to look for, see the sidebar below.
Step 3: Draft a plan
If you can find a designer, provide him or her with shop-specific details, including the shop’s overall dimensions, your desired foot-candles, fixture type, ceiling height, and work surface height, and then let them draft a plan. If you can’t, you can download Visual Basic at www.visual-3d.com, a free download, and let your computer do the hard work (see photo, above right). The program automatically calculates a plan to create an even illumination plan, but you can also adjust the fixture positions and review the illumination effects.
In order to maximize the ambient light at the workbench and tablesaw, I adjusted the fixture positions to correspond to the Fixture Placement Guidelines at right. Repositioning the fixtures to one side of my garage bumped the light at my bench and tablesaw to more than 100 fc. The light on the storage-side of my garage is still a respectable 60 fc.–more than enough light for non-woodworking chores.
Step 4: Call in a pro
Adding breakers is best left to a licensed electrician, but you can do some of the work yourself and save money.
To prepare my shop, I cleared out the work zone and mapped out the exact arrangement of the fixtures with string and cardboard templates. The electrician installed and wired a shop’s worth of fixtures in two days.
Step 5: Buy bulbs and test your setup
Because color is influenced by the colors of your shop, the types of woods you use, and even your age, Kelvin color preferences vary from one woodworker to the next.
To discover what works for you, you’ll need to buy bulbs (I suggest a pair) in a variety of different color temperatures. If you’re interested in a warm look, try lower-K bulbs in the 2,800-4,100K range. If you’re looking for clarity, start with 4,100K bulb and work your way up. Mark the bulbs to avoid accidental mix-ups, and then install them into a single fixture and check the light. When you find a comfortable color temperature, buy a case of the bulbs, and install them in all the fixtures. At this point, you can test-run your shop. A lighting meter (sidebar, right), can help you find the dark spots.
All fixtures are not created equal. Here’s what to look for to get the most from your fluorescent tubes:
Reflectors - Reflector-less fixtures that rely on the ceiling to reflect the light are less efficient than those with reflectors, and ineffective in shops with exposed joists. Reflector-clad fixtures cost more, but help the lamp deliver light were you want it.
Lenses - A lens spreads out light and protects bulbs from dust (dust build up can reduce light output by 10% each year). Besides reducing cleaning chores, a lens protects the bulbs from accidental collision with a long board or bar clamp.
Ballasts -The ballast supplies a high initial voltage to light the lamp and prevent flickering. Today, electronic ballasts are standard, but if your fixtures are more than three years old, you might consider an upgrade. Magnetic ballasts cause lights to buzz and flicker, and are slow to start in cold weather. (In some instances, magnetic ballasts can create a strobe-effect that can make a rotating saw blade appear stationary.)
Fixture Placement Guideline
1. Measure the distance from the fixture to your primary work surface (A).
2. Position the first row of fixtures (B) no more than 3⁄4 (A). (In the drawing, distance [B] is only 1⁄3 [A].)
3. Position the next row of fixtures (C) no more than 1.5 times the distance of (A).
Meters: Lighting by the Numbers
By gauging the quantity and quality of existing light, a light meter can help you determine if it’s time to replace a few bulbs (many dim as they age), install additional fixtures, or add a few task lights.
Battery-powered digital meters are the easiest to use: simply set the light-sensitive cell in the desired location and check the readout. Because the readout changes as quickly as you move the sensor, look for a meter that offers a means of holding a reading.
If you own a tablet or smartphone, you can download an app that can turn your device’s camera into a light meter. Free apps are available, but I purchased the LuxMeterPro’s “advanced” for $2.99. In addition to a basic meter, this version includes a color spectrum analyzer that can identify the K-temperature of fluorescent lights.
Task Lighting – Bulb Basics
Since 100W incandescents were phased out in 2012 to make room for energy-efficient alternatives, buying a bulb isn’t as easy as it used to be. If you’re nearing the end of your stockpile, don’t stress out; there are several suitable substitutes to choose from.
Updating the bulbs in your home can shave hundreds from your annual utility bill, but if you only spend a few hours a week in your shop, it will take years to recoup the cost of super-efficient replacements. For shop satisfaction, focus your attention on light intensity (lumens) and color temperature (K), and then on longevity and power consumption.
Incandescent bulbs work by heating a tungsten filament to produce warm, but woefully inefficient light. (Only 5-10% of the electricity becomes light, the rest of the energy consumed becomes heat). These bulbs are inexpensive, but short-lived. Incandescents also get darker as they burn, causing an old bulb to produce only 82% of the light it did when new. Despite government restrictions, if you want to stick with incandescents (and keep your electric meter spinning), you can still find 100W and 150W “service bulbs” at most hardware and home stores.
Rough Service, $4.16 1,230lm, 2,700K, 100W 900 hours
Utility, $2.58 2,740lm, 2,850K, 150W, 750 hours
Flood, $7.98 510lm, 2,650K, 65W 2,000 hours
Compact Fluorescent (CFL)
First-generation CFLs started off on the wrong foot. They were slow to start, they cast a ghastly blue light, and their oversized coils stuck out of most fixtures. Today, the coils on most are compact and/or concealed, and the bulbs have been tailored to produce light that’s nearly indistinguishable from incandescents. Most importantly, CFL prices have plummeted, offering an easy way to save money. However, CFLs aren’t perfect. The larger-lumen bulbs still may not fit some older fixtures. Also, a CFL’s lifespan can be shortened by vibration.
Flood, $8.98 750lm, 2,700K, 15W 10,000 hours
Close cousins to incandescents, halogens also employ a tungsten filament, but because they are more efficient, they meet government regulations. In some cases, a halogen bulb’s lifespan isn’t much longer than an incandescent, but it doesn’t darken with age; old bulbs produce 94% as much light as did when new. In comparison, with CFL’s and LED’s, halogens cost less up-front and throw more lumens, but cost more to operate. A halogen bulb’s real Achilles’ heel is that it runs much hotter than a CFL or LED. For that reason, it’s important to keep bulbs away from flammables and flesh, and to make sure that the bulb size does not exceed the fixture’s wattage capacity.
Clear, $3.27 1,490lx, 3,000K, 72W 1,000 hours
Light-Emitting Diodes (LEDs)
The newest bulbs on the block, LEDs produce little heat, run on few watts, withstand vibration and shock, and last for decades. LEDs are suitable for many applications, provided that you pay close attention to the label. First check the lumens. Many “replacement” LEDs do not provide as many lumens as the bulbs they’re replacing. Next, check the color temperature. In order to boost perceived output, many lower-lumen LEDs produce cold, high-K light.
Frosted, $20 500lm, 5,000K, 5W 30,000 hours
You must be logged in to write a comment. Log In