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  Another kitchen-table moneysaving project that no magazine on Earth would pay for
A SADS Light Box in 2 Hours for under $50
If I can build it, you can build it...and probably with a lot less grief!
Last updated 08/11
"Three hundred bucks? Are you kidding me?"

Don't look like much, does it? It ain't, but I'd put it up against just about any $300 "light therapy" box for effectiveness. It's simple, safe, and best of all, dirt cheap to build. Click here to load a detailed 1400x1400 version of this photo (150kb), click here for a different angle.

SADS - Seasonal Affective Disorder Syndrome - has been in the news for nearly 25 years now. The value of light therapy for SADS and jet lag is so universally accepted that some trans-Pacific airlines actually install small full-spectrum lamps in their seats to shine on passengers' calves periodically during the flight. Yet light-therapy boxes are still a specialty item sold at specialty-item prices. Homemade options have always been provided, but until relatively recently they've been problematic. Designs using the classic four-foot-long fluorescent tube have always been the least expensive option for sufferers on a budget, especially since full-spectrum tubes fell below $10 each, but any light box capable of holding enough of them will inevitably be so large that it leaves the owner with the same storage and setup hassles as the home treadmill. Designs using incandescent "grow" lamps have been recommended over fluorescent models for twenty years, but they require expensive electrical components, equally-expensive high-output bulbs, and any corners cut in construction could leave you with a nasty fire hazard. Surely there must be a better option than a $200-500 purpose-built light-therapy box!

SADS has been a familiar if unwelcome guest in my family for at least three generations. But we typically enjoy complaining about our minor ailments more than actually doing something about them, because...well...you can buy a lot of comfort and consolation for the cost of proper therapeutic aids. Let's see...$300 buys 75 bags of Doritos, nine cases of beer, a dozen fifths of gin, two days in Cancun...you get the idea. It's only been within the last two years that a truly affordable and usable homebrew light-therapy option has become possible.

The design I'm presenting here uses an interlocking-top 56l/15-gallon-type plastic tote, a small slab of plywood, a spare extension cord or a couple of discarded appliance cords, a dozen phenolic/hard-plastic light fixtures and a dozen 26w screw-in fluorescent lamps. Three years ago (2008), these totes were hard to find under $25. Today, you can get them for as little as $8. Phenolic fixtures have been about a dollar apiece for many years, but the 26w lamps were so scarce just three years ago that they typically cost upward of $15 each; today you can buy boxes of four at any big-box for under $10. If you had built this project in 2008, it would have cost you nearly $200; today, it can be built for under $50. And it's not likely to ever again be this cheap to build.

So how well does it work?

Light output: 17,500 full-spectrum lumens. My personal light box uses eleven 26w spiral fluorescents, comparable to the output of six to eight 40w long fluorescent tubes, from an area less than half of what would be required for eight tubes installed side-by-side. I use nine full-spectrum "sunlight-matched" lamps, and two "warm" lamps in the center. The most common complaint about homebuilt light boxes is that they don't spectrum-match with the sun to a sufficient degree; they tend to be deficient at the red end of the spectrum. Using the two "warm" lamps in the center of the box boosts the total output from the red end to compensate, and as the photo above shows so clearly, the brilliance of the box when it's plugged in is really something to behold...I've seen $500 light boxes which don't come close to this level of brilliance. It definitely works for me. I've tried a purpose-built light-therapy box for a period of several days just to see if I'd benefit from them, and my homebuilt light box at least matches, if not exceeds, the results I got from the purpose-built unit.

Of course, your mileage may vary. Different people have different needs, and you may need the extra benefit of boosted spectral ranges in made-to-measure light boxes. But for what this costs to build, it might still be worth trying. Even if you don't use it for SADS, you can set it on a roof for instant party floodlighting, on a porch for patio parties, or use it as a photographic lamp to optimize your eBay photos.

A close examination of the criticisms leveled at homemade light boxes raises some interesting questions. The key to light therapy is to get sufficient light onto certain receptors in the skin to stimulate the production of Vitamin D and melatonin (the skin-pigment substance is melanin, not melatonin). There also seems to be evidence that the eyes need sunlight exposure as well; closing your eyes and facing the sun for several minutes apparently allows all the light necessary to reach the back of the eye to produce the desired metabolic changes.


