Burn Base Up. A designation specifying that the lamp should be operated with the bottom (base) of the lamp above the filament. Non- tungsten-halogen lamps were particularly finicky about orientation, due to how the coils of the filament were supported.

There is usually a number following, giving maximum deviation from vertical. Thus BBU45 (or BU45) means base up +/- 45 degrees. The BBU lamp was/is used in the radial ERS, and is in fact the reason for the lamp penetrating the reflector in a non-axial location. With the fixture above and pointing 45° downward, the lamp is vertical.

For the opposite, see BBD.

With today's modern lamps, it's an unnecessary specification, as almost all T/H lamps allow "burn in any position."

This page has been seen 508 times.

Industry Advertising

Recent Activity

Readability Information

An automated review of this page attempts to determine its readability in English (US). The page contains roughly 121 words across 9 sentences.
Readability score
Readability score: 44.26
Grade level
For the information in this page to be accessible to the widest audience of readers, both a high readability score and a low grade level are ideal.

Icon Legend

  • Normal page
  • Color code

    • Content has new updates
    • Content has no updates

CB Advertising

Sign up to Advertise Today