Welcome to my first 'ible. I have done a lot of projects, but this is the first time I've documented one well enough to create an 'ible. The purpose of this was to create an LED lighting fixture that was as bright as a the original fluorescent, and even more economical on power. The side benefit would be getting rid of the need to climb a ladder to replace fragile mercury-filled tubes.
First off, if you are not comfortable working with real electricity, DON'T DO THIS.
Second, read the whole thing before starting work. Some steps are optional and if you actually do some planning, you can probably do this better. This was kind of a seat-of-the-pants proof-of-concept thing.
What I did was to remove all the fittings to hold the fluorescent bulbs and all the normal wiring from an overhead lighting fixture in my kitchen. I replaced them with a self-adhesive string of ultra bright LEDs and an old 12V power adapter from an old cable TV box.
Supposedly one 32 Watt fluorescent tube produces 2600 lumens, and there were two tubes in the fixture. The LED strip is supposed to produce a total of 2600 lumens, but my impression is that the LEDs were brighter than a pair of tubes. Perhaps my eyes adjusted, or the fluorescent tubes may not have been performing as they should. Since the fixture was defective when I started this project I find myself unable to do a comparison. I hope that someone else will be able to do a before and after test.
Step 1: Parts & Tools
The parts that I used included:
- A dead fluorescent lighting fixture ($0)
- A 16.4 foot high density roll of 600 LEDs - 5000K, 164 Lumens per foot ($23)
- A spare 12v power adapter I had laying around ($0)
- Salvaged wiring from an old computer power supply for jumpers ($0)
- A zip tie ($.02)
- A bag of veggie strings as snack food, since I was figuring this out as I went along ($4)
The tools that I used were as follows:
- Wire strippers
- Slip-joint pliers
- Clamping tweezers
- Angle cutters
- Needlenose pliers
- Soldering iron & solder
You may need other tools depending on the model of lighting fixture that you are working on. Other fixtures around my house would have required nut drivers in order to access some of the nuts. On the kitchen one I was able to use slip-joint pliers for all the nuts.
Step 2: Disassembly
This is another point where I will say that if you aren't comfortable with real electricity (AC in the wall) then don't do this. Also, if you are not mechanically inclined enough to strip out the ballast resistor and other wiring from the fixture on your own, you probably shouldn't be doing this yourself. Before you complain that I'm leaving stuff out, I have looked at the three fixtures in my house and they are all quite different. I'm confident that the instructions to disassemble my lighting fixture would bear only passing resemblance to what needs done to clean your fixture of its old guts. I ended up only needing a screwdriver and some slip-joint pliers.
Step number 1 is to find the circuit breaker that controls the thing you're going to work on. Since I was working in the kitchen, I got the unfortunate news that the light above the stove and the one over the sink were all on the same circuit. It crossed my mind that I could possibly work on the lamp wiring by relying only on the light switch for the lamp so that I could still have a couple lights to work by. Then I realized how stupid that would be and left the circuit breaker off while I worked. If you're wondering why I had to use flash... there you go.
Once you have removed everything down to the frame of the fixture, go through the wiring and see if it is suitable for use for jumpers. If so, hang onto it. If not, then you will need another source of wire. I used a bunch of wire that I took out of an old computer power supply.
Step 3: Install LEDs
The string has an adhesive backing. The peel off backing was buckled because the strip is shipped on a spool. It took some work to get the string stuck down well. If I do this again, I will probably add something as insurance to make it stick better.
You don't have to cut the string apart, but I did in order to avoid curving the string. Play with how you want to line them up and see if the bend radius is acceptable. I wanted all the LEDs aimed down because of the way the fixture was designed and I thought the soldering would be pretty trivial for me. If soldering is a weak spot, then you don't need to cut the strip. Just stick it in place and call it good. It was a 4 foot fixture, and I had a 16.4 foot long string of lights so I ended up with a few inches left over after I got them all put in.
The important part is making sure that the power connector is in a good position to reach the power supply.
Step 4: Solder the Jumpers If Necessary
If you cut the string apart, then you will need to make jumpers. Measure the distance you need and use the wire cutters or the cutting surface on the strippers to cut your jumpers. Strip them back about 1/8". Another reason I used the computer wiring was so that I could be careful about the polarity. + is red and - is black. This is important because the way I arranged the light string, I ended up with the polarity reversed across each jumper bridge. That's what happens when you're making it up as you go along.
Put a drop of solder on the ends of the jumpers. This is called "tinning" the leads. I use the clamping tweezers for holding the jumper while I tin it. It normally takes a little while for the flux to get the solder to wick into the strands of the wire. Make sure the soldering iron is hot enough and work quickly. The first jumper I tried to tin was done with an iron that was too cold. I went ahead and held it in place long enough to make the solder flow, and the heat soaked down the wire and melted the insulation. If you do the same thing on the string of lights, you can burn the nearest LED, or melt the solder that holds it in place. Work with a hotter iron and move fast for good technique. Do all of the jumpers before you start tinning the light strip to get "into the zone".
Then tin the copper jumper points. Put a drop of solder on the copper and get a nice shiny little dome.
Having solder on these two parts separately will make it so that you can join them together quite easily. Since you are soldering close to surface mounted components, you don't want to spend too much time soldering and overheat anything.
Then hold the jumper against the solder point (verify polarity!!!!!) and hold the iron against it just long enough to melt the two together. As soon as the solder melts, take the iron off the puddle and hold the jumper in place while it cools. I used the needle-nose pliers to hold the jumper without risk of burning my fingers.
Step 5: 12V Connection
Since the fixture hangs from the ceiling and the top is reasonably well concealed, I decided to just throw a zip tie around the power brick and secure it that way. I ran the 12v connector down a hole in the fixture and plugged it together.
This is the time to test all your soldering. Plug the power brick into a working outlet. I had one in the living room that was controlled by a switch, so I plugged it in there and threw the switch. Everything lit up nicely and there was no sparks.
So far so good.
Oh, and it's BRIGHT!!!
Step 6: 110v Power Connection
The hanging wires were secured to the old fixture wiring with twist caps. If your fixture plugs directly into an outlet in the ceiling then you won't need to cut off the plug. Just use the plug if you can. In this case I had to cut off the plug and strip the wires back the correct amount for the particular twist cap in use. The dangling wires were stripped back 3/4" so that's what I did to the cord for the power brick.
The connector that I cut off the power brick was not polarized, so I didn't worry about polarity at all. I just connected the ceiling wires to the wires of the power brick with the same twist caps that were used for the original fixture.
Once I was confident everything was connected properly, I turned the light switch on and went out to enable the circuit breaker. I watched through the kitchen window for a minute to see that nothing sparked or caught fire. It would have been much faster to get the circuit breaker back off if anything had gone wrong. Nothing did, so I closed the panel on the circuit breakers and went back inside.