The light box is the only illumination in the room other than the CRT TV and the LCD PC monitors, both shown here for perspective. Look at the brilliance of the carpet around the box...that's strictly from light reflected from walls and ceiling!.

Critics argue that full-spectrum fluorescents can't produce a wave band that sufficiently matches the Sun to produce genuine therapeutic results. But just how close do you have to be? The truth is that there's no definitive answer at this time. I find it impossible to believe that only a costly specialty tube can produce the spectrum band needed for proper SADS therapy, although these devices might be the only things that work for a small percentage of individuals with particularly serious SAD syndromes. Full-spectrum fluorescents are more than sufficient to grow indoor plants as healthy as their outdoor counterparts, and the use of full-spectrum fluorescents in offices where people work multiple shifts has been blamed for causing insomnia and metabolic upsets in evening and night workers, precisely what you'd expect from exposure to sunlight at the wrong hours, and the exact same effect that SADS sufferers typically hope to achieve from light therapy.

So while I acknowledge the benefits of specialty light-therapy tubes for certain individuals with extreme needs and enough money to afford specialty light therapy devices, I can't find any real justification for criticizing full-spectrum spiral lamps as "ineffective".

Heat output: surprisingly manageable, but never plug it in while covered! I was also concerned about heat output. You can't build a homemade box like this with incandescent bulbs; the heat would result in a serious safety concern. Truth to tell, if I ever plugged this in with the top covered, it would be reduced to a puddle of melted plastic in less than an hour. But as long as it's kept open, and the interior of the box is fully covered with reflective white sheeting, the heat output from this rather frightening-looking cluster of spiral lamps should never be a safety concern.

The design I'm presenting here does not include a safety shut-off switch of the type that protects household heaters from starting fires if they're knocked over. This device shouldn't need safety shut-off switching. In normal use, you'll plug it in, sit within a few feet of it for up to half an hour, and unplug it again until the next day. Cut-off switching should only be needed if the device will be abandoned for significant periods of time while it's in use.

Essentially, this device is not as safe as modern consumer-grade household heaters. But it's certainly as safe as any heater made up to about 1990. Just take the same precautions with this device around young children that you'd take with a heater or a toaster.

What you need to build this project...and what it costs

This isn't the simplest project in the world to build, but it doesn't require a lot of tool smarts, or a lot of tools. More than anything else, it requires patience, which I know is asking a lot from a SADS sufferer. Here's the rundown:

Tools needed:

Materials needed:

Putting it together

Follow these instructions in order, and you're likely to save yourself a lot of the hassles and work-arounds that I had to endure when building my box. This should go together in less than two hours; mine took nearly four to build. Here are the steps involved:

  1. Cut the plywood/particleboard base to size and attach to the tote
  2. Template the base of the tote for the light fixtures
  3. Create a dozen connector cables for the fixtures
  4. Connect the fixtures together
  5. Drill screw holes for attaching the fixtures
  6. Line the inside of the tote with reflective sheeting
  7. Attach the power cable and test the circuit
  8. Attach the fixtures to the base of the tote
  9. Add strain relief to the power cable
  10. Install the fluorescent lamps
  11. Optional: Attach a hinged "stand" to the plywood base
  12. Heat-test the finished product for safety

Step 1: Attaching the plywood/particleboard base

1. Cut the base board to size.
First, you need a piece of plywood or particleboard at least 3/4" (2cm) thick. You'll be mounting the light fixtures to the bottom of the tote, so you'll need something thick enough that the screws bond the fixtures tightly, but don't allow screwpoints to peek through the bottom of the board. You don't have to be exact with your cuts...it's okay if the board extends out a half-inch or so, or is an inch or so shorter than the tote itself. Don't use corkboard, wallboard/Gyproc, or anything else that can be cut with a knife or broken with your bare hands. Try to use a single piece of wood for the entire base; two or three lengths of 1x6 or 1x8 could do in a pinch, but it's not the ideal choice. If you're guessing while cutting, you'll have the easiest time if your base board is too small rather than too large. Tape off the edges with vinyl or Gorilla tape at this point if you like; see the photo at the bottom of this page to see how I trimmed my own box.

