Digital vs. Magnetic for HID Lighting

Selecting the right lighting equipment for your grow operations can be tricky. Therefore, we're starting a series of posts on lighting and related equipment. We start by looking at ballast. 

What is a ballast?

A ballast is the power supply for your grow lamp.  It takes outlet voltage, boosts it for start up, then regulates that voltage to maintain the arc inside your grow lamp.  Both HPS and MH lamps require the use of a ballast.

Magnetic ballast

Magnetic ballasts are constructed of steel sheets wrapped in a spool of wire. These components make a magnetic ballast considerable in weight, up to 50lbs. They are considered “tried and true” technology and have been around for many years.  They are very durable easily serviced and last for years, even in adverse conditions.  

The cost of magnetic ballasts is also about half that of a digital ballast.  The down side of a magnetic ballast is they are lamp and wattage specific. A 600w HPS ballast cannot run a 400w bulb nor can it run a MH bulb, although there are some switchable ballasts that can run either HPS or MH, but even these are still wattage specific.  Another drawback of these ballasts is the production of significant heat and an audible hum both of which increase as the ballast ages.

Digital  ballast

A digital ballast contains small semiconductors and microprocessors to start and regulate voltage to the lamp.  The advantages of a digital ballast are many. They are much lighter weighing in around 10lbs.

Image credit: https://hydroponics.com

Most  can run a HPS or MH lamp in a range of wattages.  Digital ballasts do not hum and produce significantly less heat.  They regulate voltage to the lamp more precisely and eliminate flicker. Many also use soft start technology that is much easier  on the lamp and extends the life of the bulb.  They have the ability to fully fire the lamp producing as much as 30 percent more light from the same bulb as compared to a magnetic ballast. These ballasts can also sense that a bulb is bad and will not try to fire it.  They will also not try to ignite a bulb after a power blip until the bulb has cooled enough to do so, preventing damage to the bulb.

The biggest disadvantage to the digital ballast is cost, which is at least double that of a magnetic ballast and varies widely by brand.  One last consideration is some digital ballasts cause RF interference and disrupt radio and TV reception.

If you have questions on what might be best for you, hit us up anytime!