As their name implies, high-bay lights are used to illuminate spaces with high ceilings. That usually means ceilings ranging from 20 feet to approximately 45 feet. Because a high-ceiling location has more space to fill, a high-bay by definition is a powerful light source that can brighten up a large area. Bay lights are light fixtures with high power wattage requirements. More often than not, bay lights are installed in ceilings over 12 feet in height and produce over 8000 lumens.