Energy Efficient Fluorescent Lighting

Skill Level: Intermediate

by Casey March 10, 2009 | 18 comments

Saving the World, One Light at a Time

SparkFun is currently participating in a program started by the city of Boulder called 10 for Change. The challenge is for local businesses to reduce their energy consumption by 10% within one year. There is lots of talk in the 'green industry' of picking the low hanging fruit first. This means instead of jumping to large changes right away like installing a photovoltaic system or new heating units, first make small changes that have relatively quick payback for the investment. Some of the small changes include motion sensing light switches for rarely occupied rooms, learning how to use programmable thermostats and, the topic at hand here, updating old fluorescent lighting systems.

Note: We post these tutorials in the spirit of giving people knowledge and a documented example in order to attempt a project that they may have been apprehensive to try in the past.  If you are not comfortable working around fuse boxes, lighting fixtures, testing voltage of a lighting circuit or confident in your ability to SAFELY test to see if a lighting wire is powered, please contact a professional about making the changes outlined below.

Old vs. New

Older fluorescent fixtures use magnetic ballast and a bulb known as a T12.

The ballast looks like a black brick mounted in the center of each fixture, this controls the electrical output to the light tubes. There is typically one ballast per two bulbs. A single new ballast can power four bulbs.

The T12 denotes the bulb has a diameter equal to twelve eigths of an inch or 1.5 inches  (12 * 1/8" = 1.5"). Newer and more efficient systems use an electronic ballast and a T8 bulb...you guessed it, a bulb with a one inch diameter. Why are these so great? I don't know what is different inside but the US Department of Energy tells us that a retrofitting an old system with the magnetic ballasts and T12 bulbs to an electronic ballast and new T8 tubes is from 12% to 30% more efficient.

The folks Universal Lighting Technologies put together this great example showing what really matters...how much money you can potentially save-

Example:
Existing System:
4-Lamp F34T12 Lamps and magnetic ballast
Power consumption: 148 Watts

    <p><u>Replacement System:</u><br>
      4-Lamp F32T8 Lamp with High Efficiency ballast<br>
      Power consumption: 96 Watts ? 52 Watt savings (35% reduction)<br>
      Light Level: Increase by 3% to 12% depending on lamp used</p>
    <p><u>Alternate Retrofit Options:</u><br>
      4-Lamp F28T8 Energy Saving Lamp with High Efficiency ballast<br>
      Power consumption: 84 Watts ? 64 Watt savings (43% reduction)<br>
      Light Level: Decreases by 3% - Improved color quality may provide better perceived lighting.</p>
    <p><u>Energy Savings Equals Dollars</u><br>

Based upon the annual operating hours and utility rate, the energy savings can be used to calculate the operating cost savings:

Multiply this value by the number of fixtures in the facility to determine the total cost savings.

The chart below identifies some of the savings potential with T12 to T8 retrofit, keeping the number of lamps the same:

