Agriculture Reference
In-Depth Information
FIGURE 3.6
Vertizontal reflector, 4-foot diameter for HID lamps. (Courtesy of
Sunlight Supply, Inc., Vancouver, Washington.)
BALLASTS
To reduce heat buildup near the location of the lights, install the ballasts
some distance away from your growing area. Keep them up off the floor
in an area free of splashing water and where they will not fall. Connect
the ballast into a timer so that you can set the hours of lighting to come on
automatically. It takes up to 30 seconds for the bulb to ignite and up to 5
minutes for it to become fully bright. During the warm-up period the light
may flicker.
When a MH light is turned off it requires 15 to 20 minutes to cool down.
Do not restart it during this cooling period, as that will reduce the longev-
ity of the bulb. Metal halide lights should be replaced every year. HPS
lamps need only several minutes to cool. They should be replaced every
few years. Prices of ballasts are from $200 to almost $400 depending upon
the power and whether they are single or dual fixture (Figure 3.7). Variable
watt ballasts that operate 400-, 600-, and 1000-watt bulbs are available at
the higher price level. The 1500-watt ballasts usually operate on 240 volts
and cost close to $500. Ballasts are not required for compact fluorescent
or LED lights. These lights also give instant illumination on startup. The
compact fluorescent and LED lights have the great advantage of lasting for
many years compared to the MH or HPS lamps.
LIGHT MOVERS
Light can be more evenly distributed over the plant canopy with some
form of moving the lights. Light movers will also help to prevent burning
