LED Floodlight Build

Purpose: Using LED 'Floodlight' style fixtures, build a multiple light fixture for ceiling mount above plant bench. My goal is to improve appearance of the build over my usual spaghetti cluster of wires, and also to make this a unit design that can be mostly completed at bench level instead of with arms over head. In this build I will mix 'bright white' and 'warm white' fixtures, hopefully providing both the blue and red ends of the light spectrum necessary for proper orchid growth and bloom.

Background: I've been using these lights for a while, and I like them for growing plants. Yes, I know I could get better efficiency and probably better growing spectra by purchasing 'grow-light' style fixtures or designing my own (that is another page, coming soon). I do have grow lights, and use them in certain circumstances. Because I grow ornamental plants (orchids, mostly), not medicinal plants, I like 'white ' light for a number of reasons. Not the least of which is that I can actually see the flowers.

The lights I am using are inexpensive, waterproof (water resistant, more accurately), and relatively durable. They are designed for outdoor use. They are more efficient in terms of lumens per watt than fluorescents, and less breakable (ever gotten cold water on a fluorescent tube? It isn't pretty). There are negatives. One, the light is more visually appealing than tuned for plant growth. I can live with that. Two, attention to construction detail and quality of parts (most particularly the LED Drivers) in these Chinese made units is hit or miss. I've had very good luck with the 30W units, but poor luck with 50W units of the same type. It is relatively easy to replace the drivers in these units with higher quality components if they do fail, although this is an unwelcome additional expense.

So, with all that formality out of the way, the actual build, with pictures. I thought about making this into a video, but if you've ever seen one of my videos you'll appreciate the text version...

The build:

First, the lights. 30W LED floodlights, ordered from a chinese wholesaler. I received cool white and warm white fixtures in the same package, of course they were not labeled as such. After a little testing, it seems that the green boxes are warm white, blue are cool. Yes, my workbench (also my potting bench) is a disaster, get used to it, you'll see it a lot.

Test your lights before you do anything else. I've done this a lot of times, and my solution is to scavenge a cord with a plug from another appliance, and solder on alligator clips to the end. I just attach the clips to the wires coming out of the fixture and plug it in! Either works or it doesn't - so far I haven't found a single unit that doesn't work the first time, but it still doesn't hurt to check. In these Chinese wired units, brown wire = black (hot), blue wire = white (common/neutral).

To provide rigidity to the fixture and to provide a way to mask wiring clutter, I have chosen to use a six foot piece of material originally designed for use as a shelving support. Since my benches are 8' long, I would have preferred a slightly longer piece of steel, but I'll make it work for that price. You can find this in the closet and closet organizing section of your local home improvement megastore - mine cost $7.99 at Menards. Save big money at Menards (you will either get that reference or you don't have a Menards, find another store).

Next, I need to figure out where the floodlights will go on the fixture. This is my pilot model, and I decided to use six floodlights, evenly spaced. I'm alternating cool and warm lights.

I marked where the lights go with a sharpie marker - just to make things easier later.

There is a bit of a complication with these units. The cords that come out of them are almost always way too short to do anything useful with. You have two options for lengthing them. First, you could open up the unit and attach a new cord inside (just cut the wires, add new cord with wire nuts, close it back up). If you were curious, this is what the insides of a floodlight look like.

If you do replace the cords, you will almost certainly not have the same size cord as the supplied cord, so the unit will not be water-tight when you are done. I suggest a nice blob of silicone caulk around the fitting. Or, you could do what I usually do, and just add wire to the end of the cord. I use a butt-splice (heh... he said butt... Get over it).

You do need a special tool to crimp the splice onto the wire, if you don't own one you needed a new tool anyway. This is what the splice looks like when you are done. Note the wiring colors. If you are doing this with american wire, our black goes to the brown from the fixture, white goes to blue, and the ground wire (green) is yellow in these fixtures. You might notice in future pictures that the wire I'm using for extensions is jacketed in bright orange, just like an extension cord. That is because it is. 16 gauge extension cord - I had some left over, you'll see why later.

If you want it to look neat, wrap that splice with some electrical tape. You have almost certainly figured out that you could stop here, if you wired a standard plug onto the fixture. I have gotten into the habit of keeping whatever appliance plugs I can find; if I'm throwing something away I'll cut the cord as close to the appliance as possible and keep the cord. You could end up with something like this:

Note that in the above example I have an ungrounded plug. If you aren't sure which wire is which, follow them back from the plug. The narrow prong is the hot (black) wire, the wide blade prong is the white (common). I just cut the ground wire back as far as I can (nothing to splice it to anyway!).

