May 25, 2017

UL 1598 Standard for Safety – Luminaires defines three moisture protection types for luminaires, Dry, Damp or Wet.

Type Definition
Dry 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 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 A location in which water or other liquid can drip, splash, or flow on or against electrical equipment.


Interior luminaires are often listed as dry or damp and most exterior luminaires are listed as wet. However, there are national and local requirements for interior luminaires to be wet location listed in areas such as bathrooms and above showers.

DMF Lighting offers several luminaires, such as the DRDH/DRD2M/DRD2T, that are UL 1598 Standard for Safety ā€“ Luminaires tested and marked ā€œSuitable for Wet Locationā€. The DRD2M module must be installed with a DRD2T trim with our signature Twist & Lock feature to qualify for the wet location designation.

Up to the Test

The UL 1598 Standard specifies three wet location tests that can be applied to a luminaireĀ depending on its usage and mounting location: rain, sprinkler or immersion. A given luminaireĀ can be subject to one or more tests to determine if it can be classified as wet location. All the tests attempt to simulate what the luminaire is likely to undergo in the environment it is intended to be used.

The DRDH/DRD2M/DRD2T luminaire is a recessed downlight used in ceilings that are protected from external moisture. This means that the application prevents moisture penetrating from above. To this end, the DRDH/DRD2M/DRD2T luminaire was tested using the sprinkler test. The test is arduous and is conducted with the controlled spray head pointing at the luminaire while set to 20 psi3.


The test is performed over four hours and is sequenced as follows:

  • First hour ā€“ luminaire is turned on and water jet is off
  • Next half hour ā€“ luminaire is turned off and water jet is on
  • Next two hours ā€“ luminaire is turned on and water jet is on
  • Last half hour ā€“ luminaire is off and water jet is on

After the test is complete, the luminaire is subjected to a dielectric voltage withstand test andĀ fully inspected to make sure that no water intrusion occurred that could cause a hazard or theĀ luminaire to malfunction.

Technical Bulletin: Wet Location Luminaires