### Question
What is the definition of mercury vapor lamp?


### Answer
The definition of **mercury vapor lamp** is as follows in *42 U.S.C. § 6291*:

> a high intensity discharge lamp in which the major portion of the light is produced by radiation from mercury operating at a partial pressure in excess of 100,000 Pa (approximately 1 atm)

#### Citation:
  - *42 U.S.C. § 6291*
  - Heading: **CHAPTER 77-ENERGY CONSERVATION > SUBCHAPTER III-IMPROVING ENERGY EFFICIENCY > Part A-Energy Conservation Program for Consumer Products Other Than Automobiles**

