Contributed by: Flowerman
Yes Ballasts and Bulbs Should be Matched.
HID bulbs generally need specific ballasts, and any given ballast
can usually safely and effectively operate only one type or a few types
of HID bulbs.
The bulb wattage must be matched to the ballast. A smaller bulb
will usually be fed a wattage close to what the proper bulb takes, and
will generally overheat and may catastrophically fail. Any catastrophic
failures may not necessarily happen quickly. A larger bulb will be
underpowered, and will operate at reduced efficiency and may have a
shortened lifetime. The ballast may also overheat from prolonged
operation with an oversized bulb that fails to warm.
Even if the ballast and bulb wattages match, substitutions can be
limited by various factors including but not limited to different
operating voltages for different bulbs. Examples are:
Pulse-start sodium lamps often have a slightly lower operating
voltage than metal halide and mercury lamps of the same wattage, and
ballasts for these sodium bulbs provide slightly more current than
mercury and metal halide ballasts for the same wattage would. The
higher current provided by the pulse-start sodium ballast can overheat
mercury and metal halide lamps. Mercury and metal halide lamps may also
"cycle" on and off in lower voltage sodium ballasts, such as many 50 to
100 watt ones.
Metal halide lamps have an operating voltage close to that of
mercury lamps in many wattages, but have stricter tolerances for
wattage and current waveform. Metal halides also usually need a higher
starting voltage. Most metal halide lamps 100 watts or smaller require
a high voltage starting pulse around or even over 1,000 volts.
175 to 400 watt metal halide lamp ballasts can power mercury lamps of the same wattage, but the reverse is not recommended.
Mercury lamps 50 to 100 watts will work on metal halide ballasts,
but hot re-striking of mercury lamps 100 watts or smaller on metal
halide lamps may be hard on the mercury lamp since the starting pulse
can force current through cold electrodes and the starting resistor
inside the mercury lamp.
1,000 watt mercury lamps come in two operating voltages, one of
which is OK for 1,000 watt metal halide ballasts. A few wattages of
pulse-start sodium (150 watts?) come in two voltages.
A low voltage lamp in a high voltage ballast will be underpowered,
resulting in reduced efficiency, possible reduced lamp life, and
possible ballast overheating. A high voltage lamp in a low voltage
ballast will usually cycle on and off, operate erratically, or possibly
overheat. This will usually result in greatly reduced lamp life in any
One class of sodium lamps is made to work in mercury fixtures, but these only work properly with some mercury ballasts, namely:
'Reactor' (plain inductor) ballasts on 230 to 277 volt lines.
'High leakage reactance autotransformer' ballasts, preferably with
an open circuit voltage around 230 to 277 volts. NOT 'lead',
'lead-peak' nor any metal halide ballast!
These sodium lamps may suffer poor power regulation and accelerated
aging in the wrong mercury ballasts, especially after some normal aging
changes their electrical characteristics. Also, these lamps may
overheat and will probably have shortened life with pulse-start sodium
Many sodium lamps require a high voltage starting pulse provided only by ballasts made to power such lamps.
To prevent dangerous accidents please keep remote ballasts away
from tap points and on an elevated position (approx 5 inches off the
floor) using a block or shelf.