October 23, 2017
In addition to UL ratings that are tested and rated by Underwriters Laboratories (UL), an independent product safety certification organization, IP ratings are given to fixtures after rigorous laboratory testing. Anything from lighting to mobile phones are tested for ingress protection. Fixtures are rated on how impervious their surfaces are to solid and liquid, from fingers and small drops of water to fine dust and full submergence.
A damp location is an exterior or interior location that is normally or periodically subject to condensation of moisture in, on or adjacent to the electrical components of a lighting fixture or ceiling fan.
Indoor Damp Locations include indoor pool areas, utility rooms and over bathtubs or showers in bathrooms (without risk of direct water contact).
Outdoor damp rated fixtures can only be used in covered, fully protected locations that are not directly exposed to water, even during storms.
Outdoor Damp Locations include covered patios and covered porches that are fully protected from water, even during storms.
Only lighting and fans marked "Suitable for Wet Locations" can be used in wet locations, both indoors and outdoors. A wet location is an interior or exterior location in which water or other liquids may drip, splash or flow on or against the electrical components of a lighting fixture or ceiling fan. Outdoor Wet Locations include open-air decks and patios, uncovered porches, outdoor dining areas, exterior walls, gazebos, pergolas and walkways. Indoor Wet Locations include shower enclosures.
(text from Lumens.com)