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Magnetic vs. Digital Ballasts

What is a Ballast?

digital grow light and ballast

The ballast is a power supply for arc discharge lamps. It contains the necessary electronics and controls that make the light work.  Its purpose is to provide the lamp with high voltage during start-up, and then to stabilize the arc by limiting the electrical current to the lamp during operation. All fluorescent and high intensity discharge (HID) lamp types require the use of a ballast. If electrical current were to flow into the light bulb at full voltage, the bulb would burst, so the controlling factor offered by the ballast is necessary for the correct function of any fluorescent or HID light.

What is the Difference Between Digital & Magnetic Ballasts?

Magnetic ballasts consist of one or more aluminum or copper coils that sit on a core that is made up of steel laminations. A transformer works in conjunction with a capacitor, and sometimes an igniter. These three parts are most often built into the ballast casing. Digital ballasts are a type of electrical ballast that regulates the amount of electric current in a device. These types of ballasts use microprocessors to control the electric current so it can be regulated through the use of firmware installed in the microprocessor.


There are many advantages that digital ballasts have over their magnetic counterparts. They are more efficient, quieter, cooler, and softer on the bulb than magnetic ballasts. Digital ballasts also weigh less, which is an important consideration in a greenhouse setting.  Because of the more consistent application of electrical current, lamps also last longer and function at a higher level with a digital ballast, and produce a more consistent. Magnetic ballasts, especially as they age, become noisier when they operate, cause the HID lamps to flicker and also contribute to irregularities in the color that the lamp gives off. The digital units can also sense when the lamp is almost used up, and can shut the unit off when it is not functioning optimally.

How Do You Determine Which Ballast To Use?

There are many types of ballasts available, and the specific type you will need depends on the HID lamp’s wattage and type you decide to use. Different ballasts are available for each specific style of grow lights, and each ballast offers different advantages regarding efficiency, longevity, color stability, and brightness.


There are two types of HID lights commonly used in indoor gardens, which includes metal halide (MH) and high-pressure sodium (HPS) lamps. Metal halide lamps are typically used during the vegetative stage, while high-pressure sodium lamps are used during the flowering stage to mimic the harvest sun. For best results, use both MH and HPS lights throughout the lifecycle of the plant.


Your first choice to determine which type of light to use, as well as the wattage. Typical HID lamps are available in 150-watt, 175-watt, 250-watt, 400-watt, 600-watt and 1000-watt versions. The ones most commonly used for indoor gardens are the 400-watt, 600-watt, and 1000-watt configurations. Generally speaking, for lamps with similar color temperatures, the higher the lamp’s wattage, the more light it produces.


Once the lamp has been determined, the next step is to determine the appropriate ballast. When putting together an HID lighting system, it is very important to match the ballast to the lamp(s). In general, any ballast rated for the lamp it is designed for will function properly, though some will perform better than others. For example, GGL ballasts feature the best components on the market, and can be used with both metal halide and high pressure sodium bulbs. These tried and true lighting systems integrate the latest technology and have an amazing warranty ranging from three to five years for all of their products.

Spotlight on Global Greenhouse Lighting (GGL) Ballasts

global greenhouse lighting logo

Combining state of the art lighting science, premium components and vigorous testing methods, Global Greenhouse Lighting (GGL) produces some of the best digital ballasts on the market today. GGL products are made with the best and most reliable components available, and their incredibly quiet ballasts are highly efficient, producing very little heat. GGL ballasts also fire the bulb brighter, providing more lumen output than a standard magnetic ballast. This is because GGL ballasts fire at a higher frequency, minimizing the wear and increasing lamp life by 3 to 4 times.


GGL Ballast Benefits:

  • 3 year manufacturer’s warranty
  • Fires both HPS and MH lamps
  • 15% – 20% more lumen output
  • Higher efficiency means very little heat
  • Works with any socket, reflector, or lamp on the market
  • Light weight with built in mounting bracket
  • Generator Friendly
  • Includes a 120v/240V power cord.

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One thought on “Magnetic vs. Digital Ballasts

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