2. If needed, grind off any protruding "feet" on the bottom of the tote.
Most totes of this type have flat or slightly ribbed bottoms. Some have molded "feet" on the corners that raise the bottom of the tote up to half an inch. If your tote has feet like this, you'll need to file, cut or grind them off before attaching the base board. The base needs to fit as tightly to the bottom of the tote as possible, but gaps up to 1/8" (5mm) shouldn't pose a serious problem.

2. Tape the base board firmly to the bottom of the tote.
Using your vinyl or Gorilla tape, attach the board to the bottom of the tote along the edges. Attach it tightly. Once it has been taped to the tote, it shouldn't move at all when you try to shift it.

That's all you need to do. You'll remove this tape once the project is done; the screws that hold down the fixtures will also hold the base board to the bottom of the tote. The tape is only needed during the assembly stage of the project, but it must be strong tape and it must hold the base board as immobile as possible to insure holes are drilled as accurately as possible.

Step 2: Templating the base of the tote

Make sure you finish this step before lining the tote with reflective plastic.

1. Arrange the fixtures on the inside bottom of the tote.
As the snapshot at right shows, I got very lucky with my tote; it was perfectly sized to allow 11 fixtures in a honeycomb arrangement. You might not get as neat a fit, but you should be able to fit no fewer than 11 fixtures onto the base in some pattern. It doesn't have to be a perfect pattern, and spacing doesn't really matter.

2. Mark drill points for your first fixture.
Each of the oval openings on either side of the bulb receptacle will have a narrow end, wide enough only for the threaded part of the screw, and a wide end, wide enough to fit the whole head of the screw through. Your marker will probably only allow you to mark through the large end, which is fine. You don't have to mark through the narrow end of the opening, which is where you'll actually screw down the fixture, but you do need to make sure that you mark as close to dead center of the hole as possible, and mark the two holes exactly opposite one another. So if you can use the small holes, that's fine...just make sure that's all you use. If you use the large holes, that's fine too...just don't mark one of a fixture's drill points through the large end and one through the small end or you'll have problems later. It shouldn't matter how you align your drill points, but if you mark them all along the same alignment (e.g. top-to-bottom, left-to-right, or a diagonal line), it might simplify the final installation later by standardizing the distances between the holes through which the cabling must travel.

3. Firmly tape down the first fixture.
I recommend using masking tape; it's quick and easy to peel later.

4a: experienced handymen: Mark drill points for your remaining fixtures.
Simply mark drill holes for each fixture, and tape down each succeeding fixture as the holes are marked, until drill points for all fixtures have been marked.

4b: novice handymen only: If you're not very handy, here's what might happen. You might find when it comes time to screw down the fixtures that your fixtures aren't properly spaced, and need to be filed down in order to fit onto the holes you drilled. This could, add as much as an hour to your total assembly time.

Here's how to avoid that particular problem. Once you've marked your first fixture and taped it down, set the second fixture tight to the first, and then move it 1/16" away before marking drill points. This should give you enough margin for error that you never have to account later for a too-tight arrangement of fixtures. Firmly tape down each succeeding fixture before marking the drill points, and allow a 1/16" gap between any two fixtures. You should still be able to fit all of your fixtures onto the base of your tote; it's highly unlikely that you won't have some leftover space on the bottom of the tote.

5. Mark a drill point on the tote for the power cord hole.
I recommend feeding the power cord through one of the short sides near a bottom corner, but you can put this hole anywhere provided that it doesn't risk running electrical cord near a warm lamp surface where melting could occur.

Step 3: Creating connector cables

If you're starting with leftover extension cord, you can start anywhere. But if you're using a complete extension cord, start by snipping off the receptacle end of the cord, leaving the plug end for possible use later as the power cord, providing it has at least 6 feet of cable left on the plug end.

