Standard fluorescent bulb sizes are typically defined by their diameter, with common sizes including T12, T8, and T5. These designations represent the bulb's diameter in eighths of an inch.
Here's a breakdown of common fluorescent bulb sizes:
- T12: These are 12/8 inches, or 1.5 inches (38 mm) in diameter. They are generally older and less energy-efficient.
- T8: These are 8/8 inches, or 1 inch (25 mm) in diameter. T8 bulbs are a common and more energy-efficient alternative to T12.
- T5: These are 5/8 inches, or 0.625 inches (16 mm) in diameter. T5 bulbs are typically smaller and more energy-efficient than T8 and T12, often used in specialized fixtures and some battery-powered devices.
While T12, T8, and T5 are the most prevalent, you might also encounter:
- T10: 10/8 inches or 1.25 inches in diameter
- T17: 17/8 inches, or 2+1/8 inches in diameter. Often found in older fixtures.
- Compact Fluorescent Lamps (CFLs): These bulbs come in various shapes and sizes, effectively replacing incandescent bulbs in many applications. They do not conform to the "T" naming convention.
- T4: (1/2 inch in diameter) Less common in general lighting, used in specialized applications.
It is important to note that the 'T' number refers to the bulb's diameter and does not indicate the bulb's length, which can vary significantly.
| Bulb Type | Diameter (inches) | Diameter (mm) | Notes |
|---|---|---|---|
| T12 | 1.5 | 38 | Older, less efficient |
| T10 | 1.25 | 31.75 | Less Common |
| T8 | 1 | 25 | Common, energy-efficient |
| T5 | 0.625 | 16 | Smaller, energy-efficient, specialized uses |
| T4 | 0.5 | 12.7 | Specialized applications |
In summary, standard fluorescent bulb sizes primarily revolve around T12, T8, and T5, each corresponding to a specific diameter in eighths of an inch. Newer fixtures typically use T8 or T5 bulbs due to their increased energy efficiency.
