Lamps must be used in their specified operating positions in order to maximize lamp performance and longevity. Incorrect operating positions may also create the possibility of a lamp rupture.

It is imperative that users adhere to the specified operating positions and fixture requirements. The following chart shows the correct lamp operating positions based on the Position Code Letters. These letters are always presented in the lamp description.

Fixture Requirement Codes

  • O = Open fixture permissible. Lamps can be operated in an open fixture within the lamp’s specified operating position limits.
  • S = Open fixture permissible with operating position restrictions.
  • E = Enclosed fixture required. Lamps must be operated in an enclosed fixture.

Lamp Operating Position Codes and Symbols

U or No Code

Universal (no limit)


Base Up ±15°


Vertical ±15 Base Up or Base Down

BUD ±60

Base Up or Base Down ±60


Base Up to Horizontal

HOR ±15°

Horizontal ±15°

HOR ±30

Horizontal ±30°

HOR ±45

Horizontal ±45°

HOR ±60

Horizontal ±60°