What is the difference between power factor and ballast factor?

Power Factor:

Power factor (pf) is a measure of how “efficiently” an electrical or electronic product uses its power. It usually expressed as a percentage from 0% to 100%. In a more technical format, power factor is the fraction of power actually used by a customer’s electrical equipment compared to the total power supplied by the utility or the ratio between watts (W) and volt-amperes (VA).

PF= W/VA

Ballast Factor:

Ballast factor (BF) is the ratio of the lumen output of a lamp on commercial ballast (system lumens) as compared to the lumen output of the same lamp on a reference ballast (rated lumens). The reference ballast is set-up and calibrated according to ANSI test procedures (American National Standards Institute). The commercial ballast is a ballast that would be purchased through a ballast manufacturer or store such as an electrical distributor or home improvement warehouse.

BF= (Lumen using commercial ballast)/(Lumen using reference ballast)

Currently, ballast factors range from 0.70 and 1.20. A low ballast factor has a value between 0.70 to 0.80. A normal or “standard” power factor is between 0.85 and 1.00. A high ballast factor is between 1.13 and 1.20. Ballast factor is used in lumen method lighting calculations and is a component of the light loss factors (LLF). Different ballast factors may be used to tailor different spaces in the same building with different light level while using the same lamp thus reducing the risk of using the wrong lamp in the wrong application.