How to Fix or Replace a Florescent Light Ballast (with pictures)
Posted By admin on December 20, 2009
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Almost every home in North America probably has some form of fluorescent lighting, often chosen for its low power consumption. Anyone can change a light bulb, but do you know how to change a ballast?
What is a ballast?
From Everything you need to know about Fluorescent Lights
| Quote: |
| A ballast is an electrical component used with a fluorescent bulb (or mercury vapor lamp or arc lamp) to conduct electricity at each end of the tube. It supplies the initial electricity to the bulb that creates light, and then it regulates the amount of electricity flowing through the bulb so that it emits the right amount of light. |
When to change your ballast?
Great, So I know what a ballast is, but when do I need to change one?
A ballast can last for years without problem, but sometimes that’s not the case. I have ballasts in my home that are going on 12+ years without any problems.
I change my ballasts when either they fail (light dose not turn on, acts as if one of the tubes is burnt out, but after replacing the tubes, the light still doesn’t work) OR you can change them when the light flickers and wont provide a constant light.
Purchasing a new ballast
When replacing the ballast, you will need to purchase a new one (obviously 
). Here is what to look for,
Lamps are typically identified by a code such as F##T##, where F is for fluorescent, the first number indicates the power in watts (or strangely, length in inches in very long lamps), the T indicates that the shape of the bulb is tubular
What kind of tubes do you have?
The two standards are T12’s and T8’s. A T12 has a diameter of 1½” or 38 mm and a T8 is 1″ or 25mm. A T12 is most common in residential housing while T8’s are used for commercial energy-saving lamps. A T12 requires a bigger ballast than a T8.
How many tubes do you need to power?
Are you just powering one tube? or dose your lamp have two?
How many watts is each of your tubes?
Are they 32 watts? 34 watts?…
After you have gathered this information, you need to find the ballast that suites your needs, for example,
If I had a lamp that had two T12’s at 32wats,
I would need to find a ballast that can power (2) F32T12
F = Watts,
T = Type of tube
and I have TWO (2) of them to power up. This information is found on the ballast.
Replacing the ballast
Alright, now the part you have all been waiting for, the actual changing out of the ballast
1)Power Off – The first thing we need to do is to make sure the power is OFF to the light fixture we are working on. Make sure the switch is off to the light and then at you have turned the power off from the circuit braker.
2)Remove deffuser shield and tubes – Most fixtures have a plastic deffuser shield to help spread the light, remove this and the tubes (the twist off)
3)Compare the old with new – Compare the old balast you purchased with the new balast and make sure they are both the same.
4)Disconect the wires – Follow the wires ont he ballast untill you find wire nuts connecting like coloured wires togther, If there are not wire nuts you will have to cut the wires about 12 inches from the center of the fixture on each side, complete this for all the wires.
5)Remove Ballast – Unscrew the holding nut from the ballast and remove it from the fixture.
6)Install the new ballast – Install the new ballast into the fixture and be sure the red and blue wires face the end with red and blue wires while the black and white face the other end.
7)Cut Wires – Cut the wires so they overlap by about 6 inches
8 )Strip Wire – Strip about 1/2″ of insulation off the ends of all 8 wires.
9) Connect Wires – Using a wires nut, connect the blue wire to the blue wire, red to red, white to white, black to black and so forth. If your new ballast has different colored wires, then follow the diagram on the ballast.
10) Reassemble Fixture – Reverse step 2,
11) Reinstall new tubes & turn power back on – Thats self explanatory 
After you have completed these steps, you should have a working florescent lamp, if not, then check to make sure you have the wires connected correctly, its usually just a case of a crossed wire..
Questions & Comments: Please feel free to add your comments and questions below.
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