Environmental Type ratings Table 6.1, UL 50
The enclosure environmental ratings and the corresponding requirements are as follows. Please note that these rating types are not equivalent to the IP Codes used for international evaluations as described in IEC 529.
| Type | Intended use and description | Requirements or qualification tests, paragraph or section numbers |
| 1 | Indoor use primarily to provide a degree of protection against limited amounts of falling dirt. | Corrosion Protection -- 5.3 or Rust Resistance - Section 38 |
| 2 | Indoor use primarily to provide a degree of protection against limited amounts of falling water and dirt. | Corrosion Protection -- 5.3 or Rust Resistance -- Section 38, Drip -- Section 31, Gaskets -- Section 14, and Gasket Tests -- Section 43 |
| 3 | Outdoor use primarily to provide a degree of protection against rain, sleet, wind blown dust and damage from external ice formation. | Rain -- Section 30, Outdoor Dust or Hose -- Section 32 or 35, Icing -- Section 34, Protective Coating -- Section 15, Gaskets -- Section 14, and Gasket Tests -- Section 43 |
| 3R | Outdoor use primarily to provide a degree of protection against rain, sleet, and damage from external ice formation. | Rain -- Section 30, Icing -- Section 34, Protective Coating -- Section 15, Gaskets -- Section 14, and Gasket Tests -- Section 43 |
| 3S | Outdoor use primarily to provide a degree of protection against rain, sleet, windblown dust and to provide for operation of external mechanisms when ice laden. | Rain -- Section 30, Outdoor Dust or Hose -- Section 32 or 35, Icing -- Section 34, Protective Coating -- Section 15, Gaskets -- Section 14, and Gasket Tests -- Section 43 |
| 4 | Indoor or outdoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, hose-directed water and damage from external ice formation. | Hosedown -- Section 35, Protective Coating -- Section 15, Icing -- Section 34, Gaskets -- Section 14, and Gasket Tests -- Section 43 |
| 4X | Indoor or outdoor use primarily to provide a degree of protection against corrosion, windblown dust and rain, splashing water, hose-directed water, and damage from external ice formation. | Hosedown -- Section 35, Protective Coating -- Section 15, Corrosion Resistance -- Section 39, Icing -- Section 34, Gaskets -- Section 14, and Gasket Tests -- Section 43 |
| 5 | Indoor use primarily to provide a degree of protection against settling airborne dust, falling dirt, and dripping noncorrosive liquids. | Corrosion Protection -- 5.3 or Rust Resistance -- Section 38, Drip -- Section 31, Indoor Settling Airborne Dust or Atomized Water Method B -- Section 32 or 33, Gaskets -- Section 14, and Gasket Tests -- Section 43 |
| 6 | Indoor or outdoor use primarily to provide a degree of protection against hose-directed water, and the entry of water during occasional temporary submersion at a limited depth and damage from external ice formation. | Hosedown -- Section 35, Icing -- Section 34, Submersion -- Section 36, Protective Coating -- Section 15, Gaskets -- Section 14, and Gasket Tests -- Section 43 |
| 6P | Indoor or outdoor use primarily to provide a degree of protection against hose-directed water, the entry of water during prolonged submersion at a limited depth and damage from external ice formation. | Hosedown -- Section 35, Icing -- Section 34, Protective Coating -- Section 15, Air Pressure -- Section 40, Gaskets -- Section 14, and Gasket Tests -- Section 43 |
| 12, 12K | Indoor use primarily to provide a degree of protection against circulating dust, falling dirt, and dripping noncorrosive liquids. | Corrosion Protection -- 5.3 or Rust Resistance -- Section 38, Drip -- Section 31, Indoor Circulating Airborne Dust or Atomized Water Method A -- Section 32 or 33, Gaskets -- Section 14, and Gasket Tests -- Section 43 |
| 13 | Indoor use primarily to provide a degree of protection against dust, spraying of water, oil, and noncorrosive coolant. | Corrosion Protection -- 5.3 or Rust Resistance -- Section 38, Oil -- Section 37, Gaskets -- Section 14, and Gasket Tests -- Section 43 |
