Knowledge Dry Location, Damp Location, Wet Location Lighting

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The U.S National Electric Code (NEC) Article 100 defines dry, damp, and wet locations as follows:

Dry locations:

Location not normally subject to dampness or wetness. A location classified as dry may be temporarily subject to dampness or wetness, as in the case of a building under construction.

Damp locations:

Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture. Examples of such locations include partially protected locations under canopies, marquees, roofed open porches, and like locations, and interior locations subject to moderate degrees of moisture, such as some basements, some barns, and some cold storage warehouses.

Wet location:

Installations underground or in concrete slabs or masonry in direct contact with the earth; in locations subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather.

The UL Standard 1598 defines dry, damp, and wet locations as follows:

Dry Locations:

A location not normally subject to dampness, but may include a location subject to temporary dampness, as in the case of a building under construction, provided ventilation is adequate to prevent an accumulation of moisture.

Damp Locations:

An exterior or interior location that is normally or periodically subject to condensation of moisture in, on, or adjacent to, electrical equipment, and includes partially protected locations.

Wet Locations:

A location in which water or other liquid can drip, splash, or flow on or against electrical equipment. A wet location luminaire shall be constructed to prevent the accumulation of water on live parts, electrical components, or conductors not identified for use in contact with water. A luminaire that permits water to enter the luminaire (during the rain test of Clause 16.5.2 or the sprinkler test of Clause 16.5.3) shall be provided with a drain hole (Clause 13.4.3).

A luminaire marked “SUITABLE FOR WET LOCATIONS” may be additionally marked as specified below:

Covered Ceiling Mount Only — A wet locations luminaire marked “COVERED CEILING MOUNT ONLY” is intended for locations such as a vehicle washing area where the luminaire will not be subjected to water and precipitation from the back side. A ceiling mounted luminaire not identified for covered ceiling mount only is suitable for mounting in locations where it may be subjected to precipitation from the back side, such as under a metal grate-type catwalk.

Less Than 1.2 M (4 Feet) Above Ground Level — A wet locations wall or post mounted luminaire may be installed within 1.2 m (4 feet) of ground level if it is marked “SUITABLE FOR MOUNTING WITHIN 1.2 M (4 FEET) OF GROUND.” luminaires with this marking are intended to be subjected to water from lawn and garden sprinkler systems, but are not intended to be installed at or below ground level where they may be subjected to immersion in water.

Exception: A luminaire with an integral post (bollard type luminaire) needs to be so marked.

Below Ground Level — A wet locations recessed luminaire may be installed at or below ground level if it’s marked “SUITABLE FOR GROUND-MOUNTED RECESSED.” A luminaire with this marking is intended to be subjected to infrequent immersion under water which may occur because of heavy precipitation. The luminaire is provided with instructions for its proper installation.