Robertson 21300 HP21327SP-V4 Compact Fluorescent Ballast at eLightBulbs.com

Lumens (light output)

This refers to the literal measure of the light-output of a particular light bulb, measured in the number of lumens.

Watts (Energy Used)

"Watts" is the term applied to the amount of energy required and used by a particular light bulb. It is an international system unit of power equal to one joule per second. Contrary to popular belief, the wattage of a bulb does not directly measure the brightness; the "lumens" of a light is what defines the actual light output.

Average Lifetime

This refers to an average lifetime rating based on large quantities in test groups. This testing takes into account usage of 3 hours per start for fluorescent lamps and 10 hours per start for HID lamps.

Volts

Voltage is a measure of electrical potential.

Bulb Type

The "Bulb Type" is typically a combination of the style of bulb as well as the width of the bulb. Usually, the first couple letters will indicate the type; "G" would indicate "Globe", "PAR" would indicate "Parabolic Reflector"... The numbers indicate the diameter of the light bulb in eighths of an inch; a "G40" would be a "Globe" style that is "5 inches" in diameter.

Fluorescent Ballasts > Compact (CFL) > Robertson 21300 (HP21327SP-V4)

2 Lamp 277 volt HPF Electromagnetic Compact Fluorescent Robertson Ballast

Robertson 21300
HP21327SP-V4

Fluorescent Ballasts > Compact (CFL) > Robertson 21300 (HP21327SP-V4)

2 Lamp 277 volt HPF Electromagnetic Compact Fluorescent Robertson Ballast

Robertson 21300HP21327SP-V4

Robertson 21300
HP21327SP-V4