Always use white or cream-colored electrical cable for connector cables. Any darker shade will absorb heat from the lamps. A certain amount of heat is inevitable, but everything you can do to keep heat inside the box as low as possible will extend the useful life of your light box. You also need to make sure that the insulation has something of a rubbery feel to it; the more plastic-like insulation used on cheaper Christmas light extensions could be less resistant to heat. Extension cable sold for indoor Christmas-light use should not be used for this project. Ordinary white extension cord should have all the heat resistance and power handling you'll need for up to fifteen 26W lamps, which is the most that I would recommend for a single light box.

1. Mark one of the two conductors on the cord with a black line using your marker.
This isn't strictly necessary, but it's a useful habit to acquire. This project doesn't require that all cables be

2. Cut eight 10" (25cm) lengths of extension or appliance cord, and three 11" lengths.
You might find that you need a couple of slightly-longer cords as you align the connected fixtures in the tote for the final screwing-down. If you have any concerns about cord length, cut only one or two cords at a time to allow for any installation problems later..

2. Split the cable at both ends.
Electrical cable is often referred to as "zip cord", partly because once you start a split between the two conductors, it tears apart with almost no effort. Starting that split can be a problem though; the quickest way to do it is with a pair of wire cutters as shown at right. You'll need at least two inches of split at each end to allow the insulation-stripped leads to reach their separate terminal screws.

3. Strip 1/2" (12mm) to 3/4" (18mm) of insulation from each of the four "leads" on the connector cables.
 If you don't have a crimper, which is the tool designed for this job, you can do as good a job with a box cutter blade in almost as short a time. Simply roll the insulation over the sharp edge of a box cutter blade, and the insulation should easily pull away from the wire without cutting more than a few strands of wire. You'll need to do this four times for each connector cable, so you'll probably get quite good at this by the time you're done.

4. Twist the bare wire and bend the twisted wire into a "u" shape
...as shown in the photo above left. Always twist the wire in the same direction (usually clockwise), and the u-shape should also be bent in a clockwise direction. Don't try to screw the wire onto the metal fixture terminals until you've twisted it together or stray strands of wire will stick out. This is an extremely safe project, so a bit of stray wire won't hurt anything, but it's bad practice and a dangerous habit to get into.

Step 4: Connecting the fixtures in a chain

The goal in this step is to create a string of fixtures, all properly connected to one another, which is well-enough assembled that you can pick the entire assembly up by one fixture and carry it casually around the room without any of the wires coming loose from the screw terminals. It's not that hard to do; it just takes time.

Before you start, create a "convention". You'll notice that the receptacles have two metal "terminal strips", each with a pair of screw-down "terminals". Black-marked wires should all go to the same color of terminal. A mnemonic is useful for helping you stay consistent; I recommend a memory-aid phrase such as "black gold" or "silvery-white". Never connect both wires of a length of cable to the same terminal on the same receptacle. This will create a short-circuit. It shouldn't cause any harm, but it will overload your electrical outlet and cause a fuse or breaker to blow, which is annoying. A short circuit of this type should never pose a safety hazard since it will always overload your household electrical circuits causing an instant blown fuse or breaker.

It won't harm anything to mix up the terminals, but it does affect the "phase" of the fluorescent lamp, which is meaningless for our purposes. Some people prefer to have half of their lamps in one phase, half in the other, meaning that half of the black-marked wires would be attached to silver terminals, the other half to the gold ones. Safe electrical practice involves always keeping things in the same phase, so you may want to keep same-color wires on same-color terminals for all fixtures just to help yourself get into a good habit.