      <table style="border: 1px dashed #AAAAAA;" align="center" border="1" cellpadding="0" cellspacing="0"><col width="60">
      <col width="60">
      <col width="60">
      <col width="60">
      <col width="60">
      <col width="60">
      <tbody><tr height="20">
        <td style="border: 1px dashed #AAAAAA;" colspan="2" align="center">Existing System<br>
          F34T12 Lamps</td>
        <td style="border: 1px dashed #AAAAAA;" colspan="4" align="center">High Efficiency Electronic System<br>
          F32T8 Lamps            F28T8 Lamps</td>
      </tr>
      <tr height="20">
        <td style="border: 1px dashed #AAAAAA;" align="center">Lamp<br>
          Quantity</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">Power<br>
          (Watts)</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">Power<br>
          (Watts)</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">Energy<br>
          Savings</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">Power<br>
          (Watts)</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">Energy<br>
          Savings</td>
      </tr>
      <tr height="20">
        <td style="border: 1px dashed #AAAAAA;" align="center">1</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">44</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">25</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">19</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">21</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">23</td>
      </tr>
      <tr height="20">
        <td style="border: 1px dashed #AAAAAA;" align="center">2</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">74</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">48</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">26</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">43</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">31</td>
      </tr>
      <tr height="20">
        <td style="border: 1px dashed #AAAAAA;" align="center">3</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">118</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">73</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">45</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">65</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">53</td>
      </tr>
      <tr height="20">
        <td style="border: 1px dashed #AAAAAA;" align="center">4</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">148</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">96</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">52</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">84</td>
        <td style="border: 1px dashed #AAAAAA;" align="center">64</td></tr></tbody></table><br><hr style="width: 100%; height: 2px;"><h3>The numbers</h3>In the chart above you maybe noticed some other classifications of the lamps - F32T8.  The "F' denotes a fluorescent bulb and the '32' or '34' denotes the wattage. I know the wattages do not exactly add up (2 * 32 = 48?), this is because adding more bulbs increases the over all efficiency.  More bulbs working together need less power...kinda like the more people you have out <a name="" target="_blank" classname="" class="" href="http://travel.webshots.com/photo/2106027530067323977iEWTEw">pushing your bush taxi</a> (and not sitting inside of it) the easier it'll be to get it out of the sand dune.  Yea, kinda like that.<br><br>The big number to notice is the annual cost savings, about $31 a year. I just walked around Spark Fun, we have 85 light fixtures on during the day, that's a potential savings of $2635 a year.  After 50 years that could get us a new pick and place machine!  Of course you have to account for the cost of replacing the whole set up.  Companies around here quote $100-120/fixture for the retrofit, we can do way better-<br><br>Ballast -                     $38<br>New Tubes-            $16 (at $4 each)<br>Xcel rebate- ($22)<br>Total-                            $44<br><br>So in a little over one year the investment is paid back, even with the high prices of the new equipment I chose. That is very attractive comparing to PV systems that can take 10-20 years for a return on the investment.  But, besides the money savings, we are also cutting down on the carbon footprint of our building.  All these little perks...why wouldn't you do it?!<br><br><hr style="width: 100%; height: 2px;"><h3>Let's get down to it!</h3>Here we go. First you'll need to purchase the new <a name="" target="_blank" classname="" class="" href="http://www.google.com/products?q=T8+ballast&amp;hl=en">ballast</a> and <a name="" target="_blank" classname="" class="" href="http://www.google.com/products?q=T8+bulb&amp;hl=en">tubes</a>. You can find these on-line or at your local hardware store. Be sure to purchase a ballast that is correctly rated for your system, some offices use 270V for lighting systems...a surprise to me.  I have seen some for around $20 that will handle 120V and 270V, best to have all your bases covered.<br><br>Now that you have all the hardware, open the fixture that you want to retrofit.  There are usually little latches along the outer frame of the fixture that make this easy to do. Once opened, take out the old lamps/tubes/bulbs, most of them need a quarter turn then they slide downwards out of the sockets at each end.&nbsp; Put them off to the side for now...we'll deal with them later.<br><br><div style="text-align: center;"><a name="" target="_blank" classname="" class="" href="http://www.sparkfun.com/tutorial/BallastRetrofit/Pics/new_ballast_1.jpg"><img alt="The image ?http://www.sparkfun.com/tutorial/BallastRetrofit/Pics/new_ballast_1-s.jpg? cannot be displayed, because it contains errors." src="https://www.sparkfun.com/tutorial/BallastRetrofit/Pics/new_ballast_1-s.jpg"></a><span style="font-weight: bold;"></span><br></div><div style="text-align: center;">Exposing the ballasts<br></div><br>Typically the ballasts are hiding under the covering right in the middle of the fixture. These are mounted in various ways but almost always come out with a squeeze. In the one pictured above, there were four little tabs, located near the red arrows. By squeezing the middle spine part the whole piece comes out to reveal...<br><br><div style="text-align: center;"><a name="" target="_blank" classname="" class="" href="http://www.sparkfun.com/tutorial/BallastRetrofit/Pics/new_ballast_2.jpg"><img alt="http://www.sparkfun.com/tutorial/BallastRetrofit/Pics/new_ballast_2-s.jpg" src="https://www.sparkfun.com/tutorial/BallastRetrofit/Pics/new_ballast_2-s.jpg"></a><span style="font-weight: bold;"><br></span>All the guts<br><br><div style="text-align: left;">...the ballasts and a bunch of wires. <br><br><span style="font-weight: bold;">NOTE: </span><span style="font-weight: bold;">If you haven't already thought about safety, we </span><span style="font-weight: bold;">want to address that now. Since we are rewiring this fixture we need to be sure THERE IS NO POWER COMING TO THE LIGHT!! I recommend you are sure of this by finding the breaker that controls the circuit this light is on and kill it. </span><br><br>A Sparkfun user suggested this simple and effective way to keep yourself from getting shocked-<br><br>- Turn the fixture on.

