Lighting systems for indoor growing include a ballast, which is the component of the electrical system that regulates the voltage that each lamp receives. Without a ballast, the bulbs would uncontrollably extract so much current from the available electrical source that they could end up overheating and burning in seconds.
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Most indoor growers know that a grow lamp cannot work without a ballast, but many don't exactly know what this means. To understand the job of the ballast, it's important to first learn how a grow lamp works.
What is a light ballast?
Compact fluorescent lamps (CFL) or High-intensity discharge lamps (HID), whether Mercury-vapour, Metal-halide (MH), or High-pressure sodium (HPS), essentially use two components to provide light: an electric arc and a gaseous mixture (generally using material in a solid state, such as sodium.) Electricity provides the bulb with enough voltage for the electric arc to turn the solid into gas, thereby producing light.
Once the solid turns into gas, the bulb doesn't need as much electricity to stay on, because the resistance of the lamp decreases when the material is in a gaseous state, so less energy is required for the lamp to keep working.
This means that at that point the voltage that the bulb receives needs to be reduced. This is the job of the ballast: it helps adjust the electric arc and maintains a constant current flow, which prevents the lamp from burning and provides a uniform, stable, and flicker-free light spectrum. If you didn't have a ballast in your lighting system, you would either be providing your lamp with too much electricity so it would end up burning out, or the electricity flow wouldn't be strong enough to transform the solid material into the gas that produces the light.
Magnetic or electronic ballast?
There are basically two types of ballast: magnetic and electronic.
Magnetic ballasts are made up of a series of copper coils wrapped around metal connectors. When they're plugged in, ballasts send energy through the coils to regulate the amount of light that the bulb needs. All these components heat up considerably, so they need constant cooling in order to keep the lights, cannabis plants and grow room protected from extreme heat. Many marijuana growers prefer magnetic ballasts because they're cheaper, but they're not ideal as they disperse a lot of thermal energy.
On the other hand, electronic ballasts are made up of a series of semiconductors and electronic components (rather than copper coils and metal connectors) that regulate the voltage that the bulb receives. These elements also heat up, but thanks to their reduced size, most if not all electronic ballasts feature internal fans that keep them cool whilst they're working, as with computers. In addition, electronic ballasts don't produce vibrations or the typical flickering associated with magnetic ballasts.
Some electronic ballasts are labelled as 'digital ballasts'. This means that they include a microprocessor. The main advantage of the digital type is that they can perform the same functions as standard electronic ballasts whilst offering higher accuracy. Digital ballasts can also be adjusted at any point between 400 and 1000 watts. However, they are the most expensive type of ballast currently on the market.
What does ballast power mean?
Each ballast has a specific power output, which needs to be in accordance with the power that the bulb can withstand. Some ballasts include a voltage regulator, whereas others only feature a single output voltage.
Most ballasts work with a 175-275V power supply. Some commercial models can also work with 220V, 347V, 400V and 480V. Ballasts with a fixed voltage can be used in grow spaces or in rooms for mother plants, where lights are always on.
On the contrary, adjustable ballasts can be used in grow rooms or tents for the full life cycle of the plants, as the output power can be regulated to 50, 75, 100 or 110%, depending on the amount of light that the plants need at every stage of growth. For instance, power can be set at 75% during the growth phase, 100% during the bloom phase, and even at 110% at the bud fattening stage.
Cannabis growers normally use a ballast with a 600W power output, that can be adjusted to 250W, 400W, 440W and 660W, depending on the model. There are also some 1000W ballasts with a power controller with 4 different configurations: 600W, 750W, 1000W, and 1000W SL ('Super Lumens' option, designed to promote bud density.)
Can I use a ballast with an LEC lamp?
LEC (Light Emitting Ceramic) lamps are a new technology that is becoming increasingly popular in indoor cultivation. They are an evolution of the CMH (Ceramic Metal Halide) lighting systems. LEC lamps have a power of 315W, 630W, or 945W, which makes them difficult to combine with a ballast that is not specifically designed to work with this type of bulb. But you can already find a good range of LEC-specific ballasts on the market.
Do LED lamps require a ballast?
LED lights work differently and only need a continuous current, so they can be connected directly to a standard power supply, without the need for a ballast. When you use LED lights to grow cannabis, all you need is already included within the lamp housing itself, so an additional component like a ballast is not required.
Remember that magnetic ballasts can create excess heat as they are the main heat producers when you're using HID lamps. So keeping the ballast out of the grow space helps control its temperature. Ballasts should always be in well-ventilated areas and should never be covered. Make sure they're always kept clean too, as fluff and dust build-up can lead to fires.