Thursday, May 31, 2012

Convert Fluorescent Lights To LED Dual Use

A while back I converted my RVs lighting to use the much lower power consuming LED bulbs. It's easy to swap out a bulb with an LED designed as a direct replacement. Many people wrote me and asked what I did to add LEDs to my existing fluorescent fixtures. This conversion will let you use either the original fluorescent bulbs, the LED strips, both or neither (Off!) When I did the conversion, as usual, many photos were taken. I had a combination of recessed lights and larger flat mounted ones. These tips should be usable for many types of  fixtures. So, here's how to convert your fluorescent fixtures to LED Dual Lights.

First off, you need to decide what color temperature you'd like. Fluorescent bulbs cast a greenish (4300K) light. Not all that flattering. Believe me...I see myself in the vanity mirror in the morning and anything I can do to make it more pleasant is a great boon! You could use Daylight, bluish (~5600K) versions or go with the Warm White (~3200K) style. I prefer these as it most closely replicates regular incandescent bulbs.

Next buy some LED "strips." These are available all over the internet. I bought a 5M (~16 feet) roll of Warm White 5050 SMD strips. These would give me about the same light output as a fluorescent bulb of the same length.

I also purchased a bunch of same size, same style rocker switches to match the ones already installed by the factory in the stock light fixtures. I used simple "on/off" versions, but I could have saved some work cutting and fitting the switches in by replacing the existing switch with a 3 way version but these switches were much harder to find and were more expensive.

You'll need some 20-22 AWG stranded wire, I used black and red to keep the connections more obvious. A 25 watt (or so) soldering iron, some solder (DUH.), a few 1/4" female spade connectors and some heat shrink tubing in the right size. Too big won't shrink enough, obviously. Too small and when you are forcing it on the crimped blade connectors will pull off. Yes...I did this. Twice.

Make the Strips a Bit Longer Than the Bulbs
Begin by measuring the length of the strips you will need for each fixture. I made them a bit longer than the bulbs. Once you've done that, look at the strip closely. You'll see a copper set of "pads" every few inches, this is the ONLY place it is safe to cut. Check your measurements and cut. Then, if your strip is of the waterproof style, take a razor blade and gently cut off the waterproof coating over the copper pads. Put these aside. Now we'll move on to the fixture for a bit.

Two Switches, One for Fluorescent One for LED
First make sure the power is off! Second, remove the lens. Remove the bulbs. Then unscrew the fixture from the ceiling or wall or wherever. This is usually just four Phillips head screws under the lens.

Carefully remove the fixture and let it dangle on the wires. Now, wouldn't it be much easier to cut the wires to the ceiling then replace them later? Sure, but why do things the easy way? At this point we can cut the rectangular hole for the switch. There are a few ways to do this, but the plastic is quite soft and it's simple to drill a few pilot holes and then use a file to get the correct size and shape. I located it opposite the existing switch so it looks factory installed. Then I cut a hole in the plastic "wall" next to the switch to run the positive wires.

See the Hole, + and - Leads?
Next, remove the cover over the electronics and wiring. This is usually the center between the bulbs on a twin bulb fixture. If you gently press inward, toward the middle, the center should come out of the tabs holding it down on one side. Repeat for the other side. It should now be free from the fixture. Put it aside. You'll see the ballast electronics (this it what lights the bulbs by converting the 12V from you system to the HIGH voltage needed to start and run the fluorescents) Be careful, you could get a nasty shock if you forgot to turn off the power or disconnect the wires! Also located here are the main Power and Ground wires that come into the fixture from the coach. We will be tapping into the ground wire here. The power will come from the hot side of the main switch.

Take some wire (I used BLACK for negative) and measure how long it needs to be to get from each side of the strip to the center of the fixture where we will tap into the negative wire that's already there. Cut them. Now do the same for the positive (RED) wires. I went from each strip through a hole I drilled and connected it to the switch for the LEDs

LED Strips with Soldered Wire Leads Attached
Now go back to the strips you cut earlier. Set up your soldering iron. Make sure you have some thin solder, if you don't, or think you do, you will end up driving back to the store to buy some. (I wish you could see me shaking my head. Yes, sometimes I forget stuff.) While the soldering iron is heating up, tape the strips to your work surface so they don't move. You will be melting a tiny pool of solder onto the copper pads marked POSITIVE (+) and NEGATIVE(-) though it could say GROUND or simply "G". Heat the pads with the soldering iron and put a small bit of solder on each pad. Next, take the 2 positive (RED) wires and the 2 negative (BLACK) that you have already cut and strip one end of each about 1/8" and the other end about 1/2". Now, heat each end in turn with the soldering iron and melt a bit of solder on each wire end.

[**TIP - When the wire is hot enough and the solder touches it, it will get "sucked" up into the wire like magic.]

Now heat up both the strip's pad and the short wire end. When they are hot enough they will join and be permanently attached. Make sure the solder melts thoroughly on both or the joint will be weak. When I did the first fixture I tried to do this while it was hanging and it was impossible to get the soldering done properly. Put a piece of heat shrink tubing over each assembly and shrink to fit.

Back Together
Now remove the paper cover from the sticky back of a strip and affix it to the inside of the fixture. Mine had natural bevels where they fit perfectly. Press the switch into the hole you made. Route the positive wires through the hole you drilled slide on a piece of heat shrink tubing and crimp a 1/4" female blade connector on to both positive wires (one connector two wires!) shrink to fit then slip the female spade onto the normally off side of the switch.

Now find the ground wire in the center of the fixture (or from the coach) and tap into it. You could use various crimp on connectors or simply scrape off some of the insulation and twist the negative wires to the existing ground wire. Since they are already covered in solder, you can just heat it up until a solid connection made and cover with tape. Once done, tuck all the wires into the center and replace the center cover. Lastly, measure another piece of positive (RED) wire from the other spade connector on the new switch to the positive wire from the coach. I tapped into it at the hot side of the existing switch. Cut and crimp on a 1/4" female spade. Slide on a piece of heat shrink tubing and shrink to fit. Run the wire along-side the fixture and up to the power source. It's a good idea to use a piece of tape on the side of the fixture to stop the wire from "flopping" around. It will make it easier to re-install the light!

Ta Da!
Now put the whole thing back in the ceiling. make sure both sides clear any material in the roof and screw the fixture in. Replace the fluorescent bulbs. With the cover off, turn on the fluorescents with the old switch. Did they work? Excellent! Turn them off. Now for the moment of truth. Turn on the new switch. The LED strips should light up. If they did...congratulations. If not, figure out where you went wrong. Good places to look are solder joints and positive/negative wires being backwards. Of course, you could test the LED strips with the fixture dangling and maybe save yourself some extra work having to remove it again, but do it your way....

Finished Fixture With Lens In Place
All in all, I am very happy with the conversion. Same amount of light. Much "warmer" and inviting than fluorescents AND I look better in the mirror. Hey, every little bit helps!

The cost to do this was minimal. Figure less than $20 per fixture. The LED's will last far longer than the fluorescent bulbs, use less power and look better. AND if you use this install method you get to keep the use of the fluorescent bulbs.

Be Seeing You...Down The Road...

Rich "The Wanderman"


  1. I have been trying to figure a way to avoid the $40 per LED tube, this will work great and it appears fairly simple to do. Excellent idea. Thanks
    02 Endeavor 40dst

    1. Walt,
      I couldn't agree more. The strips INSIDE the LED "tubes" are the same as these. AND you get to keep your fluorescents operational. What's not to like! :)




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