- Turn off the breaker controlling the fixture.
- Verify the fixture is off.
- If other people will have access to the panel while you're working, tag the breaker with your name (masking tape works) so they know who to find before turning it back on.
- Verify at the fixture with a DVM or other test device that the power really is off.

Ok, now that we've covered our butts, lets move on.

Capping the power leads

The next thing I like to do is disconnect the power leads and cap them just in case someone decides to be a wise guy (or gal) and flip the power back on. Find where the power comes into the fixture (usually a little silver plate that has a hole in it with three wires coming out). You can see this hole (in the picture above) just under the largest arrow.  Hopefully these wires are black, white and green. If not, find the one that is screwed to the metal fixture (in this picture the green one, the ground wire). Now clip the other two wires close to the existing ballast. I suggest you clip them one at a time and cap or tape each one just after you cut it. Now that the power leads are capped you can work with relative comfort of not being zapped, just be aware if your caps or tape get knocked off some how.

Next we are going to take out the old ballast.

Old ballast removed with the leads clipped

Snip all the leads coming out of the old ballast. I like to cut them very close to the base leaving lots of spare cable to work with in the fixture. If you are planning to reuse these I would leave 1-2 foot long leads. There should be a small screw or nut on one end of the ballast that you need to unscrew. The other end is held in with small corner brackets similar to the ones in old photo books (like ones your grandparents have of your parents visit to the grand canyon). The ballast should slide right out.

Light fixtures ready for new wiring

If there are two ballasts in your fixture clip the wires and remove both of them. You should now have a blank fixture ready for some new hardware.

We are now ready to rewire the socket assemblies for the new ballast. Older ballast required four wires connected specifically to each lead on the bulb (two on each end).

Wiring diagram for the new ballast

You can see on the new ballast that we only need to connect one lead to each end of the bulb (circled in red above). We are going to take out the socket assembly to reduce the wiring and make this look as professional as possible.

 Removing the socket assembly

There are some variations on how the assembly is held in place. This one was relatively easy to take out. If you have this same style, there are two little tabs (just inside of the left and right sockets) that hold the assembly in place. To remove this, insert a flat head screwdriver in the slot toward the center of each tab and twist it. Do this on both ends and the assembly should pop right out.

A different socket assembly

The socket assembly above was a little different. You can see the tab (near the red arrow) was bent over top lip of the assembly, to remove this you'll need to get some pliers in there and bend the tab open to get the assembly to come out. A little more difficult but still possible.

The wiring side of the socket assembly

Once you have the assembly out, it should look something like this. Now we can get down to rewiring this little guy. You should be able to pull the individual sockets out of the assembly, this way they will be easier to work with.

Pulling wires out of the socket

Next we need to pull the wires out of the sockets. Inside each of the contact holes there is a small locking mechanism. Somewhere near each hole there is a small passageway just big enough to shove your tiniest precision screwdriver in there. I found the flat head worked best. Pushing your screwdriver in the little passageway will disengage the lock mechanism and enable you to pull the wire out.

Using my super human strength to crush this different style socket (not really)

Pictured above is a different style socket. You can see the passageway to unlock these wires was to the side a little and angled into the locking mechanism.

Socket with my yellow jumper

The easiest way I found to create the proper wiring was to cut a little jumper from the cables we just pulled out of the sockets. Here I began color coding the cables to keep them straight and to match them with the wires from the ballasts. This end of the ballast has all yellow leads. This will help you later when wiring to the ballast.  

