Low and high pressure sodium lamps are commonly used for outdoor lighting. They provide light in parking lots, along streets and highways, and in areas where security is important. The lamps also provide indoor lighting in large warehouses.
Color of Light
Low pressure sodium lamps produce a yellow-colored light. This poor color rendition often limits the lamps to outdoor use where the color is not important. High pressure sodium lamps provide slightly better color rendition with a golden to white light.
Low pressure sodium lamps produce more light per watt of energy consumed than high-pressure sodium lamps, which are slightly less efficient.
Low pressure sodium lamps are best used in applications where the light remains on for hours at a time. They take longer to start up than high pressure sodium lamps and must cool down before they can restart.