How does the ballast work in a fluorescent light?

Asked by: Kathy Gleason

In a fluorescent lighting system, the ballast regulates the current to the lamps and provides sufficient voltage to start the lamps. Without a ballast to limit its current, a fluorescent lamp connected directly to a high voltage power source would rapidly and uncontrollably increase its current draw.

How does a fluorescent tube ballast work?

In its simplest form, a ballast uses magnetic energy that erupts into the lamp when it is turned on, stimulating the electrodes to make a current and the lamp glows.

How do you test a fluorescent light ballast?

Your other test lead to the wires. And see if your meter still reads open line it should read open line open line if you have an analog meter it should not move.

How do you know if a ballast is broken?

If your fluorescent lighting is displaying any of the signs below, it could be a symptom of a bad ballast:

1. Flickering. …
2. Buzzing. …
3. Delayed start. …
4. Low output. …
5. Inconsistent lighting levels. …
6. Switch to an electronic ballast, keep lamp. …
7. Switch to an electronic ballast, switch to a T8 fluorescent.

What happens when a ballast fails?

The ballast itself can go bad, which causes lights to flicker or even appear to be burnt out, when in fact they aren’t. They require maintenance and energy to power, on top of the power used to light the fluorescent bulb. They are a large part of the equation when using fluorescent lamps.

Will a fluorescent light work without a ballast?

All fluorescent bulbs require a ballast. All compact fluorescent (CFL) bulbs require a ballast, which is often integrated. All HID bulbs require a ballast, which is sometimes integrated. No LED bulbs require a ballast, although some are engineered to work with an existing ballast.

How do you check a ballast?

To measure it, set your digital multimeter to around a thousand ohms resistance setting. Connect the black leads to the white ground wire on your ballast. Afterward, test every other wire with the red lead. When you do this test, a good ballast will return an “open-loop” or max resistance.

Why do fluorescent lights not turn on sometimes?

If a fluorescent tube neither lights nor flickers when switched on, first check to see that the fixture is plugged in and that no fuse has blown or circuit breaker has tripped. If this does not help, try wiggling the tube gently in its sockets by rocking it back and forth and from side to side.

How long do fluorescent ballasts last?

12 to 15 years

According to the Certified Ballast Manufacturers Association, the average magnetic ballast lasts about 75,000 hours, or 12 to 15 years with normal use. The optimum economic life of a fluorescent lighting system with magnetic ballasts is usually about 15 years.

Why does my fluorescent light work sometimes?

A flickering fluorescent bulb means that it or one of a dependent pair of bulbs in the fixture has bought the farm. In many fluorescent fixtures, power is sent through a pair of bulbs. If either bulb is bad, they may both flicker or one may flicker and the other show no life.

How much does it cost to replace a ballast in a fluorescent light?

A replacement ballast costs about $10-25 depending on capacity and brand. The bite is that an electrician trip charge (which includes 30 or 60 minutes work) is going to be $75-150 probably – for about 5 minutes work on each light fixture.

Can you replace a ballast yourself?

A typical ballast will generally last about 20 years, but cold environments and bad bulbs can decrease this lifespan significantly. You can get a new ballast at a hardware store or home center and install it in about 10 minutes.

How do I know if my ballast is T8 or T12?

If no markings are available, the size in diameter of the tube is the easiest way to determine the type you have installed. T8 tubes are 1-inch in diameter and T12 tubes are 1 1/2 -inch.

Can a ballast be repaired?

While simply swapping burned out bulbs in an existing ballast is deemed “ballast repair” by many – and can offer advantages in longevity and energy savings – sometimes this simple “fix” is not enough.

How do you fix a dead ballast?

We can cut any wires that are holding the ballast in place. And once we've done this we can go ahead and remove the ballast. From the lighting fixture. Guys once you have the bottles removed.

Will a bad ballast burn out bulbs?

Causes of Ballast Failure



When it’s too hot or too cold, the ballast can burn or fail to start your lamps at all.

How do you change a ballast without turning off power?

Remove the wire nut from one of the power wires and carefully strip about 1/2 inch of insulation from the end, making sure not to touch the end. Hold the ballast wire next to this wire with the stripped ends parallel but not touching. Quickly slip on the wire nut and screw onto the ends.

Can a fluorescent ballast shock you?

UL said in a release that its recent testing confirmed that luminaires with magnetic ballasts intended for F40T12 fluorescent lamps may pose a risk of electric shock during installation of LED lamps intended for direct substitution of a fluorescent lamp while the circuit is energized.

How do you fix a flickering fluorescent light?

Brush dust out of sockets, then reseat firmly. If the tube still blinks when the light is turned on, wiggle it a few times while the light is on to see if this cures the problem. If not, take the tube out and inspect sockets closely to see if spring contacts are bent or corroded.

What does it mean when a fluorescent light flickers?

If your fluorescent bulbs flicker, most likely the problem is with the bulb itself. If the bulb is very dark on either end, it may be defective and burned out. The best way to test the functionality of a bulb is to put it into a fixture you know works.

What are the common problems of fluorescent lamp?

Common Faults and Treatment Methods of Fluorescent Lamp