C9 Christmas Light Failures 2005-2006

Not a good year for Denver Bronco's colors.

What is a C9 Bulb?

Christmas lighting began with small C6 bulbs -- C meaning "candle" for the flame shape, and 6 meaning ⁶⁄₈ inches (¾ in, or 19 mm) in diameter. These were on a miniature candelabra screw-base, now designated E10 (Edison screw, 10 mm). Replicas of these bulbs are now produced as miniature strings, usually with the entire bulb replaced, but sometimes as a decorative cover with regular bulbs inside. These bulbs tend to be transparent white or colors, and are often ornately designed with crystal-like patterns.

Later bulbs were called C7½, being 7 1/2 inches (¹⁵⁄₁₆ in, or 24 mm) in diameter; however, these have a blunt shape (and should therefore be called B7½, or B24). Mixing metric and English units, there are also now G30 globes which are 30 mm (1+³⁄₁₆ in, or G9½) in diameter that uses these sockets. These are still used for the classic or even retro look, and use about five watts each. Older bulbs drew 7½ watts of power, and were reduced to save power. Early bulbs, as well as some new antique reproductions, are made in various shapes and then painted like Christmas ornaments. Bubble lights and twinkle bulbs also come in this size.

Outdoor-only bulbs are designated C9¼ (1+⁵⁄₃₂ in, or 29 mm), and have a similar

blunt shape as the C7½, but an E17 "intermediate" base. Some modern versions of these strings are now listed for indoor and outdoor use. These bulbs are rated at about seven watts each, and also now come in a globe shape, designated G40 (40 mm, or 1+⁹⁄₁₆ in). Some of the blunt-shape bulbs now come painted with designs, or swirled in more than one color. It is now very difficult to find twinkle bulbs in this size.