On a dimmable ballast it is by way of a dial.
This image shows the dial on a 600 watt dimmable ballast.
600SL - 600 watt Super Lumen setting
600W - 600 watt 'normal' setting.
400SL - 400 watt Super Lumen setting, or a 'dimmed' 600 watt setting
400W - 400 watt 'normal' setting, or a further 'dimmed' 600 watt setting.
On other models, 'Super Lumen' is activated by the toggle switch.
On ( I ) - Super Lumen has been activated.
Off ( O ) - The ballast is running in normal mode.
The Super Lumen setting should only be used with HPS lamps. It should never be used when using Metal Halide lamps, and will cause damage to the lamp.
The Super Lumen switch/dial can be operated while the ballast is in operation, but must be left operating for 10 minutes before changing to another setting. Changing the Super Lumen setting sooner than this will result in reduced lamp life
