WHAT IS A BALLAST?

In the context of an indoor grow room a ballast is a piece of electrical equipment that regulates the voltage that a grow light will receive. If a ballast is not used with lamps such as High Intensity Discharge (HID) types the lamp will continually draw electrical current to an extent that is will overheat and burn out in seconds. 

A ballast will provide enough voltage to the lamp to ignite and then reduce the voltage to the low steady level which is required by the lamp. 

Magnetic ballasts work by using wire and steel. They are made up of a electromagnet housed in a box. The electrical current is channeled into a heavy steel coil and with the aid of capacitors it will reduce and maintain the voltage at the required level. 

Magnetic ballasts are very durable and they are not affected by outside radio inference. 

They still remain the cheapest option when a ballast is required.