Here are the steps to creating your fixture network:

1. Prepare the receptacle for the cable, OBSERVING APPROPRIATE SAFETY PRECAUTIONS.
You'll notice that these receptacles are designed with flush bases. You'll have to create a channel of some sort to feed the cable from beneath the receptacle. I create mine by breaking off bits of material from the edge of the screw hole as shown here. This needs to be done gradually, breaking off small bits of plastic at a time and grabbing no more than 1/8" of plastic at once, or the entire receptacle will split. (Hence the shopping list that calls for an extra receptacle.) You can also file out a couple of small tunnels from the outer rim which allow the cable to feed out the bottom; I prefer to have it come out the screw holes. Even filing out tunnels can cause receptacles to split, as I discovered several years ago when using these to build a light bar for eBay photos.
Always perform this part of the job outdoors while standing upwind of the receptacle.
If these receptacles are made from melamine, you need to remember what melamine is made from: resin and asbestos. The asbestos is entirely safe when locked into the melamine, but when ground down using a file, or shattered with a pair of needlenose pliers, small amounts of asbestos could be released. The risk really is very minimal, since the asbestos is locked into the resin in a vacuum, meaning it's very difficult to ever again separate from the resin, but if you can avoid inhaling a few hundred asbestos fibers, why wouldn't you?

1b: Feed one end of a connector cable through the prepared screwhole.
(Not necessary if you're feeding the cables through tunnels in the rim of the receptacle.)

2. Attach one lead to one receptacle strip, the second lead to the other strip.
Hook the U-shaped wire around the screw, always in the direction shown in this photo, and tighten down the screw. Don't tighten the screws down with any more force than you might use on a mildly-stuck jar lid, or you could strip the terminal thread or even snap the receptacle. You just need to make sure that the bare copper wire is snugly fastened. Don't worry about a few stray strands of copper, or a bit of extra wire sticking out. You'd need to have bare strands of an inch or longer before they pose any risk of causing a short-circuit. Try to attach all black-marked leads to one color of screw terminal; the non-marked leads to the other color. You don't have to get this right, but it's good practice to get into.

3. Feed a second cable through the other receptacle hole and attach it to the other terminals.
The snapshot at right shows a finished receptacle with the leads attacked properly...both black leads on the gold screws, both white leads on the silver screws.

Once you've attached a second connector cable to your first receptacle, and connected the second receptacle to that cable, you'll have a pretty good idea of how it's done, and why I've recommended certain steps or precautions.

4. Attach only one set of leads to the first and last receptacle in the chain.
The second set of leads attached to the first receptacle will be the leads for the power cable. The last receptacle only needs the one set of leads.

5. Test the chain of receptacles.
No leads should fall off if you dangle the chain by one of the receptacles. Lay the chain inside the box and snake the chain around inside the box until you can line the screw holes up over the guide mark dots you made earlier for every receptacle that you've wired up. You should be able to "dead-center" every dot, every fixture should lay flat on the bottom of the case, and you shouldn't have any excessively-tight connector cables. This is where you find out whether your guide holes were marked properly, and whether you need any longer

DO NOT attach the power cable yet.

Handyman's option 1: If you have a few inches of zip cord left on the receptacle end of your "donor" extension, or a spare receptacle stub from an old extension cord, you can optionally wire this to the last receptacle for use as an extension or utility outlet for the light box. This utility outlet should be fed to the outside of the case, however; if left inside, you run the risk - low but still real - of melting the power cable of any device you plug into it. If the receptacle stub is fed through to the outside of the case, you run no such risk.

Handyman's option 2: If you have an old 120v toggle switch of the type used on old radios and lamps, you might want to bolt it onto the outside of the case and use it as a power switch for the light box, remembering that the project as it's described here has no power switch and remains on for as long as it's plugged in.

Handyman's warning: Do not use an inline power switch for this device unless it comes from a high-power device such as a heater! Most of the inline rotary or rocker switches used on extension cords are designed for Christmas lights and table lamps. This device will draw nearly 300W when in use, and this exceeds the maximum safe wattage for nearly all inline switches used on household extension cords. Inline heater switches can handle high current draws, and should be entirely safe for this application.

Step 5: Drilling the screw holes

You can use any household drill for this job, but I recommend a lower-speed battery-powered drill because it offers more control than high-speed plug-in drills.

1. Select the appropriate drill bit. Hold one of the receptacle screws beside the drill bit and hold the pair up to the light. The right-sized drill bit should be the same width as, or just slightly wider than, the shaft of the screw not including the thread. If you select too wide a bit, the screws won't fit tightly and you'll need to glue them into place. If you select too narrow a bit, you'll need to grease the screws to get them through the case and into the wood.