Socket with the installed jumper

The jumper only needs to be 2 inches long with a fair bit (almost 1/2 an inch) stripped off of each end. Bend this into a U-shape and push it (good and tight) into the holes that are closest to each other. Some of the other style sockets have an oval shaped hole for wires, two leads will fit in each of these holes so go head and place the jumper in these if that's the style you have.

 

Rewired socket assembly

Make jumpers for all four of the sockets then strip the ends four long pieces (12 inches or more) of the same colored wire. Insert these into one of the remaining holes in each socket. Now the sockets are correctly wired for the new ballast. I found it helpful to twist the long leads of each side together since there is only one lead from the ballast for each side (set of two sockets). Bending these twisted pairs through the large half circle in the socket fixture sets you up for easy reinstallation.

Ahhhhhh, who turned the power on?!?!

Ok, no one really turned the power back on mid-installation, but be sure yours is off!

The other assembly removed

Go ahead and pull the other socket assembly out, it will probably look similar to the one above. When rewiring this assembly, make sure you remove the wires connection the two sides together (the black wires in this picture). If you don't remove these wires the bulbs will not work when you reassemble the fixture.

The second completed socket assembly

Rewire this one in the same manner, I color coded this one again with the wire that was pulled out of the same sockets. I don't think it matters which side is red or blue, just as long as the two sides are not connected to each other.

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Reassembly

Now that the socket assemblies are rewired, we can put those back in.

Everything back in its place

To do this just complete the removal instructions in reverse. As well you can put your new ballast in place. It should fit in the same tabs that the old ones were in. I would install it near where the power leads come out of the fixture (the same little silver plate with the three wires coming out).

Since you color coded the leads coming out of the sockets, wiring to the new ballast should be a breeze. Start with the red and blue ones first. I like to use twist on connectors since they are quick and offer a solid connection. After the blue and red leads coming off the ballast are connected move to the yellow ones. I save the black and white (power leads) for last just so everything else is in place before playing with the power leads.

Everything connected and powered-up! It's alive!

Before replacing the ballast cover I like to install the bulbs and make sure everything works. In this case it worked right away. If you have problems, check your connections between the ballast and sockets. If one set/side of the bulbs isn't working that gives you a good idea of the wires to check. If the connections are all ok, I would next check that all the wires and jumpers are fully pushed into the sockets. Checking this requires removing the socket assemblies again.

Preparing to replace the ballast cover

Once everything is working correctly, bundle the wires together in the center. The should be pretty stiff and stay relatively put. If not you can use a wire tie (zip-tie) to hold them together. Doing this allows for easy reinstallation of the ballast cover.

....and all the kings horses and all the kinds men, put the light back together again.

All said and done, you should have just as much (if not more) light and a more efficient lighting fixture (a good selling point if you own the building!)

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Now what?

All finished right? Almost. Now we have a few old ballast and light bulbs to dispose of. 'Well I'll just toss them in the dumpster' you say. That will work, but there are very useful magnets in the old ballasts and a small amount of mercury among the who-knows-what-else inside the bulbs. We recommend proper disposal of these items. Many local recycling centers are set up to take this type of refuse. We are trying to lessen our impact in the environment after all!

If you live in the Denver metro area (or near Omaha, Nebraska), Guaranteed Recycling Xperts has set up a fantastic operation that can process most things electrical. Their website states last year they processed 10 million pounds of electronic waste. If you take a look at around the website, they also explain where they ship all the materials for processing. This is an important factor in dealing with the global 'e-waste' problem that is emerging. There has been documentation outlining how some 'recycling' companies send boat loads (literally) of e-waste to third world countries where workers use acid baths or roadside fires to harvest useful materials, including the 5 lbs of lead in a typical CRT. These processes have created a situation that has made some neighborhoods very dangerous to live in. Please, don't take our word for it, do some investigating yourself! There has been lots of recent media attention and documentaries posted on line drawing attention to this topic.

As for recycling your own waste, here are some good places to find a local recycling center-

Guaranteed Recycling Xperts - A great place and great example of proper recycling
EPA List of Recycle Centers - A list of recycle centers by state

If you find any interesting information about recycling or energy reduction in general, we'd love to hear about it!