BT and TB bulbs refer to two different types of light bulbs, primarily distinguished by their shapes and applications. Here's a breakdown of each:

BT Bulbs (Bulged Tubular):

  • Shape and Design: BT bulbs are known for their rounded or bulbous shape. They are typically more spherical or have a slight bulge in the middle, which gives them their distinctive appearance.
  • Uses: These bulbs are often used in decorative lighting applications, such as chandeliers, pendant lights, and some types of lamps where the bulb's appearance is as important as its functionality. They can also be used in some standard household fixtures.
  • Sizes: BT bulbs come in various sizes, such as BT15, BT19, BT20, etc. The number following "BT" generally indicates the diameter of the bulb in eighths of an inch (e.g., a BT15 bulb has a diameter of 15/8 inches or about 1.875 inches).
  • Types: They can be found in different types, including incandescent, CFL (compact fluorescent), and LED.

TB Bulbs (Tubular):

  • Shape and Design: TB bulbs are more elongated and tubular in shape, often looking like a long, thin cylinder. They can be straight or slightly bent.
  • Uses: These bulbs are commonly used in fixtures where space is limited or where a more directed light is needed. They are frequently seen in under-cabinet lighting, task lighting, and some types of linear fixtures.
  • Sizes: TB bulbs also come in various sizes. For instance, TB8, and T12 are common designations that refer to the bulb's diameter in eighths of an inch (e.g., a T8 bulb has a diameter of 8/8 inches or 1 inch).
  • Types: Like BT bulbs, TB bulbs are available in incandescent, fluorescent, and LED varieties.