What is a Ballast in a Light Fixture? Detailed Explanation of Function and Operation

For people who don’t even know what is a ballast, this comprehensive article “What is a ballast in a light fixture” can help you figure out the crucial functions of ballasts, how they work, and different types. First, let’s delve into the ballast definition together and get basic knowledge about what we’re mentioning.

What is A Ballast?

A ballast in a light fixture is an electrical component that regulates the current and voltage supplied to certain types of lamps, particularly fluorescent and HID lights. It serves two primary functions: providing the initial high voltage necessary to start the lamp, and then controlling the electrical current to maintain stable operation, preventing the lamp from drawing excessive power and burning out.

Types of Lighting Ballasts

There are three types of lighting ballast based on two types light fixture families (fluorescent and HID) that work with them:

Lighting ballast	Features	How it works
Magnetic Ballast	Mostly seen on older lamps Use a simple core and coil assembly Provides relatively inexpensive and reliable operation Features a typically bulky design May cause flickering lights  during the startup	Use a magnetic field to resist changes in the current flow
Electronic Ballast	Offers improved energy efficiency Reduces flickering and noise Enables faster startup time Suitable for both fluorescent and HID lights	Utilize electronic components to control the flow of electricity
Hybrid Ballasts	Feature both electromagnetic and electronic ballasts	Use both magnetic field and electronic components to control and regulate the current flow

Magnetic Ballast

As the name suggests, a magnetic ballast, using the oldest technology - magnetic field to control the current flow, is usually found in the fluorescent family such as T12 linear fluorescents, two-pin CFLs, some metal halides, and HPS lamps. Magnetic ballasts are bulky and often cause buzzing and flickering. Nowaday, magnetic ballasts are often found at antique or old lamps because they are replaced by modern technology ballasts - electronic ballasts.

Electronic Ballast

Contrary to magnetic ballasts, electronic ballasts employ modern technologies that are smaller and offer better energy efficiency. Moreover, electronic ballasts have the ability to prevent the lamps from flickering and buzzing by putting out multiple currents without altering the input voltage.

Hybrid Ballasts

Hybrid ballasts combine both magnetic and electronic ballasts features. That means hybrid ballasts have both magnetic and electronic fields as their components to control and regulate appropriate currents.

Besides, we can categorize ballasts in terms of starting technology:

Emergency Ballasts

Emergency Ballasts are used in emergency lighting systems, allowing light fixtures to operate automatically in emergency battery mode during the event of a power failure to provide illumination.

Instant-start Ballasts

By providing a high-voltage burst of electricity that lights filaments and gas inside bulbs without preheating the electrodes, instant-start ballasts can save quite a bit of energy overall. But, we should notice the adverse effect of this type of ballast, which is wear on the bulb filaments over time leading to shortening the lifespan of the light bulb.

Programmed-start Ballasts

Programmed-start Ballasts keep the electrodes preheated through a constant low-voltage current. As the light fixtures are turned on,  a higher voltage current is employed. Although this type of ballast is not as energy-efficient as the instant-start type, it helps the lamp have a longer lifespan. In addition, it’s suitable to be attached with lights that have motion-activated sensors that will be turned on and off many times a day.

Moreover, we can categorize ballasts in terms of light bulbs:

Standard Light Ballasts

Standard light ballasts act as electrical resistors, used with neon and some LED lights to limit the amount of current running through the lamp's circuit at the appropriate level and at lower power draw levels safely and consistently.

LED Light Ballasts

What does a ballast do for LED lights? Due to simple LED light circuitry (and its associated driver), LED lamps use a low-voltage current to operate. Even so, LED lights still need a ballast that can work as a basic resistor to adjust the flow of mains power flowing through its circuitry.

Fluorescent Light Ballasts

The function of ballast in fluorescent lamps is to act as an electrical reactance element hence their operation principle relies on gas discharge, leading to more power needed. Using fluorescent light ballast may prevent the lamps from destroying themselves by allowing the voltage to drop across a completed circuit without a runaway increase in flowing current.

HID Light Ballasts

Although HID (high-intensity discharge) light ballasts operate in the same way as fluorescent ballasts do, they have more complicated circuitries and can convert a DC to an AC. They also have ultra-precise current regulation, allowing turning on and off quickly without excessive wear and tear.

