The two standards of Christmas lights are C9 and C7, with C9 being a larger (5 cm) bulb and C7 (3.5 cm) as a medium-sized bulb, and so on with C6 and C3 bulbs.

Then there’s the size of the bulb, with the most common ranging from the typical strand of mini bulbs, followed by C7 and the larger C9 (roughly 2.25″). First, the math.

Dazzling holiday lights strung over trees, rooftops, gutters and rhododendrons take us back to childhood. Brightly colored lights illuminate the way for evening walks searching the neighborhood for sp ...