2. Drill starter holes at all guide points using a 1/16" drill bit. It is extremely important to "dead-center" your drill holes as perfectly as possible, so take the extra time to drill shallow (1/4"-1/2" deep) starter holes using a small drill bit that can be easily guided and kept to the dead center of your drill point marks. Do not overdrill these holes. It won't harm the finished product if you do drill your starter holes too deep, but it looks unprofessional and the holes will collect dirt.

2. Prepare the next drill bit with a depth guide. Once you've selected the right size of drill bit, you need to make sure that you can't drill too deep a hole. Handymen can use the "marker ring" method shown top left, but the "novice" guide will probably be a better choice. The marker ring only shows you how deeply to drill. Wrapping an eighth-inch thick layer of electrical tape around the bit will actually stop the bit from drilling further once it reaches the desired depth. Set your depth guide, however you create it, to no more than 3/4", just enough to get through the bottom of the tote and halfway through the base board, and not deep enough to leave holes in the bottom of the base board.

4. Drill the holes for the first two receptacles. Set the first two receptacles into the tote, (starting in the corner where the power cable will be installed, of course, and not in the middle of the tote) and use the screws provided with the receptacles to hold them down. Just turn the screws hand-tight to get a sense of how everything fits. The two receptacles should fit neatly, not forcing the screws to sit at an angle, and the cabling should be long enough to allow everything to fit properly.

5. Drill and test each additional receptacle until the entire chain is installed "hand-tight". Be sure to check your depth guide after every few holes to see that the ink hasn't worn away or the tape hasn't slipped. Heat buildup in the drill bit can cause a plastic-tape depth guide to slide up the bit when you drill to depth and this could cause you to over-drill if you don't notice the slippage.

If a connector cable is too short, replace it with one of the longer spare cables made earlier.
If two receptacles "crowd" each other", you will need to re-mark and re-drill the screw holes for that receptacle. Do not try to wedge things in too tightly unless you're sure you can do this and make the results last; rotate the receptacle at least a half-inch before re-marking to avoid facing this problem.

6. Remove the receptacles and carefully clean away stray shards of plastic from the drill holes on the inside of the tote. You don't have to be a stickler here, but do keep this in mind. You are not going to punch holes in the plastic that lines the inside of the tote. Instead, you will use your fingers to "feel" for the drill holes through the plastic, and tighten the screws directly into the plastic lining without cutting it. A little bit of leftover plastic around the edge of a screw hole will make it that much easier to find your screw holes when it comes time to assemble the box.

7. Drill the power cable hole. This hole should be drilled about a half-inch from the corner of the case where the first receptacle in the chain will be installed, and no more than an inch from the bottom of the tote. Drill the smallest hole that will easily allow the power cable to pass through it.

8. Smooth the inside of the power cable hole. You can do this by shaving away bits of plastic with your box cutter. This hole should have a smooth inner surface and no sharp edges that can catch and possibly split the insulation of the power cord. If you're reasonably careful about not putting strain on the power cable when the box is in use, then punctures and splits at the point where the cable meets the tote should never be an issue, but it's a good idea in any case.

Step 6: Installing the reflective lining

This should be the most straightforward step in the process. Simply cut oversized lengths of reflective plastic, fit them into the case, and trim them to size. Use the double-adhesive foam mounting tape, mostly at the corners where it's most needed, to hold the reflective sheeting down, and you're done. If you can find 2" white vinyl tape locally, it makes excellent patching tape for any areas that you didn't manage to cover properly. You don't need - and shouldn't use - mounting tape for the bottom of the case, only the sides. Do not try to line the flaps with the same length of reflective sheeting as the inside of the case; use separate pieces of plastic for each flap...it'll make life a lot easier once you begin to actually use your light box.

Before finishing this step, run your fingers along the bottom of the case and either make pin-punctures or Sharpie marks on the reflective plastic wherever you feel a drill hole. It will significantly speed up the final mounting of the receptacles.

