Medium-intensity white strobes are usually used on structures that are between 200 and 500 feet (61-152.4 meters). If a medium white strobe is used on a structure greater than 500 feet (152.4 meters), the structure must be painted. The common medium white strobe flashes 40 times per minute, at an intensity of 20,000 candelas for daytime/twilight, and 2,000 candelas at nighttime.