Compact Fluorescent Lamp (CFL) Ballasts

CFL ballasts are designed exclusively for compact fluorescent lamps. These high-efficiency ballasts offer superior energy savings and fewer voltage fluctuations than other types of ballast.

How Does A Ballast Work?

Similarly to how a car’s engine works during ignition and subsequent idling,  a ballast in a light fixture is a two-job component, including boosting and pulling back initial current flow to ensure the lamps can work properly.

As soon as you switch the lamp on, a ballast offers enough voltage to run through the circuit by boosting the initial voltage supply immediately, giving light. Besides, a ballast is also capable of making sure the lamp doesn't take in so much voltage that leads to burning out. Especially for fluorescent lamps, which inherently have a negative resistance, meaning they will continue taking in voltage until the power supply can't take anymore, ballasts are heroes for supplying the opposite resistance - positive - to restrict the current.

To explain in a simple way,  ballasts contribute to the lamps' start-up process by using magnetic energy that erupts into the light so that it can stimulate the electrodes to make a current and the light glows. Technology development changes magnetic energy to electrical energy that leads to many positive attributes such as energy efficiency, reduced flicker of light, and even dimming capabilities.

In addition, for the purposes of dimming, ballasts can work in combination with a dimmer to adjust the brightness of the light fixtures having HID and fluorescent bulbs.

Why Use A Ballast in a Light Fixture?

To understand more about what is a ballast in a light fixture, let’s dig into the detailed advantages below and empower yourself with the idea of optimizing your lamp with a ballast. A ballast is the most popular use as the key component used in fluorescent lamps as they cannot regulate current on their own. The outstanding functions of fluorescent lamp ballasts make them indispensable.

Regulates Current

Ballasts have become a crucial component of certain types of light fixtures such as fluorescent, HID (high-density discharge), and some LED (light emitting diode) lamps for many reasons. The main power supply commonly provides a much higher current than light fixtures needed. Some lamps require a greater and a lower current when turning on and after operating for a while.

Referred to as a control gear, ballast is a type of electrical resistor or reactance, the key feature that helps to control and regulate appropriate supplied current to suit the lamp type during varying voltages and operating phases.

The significant purpose of ballasts is to regulate the current that flows through the light fixtures for both start-up and during operating processes by lowering the current to the optimal operating level, maintaining steady current flows. Ballasts reduce overheating and electrical surge failure, sustaining the lights' long life span and stable performance.

Stabilizes Light Output

Ballasts can contribute to maintaining appropriate current during operation and hold a consistent level of brightness without flickering or fluctuations. This stability contributes to visual comfort, eye health, and energy efficiency.

Starts the Lamp

One of the crucial functions of ballasts is to kick off the electrical discharge and light the lamps, especially those that require a stronger voltage to initiate the ionization process such as Fluorescent and HID lamps. The ballast quickly provides sufficient voltage to start the lamp and ensures the lamp stays light via controlling energy distribution within the fixture during start-up.

Extends Lamp Life

A ballast provides a proper amount of electricity needed, which prevents the light fixtures from damaging its inner components, and even more serious situations such as catching fire and explosion. This function prolongs the lamp’s life span.

Works with Dimmers

Some ballasts can also be used in combination with a dimmer, allowing the brightness to be adjusted for HID and fluorescent bulbs.

Bottom Line

Overall, ballasts play an important role in maintenance, or upgrading systems to more energy-efficient solutions. Hope this article can give you an ultimate summary of what is a ballast in a light fixture. Guessing that we have the same perception that ballasts are unsung heroes of any lighting fixtures, especially fluorescent and HID families.

FAQs

Do all light fixtures have a ballast?

Of course not, some modern lamps already employ components which used to regulate the current flowing into them. For instance, some incandescent and halogen lamps do not require a ballast.

What happens when a ballast goes bad?

Disassemble the lamp and inspect it to find out problems. Then, you should make a replacement for a new one if needed.

How long does ballast last?

According to the Certified Ballast Manufacturers Association, the life expectancy of magnetic and electronic ballasts is approximately 12 to 15 years and up to 20 years, respectively.

Can a fluorescent light work without a ballast?

A fluorescent light may destroy itself quickly by drawing too much electricity if it doesn’t get any help from a ballast due to its own characteristics.

Why don’t LED Lights not need ballast?

As LED lights already have a component called “driver” to control the amount of power input, they do not require a ballast anymore.