Ballast Heat: Electronic ballasts are designed to operate in ambient temperatures less than 105 degrees F. The inside or core temperature of the ballast is not to exceed 75 degrees C. Magnetic ballasts have a maximum core temperature of 90 degrees C. It is important to remember that electronic ballasts are more heat sensitive than magnetic ballasts as indicated by the lower maximum core temperature.

Thermal Cycle: If the ballast inside or core temperature rises above the maximum, (75 degrees C), then the ballast will activate a thermal cutoff device to prevent permanent damage. This excessive heat can be due to the way the ballast is mounted in the fixture, or conditions in the area where the ballast is in use. If the conditions causing excessive heat are not corrected the ballast will operate until overheated and then shut itself off until cool. The ballast will then automatically repeat this cycle over and over. This is known as thermal cycling. If a ballast is left in this condition for an extended period of time the excessive heat will cause the ballast to fail.

Cold Temperature: Colder ambient temperatures make fluorescent lamps harder to start. Cold temperatures do not effect ballast performance. The problem of starting a fluorescent lamp in cold temperature relates strictly to the particular characteristics of the lamp in use. Reducing the amount of mercury in a fluorescent lamp makes a lamp harder to start in cold temperatures. Energy Saver or reduced wattage lamps contain less mercury. Energy Saver or reduced wattage lamps generally require 60 degrees F for reliable starting regardless of which ballast is used.

Shunted Sockets: With the new T8 lamps we now have a bi-pin lamp that can be instant or rapid started. Shunted sockets connect the two pins on one lamp end together to prevent damage to the filament when using an instant start ballast. This eliminates the need to install wire jumpers, and makes for easier wiring of the fixture. It is important to remember that shunted sockets are for use with instant start ballasts only. Operating a rapid start ballast on a fixture with shunted sockets will damage the rapid start ballast.

Ballast Factor: This is the ratio of the light output of an ANSI standard reactor (ballast) to the light ouput of the ballast being rated for ballast factor. In simpler terms, simply multiply the Ballast Factor times the rated lumens of the lamp to get the light output of the lamp/ballast combination.

Ballast Efficacy Factor: Measure of relative light delivered per watt consumed by a specific lamp/ballast combination.

Crest Factor: This is the ratio of the peak starting current to the operating current of a ballast. Generally ballasts are designed to have a crest factor less than 1.7 to insure normal lamp life. Using a lamp listed on the ballast label insures that the lamp/ballast combination have been tested and will not cause excessive crest factor when started.

OCV: Open Circuit Voltage. This is the high voltage supplied by the balllast to the lamp at start up. This voltage is required to initiate the arc in the lamp. After the lamp arc is established and current begins to flow, the voltage across the lamp will gradually lower as the lamp heats up. The voltage will stabilize at the Arc Voltage or Operating Voltage of the lamp.

Input Watts: This is the combined power used by the lamp/ballast combination.

Power Factor: This is a measure of the Actual Power divided by the Apparent Power. Also expressed as a percentage, a high power factor ballast has above 90 percent Power Factor. The lower the power factor, the higher the current per watt required to operate the device. The total input power remains the same. An advantage of High Power Factor is that more devices can be used on the same size branch circuit if they have a high power factor.

Harmonic Distortion: Distortion of the supply line current (or voltage) created by non-linear loads including but not limited to all types of arc discharge lighting.

Standard Electromagnetic Ballast: Basic autotransformer technology utilizing the least cost (high core loss) materials (iron and aluminum).

Energy Saving Electromagnetic Ballast: Functionally the same as a standard ballast but utilizing premium (low core loss) materials (steel and copper).