Capacitor. RFI suppression capacitor has the following functions in the tube light circuit: a. Absorbs the electric noise created by discharge around the electrodes in order to suppress the radio frequency interference with other electric devices.

Fluorescent lamps form an inductive load on the AC mains supply. As a result large installations of such lamps suffer a poor power factor and resultant voltage drop. Adding a capacitor to each lamp corrects the power factor bringing it back close to unity (1.0).

No high-intensity discharge (HID) or fluorescent lamp is complete without the right ignitor, capacitor, or starter. These types of lights need ballasts to stay on, but they also need a little help to get started or to improve power. Starters work much the same way to light fluorescent tubes.

In more expensive ballasts, a capacitor is often paired with the inductor to correct the power factor. In ballasts that control two or more lamps, line-frequency ballasts commonly use different phase relationships between the multiple 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. Within a second the lamp would overheat and burn out. For more on ballast technology, see NLPIP’s Specifier Reports: Electronic Ballasts.

A choke is an inductor designed to have a high reactance to a particular frequency when used in a signal-carrying circuit. An electrical ballast (sometimes called control gear) is a device intended to limit the amount of current flowing in an electric circuit.

A magnetic ballast (also called a choke) contains a coil of copper wire. The magnetic field produced by the wire traps most of the current so only the right amount gets through to the fluorescent light. That amount can fluctuate depending on the thickness and length of the copper wire.

Explanation: When the switch is ON, in a tube light choke is nothing but the coil/ballast ( inductor) which is used to induce the high voltage across it. Gas discharge process continues and current gets the path to flow through the tube light gas only due to low resistance as compared to the resistance of starter.

2. Look for warning signs that the ballast is failing.

• Buzzing. If you hear a strange sound coming from your bulbs or light fixture, like a buzzing or humming noise, that’s often a sign your ballast is going.
• Dimming or flickering.
• No lights at all.
• Changing colors.
• Swollen casing.
• Burn marks.
• Water damage.
• Leaking oil.

A dead fluorescent can be caused by lack of electrical power (tripped breaker or blown fuse), a dead or dying ballast, a dead starter or a dead bulb(s). Check for power first… then the starter (if applicable) and then the bulbs. When all else fails, the ballast should be replaced.

How to Tell If a Fluorescent Tube Is Bad?

1. Check the ends of the tube. If they appear darkened this indicates the bulb is burned out.
2. Rotate the tube in the fixture if the bulb is not darkened on either end.
3. Remove the bulb from the fixture if the bulb is still not illuminating.

If you can’t find obvious signs of a bad ballast and you’ve already tried replacing the bulb, there are steps you can take to test whether your ballast is the issue….Checking for a Bad Ballast

1. Power off the fixture.
2. Remove fluorescent bulbs from the fixture.
3. Disconnect the ballast.
4. Remove the ballast.
5. Use a multimeter.

Disadvantages of Fluorescent Lighting

• Fluorescent lamps contain toxic materials.
• Frequent switching results in early failure.
• Light from fluorescent lamps is omnidirectional.
• Fluorescent lights emit ultraviolet light.
• Older fluorescents suffer brief warm-up period.
• Ballast or Buzz.

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.

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.

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.