Ballasts

A grow light ballast strikes your CMH or HID lamp, then holds its current steady so the lamp runs at its rated wattage. Pick the PLS 315W for single CMH lamps, the EnergyStation kit for 945W CMH with an HPS option, and the adapter to mix brands.

3 products

Ballasts

Grow Light Ballasts for CMH and HID Lamps

A grow light ballast starts an HID or CMH lamp with a high-voltage strike, then holds the current steady while it runs. This collection carries a Prism Lighting Science 315W CMH ballast, a 945W CMH lamp and ballast kit, and a plug adapter. Compare ballast output in our best 1000 watt ballast test....

Grow light ballast infographic: CMH and HID ballast types, lamp matching, remote mounting, voltage and what a ballast does

A ballast has to match its lamp in type and wattage, so pick replacement lamps from our MH, HPS and CMH bulbs. Complete fixtures with a built-in ballast sit in the wider grow lights range.

Types of Ballasts

CMH Remote Ballasts

The Prism Lighting Science 315W ballast runs one 315W CMH lamp on a low-frequency square wave tuned to Philips CDM bulbs. It takes 120 to 240V, mounts outside the canopy to keep heat out of the room, and carries five protections and a 3-year warranty.

Lamp and Ballast Kits

The AllState EnergyStation kit pairs a 945W double ended CMH lamp at 3200K with a matched 240V ballast. The ballast can also fire a 1000W HPS lamp for an HPS finish, so one unit covers a CMH grow and a sodium flower.

Adapters

The Hydrofarm plug adapter connects a Hydrofarm ballast to a Brand S reflector or cord set. It lets you mix older Hydrofarm ballasts with standard reflectors without rewiring either one.

How Growers Use Ballasts

Match the ballast to the lamp type and wattage first, then to your circuit: the 945W kit needs a 240V line. Mount remote ballasts outside the tent or room so their heat stays out of the canopy. Keep them off the floor and away from water.

Frequently Asked Questions

What is a light ballast?

It is the power unit between the outlet and an HID or CMH lamp. It sends a high-voltage pulse to strike the arc, then limits current so the lamp runs at its rated wattage. Each ballast suits a lamp type and wattage, like the PLS unit, built for 315W CMH only.

What is a digital ballast?

A digital ballast uses electronics instead of a heavy magnetic core to drive the lamp. In our own 1000W test under one HPS lamp, the best digital model gave PAR readings about 39% higher than a magnetic ballast. Digital units are also lighter and often dimmable.

Do LED grow lights need a ballast?

No. LED fixtures run on drivers, which are built in or mounted remotely, so they never use an HID ballast. Ballasts are only for HID and CMH lamps such as metal halide, high pressure sodium and ceramic metal halide. Keep a ballast if you still run those lamps.