On my fixture I only needed to add wire to the light on the extreme ends. I was able to use the supplied cord for all the other lights. Bonus! This is a good time to spend a little time arranging lights and cords , it is a bit of a puzzle and there is more than one satisfactory solution. In my case, imagine if you will that each half of the fixture (three lights) are wired together, and then those two halves are connected to the input power supply. You could do it some other way, I just found that this arrangement ended up with the fewest splices onto the fixtures. It might be more clear later.

Next step is to attach the lights to the metal bar. I gave this a lot of thought and then went with my usual method - zip ties. Not the most professional presentation, I'll admit, but they are cheap and versitile, plus if I make a mistake I can just cut the tie and use another one. The lights have a mounting bracket built onto them. There are two bolts on either side of the light, loosen them up a few turns so the light can rotate in the bracket, you'll tighten them up later. I used two zip ties per light, and snuggled up my cables in the open back of the channel at the same time.

After all the lights are attached to the bar, and the cords are arranged to your liking, it is time to make the connections. I decided to use 'wall-nuts' - a type of connector that you push a wire into (they won't come back out if you do it right), rather than wire nuts. The small gauge wire used in the flood lights doesn't work well with wire nuts, or at least it doesn't for me. Here is an example:

You might be able to tell, but there are four holes in each of these connectors (you can find them at the megastore). You can get them with more or fewer holes. They are very easy to use, just strip a bit off the end of your wire to expose the copper, and then push the exposed wire into a hole. If you can't pull the wire back out, you've done it right! In this build I used stranded wire instead of solid copper like I usually do. This makes it a little harder. If you are using stranded wire, twist it really tightly before you insert it into the connector. You might have to try a couple times. Examine the above connector. Notice there are three wires (I have three lights - boy that worked well) in each connector. Match your colors! If you have brown and black wires, they go together. At this point, I have three lights on one half of the fixture going to one set of connectors, and the three lights on the other side of the fixture going to another set. We still don't have power!

Extension cords to the rescue. You can certainly purchase a plug at the store and connect it to the end of the wire of your choice, but when I was browsing the aisles the other day I noticed that a 20' outdoor extension cord had plugs built in (both ends), and extra wire to boot. And cheaper than buying the wire and the plugs individually. Two problems solved! I cut the extension cord to the appropriate length - enough to go through my fixture to the point I wanted to connect it to the lights, and enough hanging out the end so I could plug it in to my power outlet. The extra wire is the wire I used to lengthen the flood light cords and also to make connections inside the bar.

I should probably draw a wiring diagram at this point...

Remember that we had one hole left on each of our connectors? I attached a piece of extension cord to each set of connectors (one on either side of the fixture), and those cords meet in the middle of the fixture at another set of wall-nuts. Four holes, one carries a wire from each end of the fixture (that's two). That extension cord with the plug on the end attaches there (that's three). One more hole to use if I want, and I chose to use the other end of the extension cord (the female end) and run that through to the opposite end of the fixture. Now I can plug in another fixture to the end of my first fixture!

A few more zip ties to get all those unruly connectors back into the channel, and I'll cut the ends off the ties to make it look neat. We are ready to hang the light! Better test it first...

Yep. I love it when a plan comes together. This also gives you a good idea of the different colors of 'white' I'm using.

How are we going to attach this to the ceiling? I could just attach the light directly, but the ceiling is a little high and I'd like the flexibility of being able to move the light up and down. So, I attached a 2x2 to the ceiling, and installed three screw-eye hooks into it (probably can't see them in the picture). Next:

The light is suspended from the screw eyes by three lengths of chain. I fiddled with the chain until I had it at the height I wanted (I can easily lower or raise the fixture if I need to later). Then I pointed each flood light in the direction that gave me the best light on the bench surface, and tightened the bracket bolts to hold the lights in that orientation.

The last step! Plants are in place.

Obviously this is just my way to build a multiple flood light system. You could vary the number of lights or the length of the bar. After installing this first build, I decided for this particular shelf (I needed to build two more), and for these particular plants (paphiopedilums), I would use 5 lights per 6 foot section. I'll be keeping an eye on plant growth and blooming. I've had excellent luck alternating bright white 30W units with red 20W units on other shelves, so that might be my backup solution for this shelf if I am unsatisfied with flowering. Note that my application is completely free of natural light, I have no windows in my entire growing area. If I were supplementing some sort of existing natural light (a window), far fewer lights would be required. As always, it is best to hang the lights higher than you think you need, and move them down if necessary.

Enjoy! Hope it was useful. - Rob