Step 7: Attaching the power cable and testing the circuit

When selecting a power cable, be sure to get the length and capacity right or it could cost you a bit more work to replace than you might want. The cable should be at least six feet (2m) in length, preferably 10-12' (3-4m), and should be "light duty" or better, meaning that it can handle 300W of power on a continuous basis. "Seasonal" cables used for Christmas lighting are usually not sufficient, and could pose a fire hazard. Older cables should be avoided if there is any corrosion visible on the plug spades or the bare wire after you've cut away the insulation. Three-prong cable isn't necessary, and should not be used by inexperienced handymen.

1. Cut an opening in the reflective sheeting for the power cable. The only area of the reflective sheeting that you will have to cut is the point at which the sheeting crosses the hole for the power cable. Cut a circle or an "X" large enough to allow the cable to pass through, and you're done.

2. Feed the power cable, cut end first, through the hole, with the plug end to the outside of the case.

3. Split and strip the ends of the power cable exactly the same way as you stripped them to install the connector-length cables.

3b. If you're using ordinary extension-cord cable instead of the heavy-duty stuff I used, you can add your strain relief now instead of later. Simply tie a simple knot in the cable, and squeeze the knot tight leaving no more than 5"-6" of cable between the knot and the bare wire ends. It's not considered good practice to do this, since it puts stress on the wire and insulation where it's tied in a knot, but this is all that most cheaper imported appliances use for strain relief, and it's all that you should need.

4. Attach the bare leads of the power cable to the remaining two terminals on the first receptacle. It doesn't matter which lead goes to which terminal, but correct practice involves connecting the lead attached to the wider spade on the power plug to the connector strip used for the black-marked leads. If you're using a three-lead power cable (which you should not do unless you know your electics), cut the unused third lead as close to the cut in the outer insulation as possible, and wrap the exposed end in a layer or two of electrician's tape.

5. Test your work. At this point, the only exposed metal in the case should be the contacts in the receptacles that power the lamps, so that's the only thing that can shock you. Install any lamp - preferably a low-wattage lightbulb - into the closest receptacle to the power cord and plug the device in. The bulb should light. Check each additional receptacle up to the end of the chain to make sure they're all working. When you get to the last receptacle, be a little bit violent with the box. Shake the receptacles (being careful not to touch a metal contact) and bang the box on a table to see if this causes an interruption to the bulb. Interruptions won't be as easy to spot with fluorescent lamps, which is why an ordinary lightbulb is best for this testing.

Always unplug the device before making any adjustments or repairs.

Step 8: Final installation of the receptacles

Now that you know the circuit is working, simply tighten the screws, which should already installed "hand-tight" on the receptacles.

Once the screws are firmly in place, you no longer need the tape that's been holding the base board in place, so you can remove it. With all those screws holding it to the base, it'll take a crowbar to separate it from the tote now.

If you plan to store this device in a closet with wood floors, you may wish to nail on two-inch squares of shag carpet or screw a set of rubber feet onto the base to remove any risk of scratching. My home is entirely carpeted or tiled, so I haven't bothered to add feet to my light box.

Step 9: Add strain relief to the power cable

If you didn't take care of this earlier by tying a knot in the power cable where it enters the case, you'll need to do this now. You need some way of making sure that when you accidentally tug a little too hard on the power cord that it doesn't pull the wires off of the first receptacle where it's attached.

Consumer-grade products typically use a custom-fit "collar" which squeezes the cable at the point where it enters the device. You don't have that luxury.

If you happen to have 3" cable ties, they work quite well. Simply wrap a cable tie around the cable on the inside of the case, and this should make the cable too thick to fit through your guide hole. If this doesn't work, try wrapping several windings of electrical tape around the cable on the inside of the case and then using the cable ties. These ties are very tough - typically nylon - but they do break, so never settle for just one; two or three will add extra insurance against accidentally pulling the power cable out of the case.

Wrapping tape around the cable until it's too tight to fit through the guide hole is the usual amateur method, but it's not the best. A better way is to wrap tape around the cable leaving a cone-shaped series of wrappings, then feeding the cable into the hole until it wedges tightly where the wrappings won't allow it to go further. This type of strain relief is almost as effective as a commercial "collar"-type strain-reliever.

Step 10: Installing fluorescent lamps

Simple enough...you can mix and match warm/full-spectrum lamps, but I've found it best to use the "warm" lamps in the center of the box because they produce the most heat and should be kept farthest away from any surface that might melt. "Cool" lamps don't contain a full sunlight spectrum and aren't suited to use in this type of application.

Step 11: Attaching a stand

I don't use a stand; I simply lean my box against a hassock to the angle that I need, or I use one of the flaps as a prop. But if you do need a stand, the easiest way to create one is as follows:

  1. Cut a length of board the same length as the base board on the light box. It doesn't need to be more than a couple of inches wide, but it shouldn't be wider than the base board itself.
  2. Attach this board to the base board along the short edge using an ordinary kitchen cabinet hinge.
  3. Using push pins or thumbtacks, attach a short length of chain (a dollar-store choke chain will be more than sufficient) halfway down the thin sides of the two hinged boards so that the box can stand in the same way as a sidewalk sandwich board.
  4. Adjust the chain to the desired length, and staple or nail it to the two boards, then remove the push pins or thumbtacks
    ...or...
    Nail or staple down one end of the chain, and pound a one-inch nail about 3/4" into the side of the other board for use as a hook. This will allow you to adjust the length of the chain and set the hinge angle wherever you need it.

Step 12: Heat-testing the finished product

Is this device ready to go, or will it need to be used with a fan to minimize heat buildup? Time to heat-test it. Naturally you should never, ever plug this device in with the flaps closed, or allow it to sit face-down on a floor. If these are real risks, then you'll either need to install some sort of "tip switch" such as those found in modern space heaters, or abandon the idea as unsafe for your needs.

Since you'll probably only use this in cooler weather, it shouldn't matter when you do your testing. But it's important to plug it in and leave it running for at least a half-hour in a room with minimal air circulation to get a proper reading on how it accumulates heat. Your biggest concern will be the temperature of the top edge of the box, so to create the maximum possible heat, set it on the floor on a short side, which allows the most heat to rise to the top of the box.

Check it after a few minutes to see how hot the top edge of the box gets. If anything is showing signs of melting, you've obviously got a heat problem. My box can run for a full half-hour without the top edge becoming too hot to touch. But if your light box does accumulate heat (certain makes of fluorescent bulbs emit more heat than others), then you'll need to use a fan with your box.

Option 1: Install an old computer fan.
If the problem isn't severe, try installing an old computer fan in one corner of the box. These fans should push all the air needed to keep the box from overheating, and they'll provide all the ventilation needed using only a spare 5VDC USB charger adapter, or a discarded 6VDC adapter. Just snip the plugs off of the adapter and the fan, twist the wires together and plug it in...if you wired it wrong, it will either blow backwards or not at all, and the problem can be fixed by reversing the connections between the fan and the adapter. Since most of these fans are designed to be run at 12VDC, running them at 6VDC is no problem at all, and actually results in a much quieter and far less "breezy" operation.

Option 2: Run a fan on the box whenever it's in use.
If the heat problem is fairly serious, don't give up just yet. Chances are excellent that it will run cool and clean for hours on end if you simply blow a small table fan into the box while it's running. It's a bit of a hassle, sure, but if the alternative is a purpose-built light-therapy box that seriously taxes your budget, you'll probably find it to be a tolerable inconvenience

Option 3: Abandon the project.
If a table fan won't keep your light box cool enough to prevent anything from melting during normal use, then your light box is too dangerous for home use and should be abandoned at least for the time being. It's possible that you've used older 26W lamps which emit too much heat; newer models use much more efficient voltage converters and run much cooler than the high-output fluorescent "bulbs" of 2005 or earlier. You might also want to check your construction. Did you use a white enough (or shiny enough) reflective sheeting? Are there too many dark surfaces inside your box that should be painted or taped in white? Are there exposed dark edges which might be accumulating heat?

It's not likely that you'll have to completely abandon your project except in the most extreme circumstances. .

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