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Electrical Enclosure Ratings Overview

The majority of electrical enclosure testing is conducted to one of four ingress protection test standards. The first is IEC 60529. The second is NEMA 250 and the third and fourth are UL 50 and UL 50E. Each of these testing standards has a definition of protection. NEMA 250 and the UL standards also outline design requirements. This page covers both the Electrical Enclosure Ingress Protection Requirements as well as the Electrical Enclosure Design Requirements.

Ingress Protection Requirements of Electrical Enclosures

IEC 60529 ingress protection testing is also called IP Code testing. The testing focuses on the degree of protection an enclosure provides against solids and liquids. The IP Code is a two-number combination. The first number is the degree of protection from solid objects. The second number is the degree of protection from liquids. The chart below shows the IP Code ratings.

IP RatingSize of Object Protected AgainstExamples of Objects Protected Against
IP 0XNo protectionNone
IP 1X> 50 mmLarge surface of body, but not deliberate contact (back of hand vs finger)
IP 2X> 12.5 mmSmaller objects and fingers
IP 3X> 2.5 mmThick wires or tools
IP 4X> 1 mmScrews, nails, wires
IP 5XDust protectedSome dust may enter, but cannot interfere with operation
IP 6XDust tightNo ingress of dust at all

The NEMA 250 test standard specifies the level of ingress protection as well as minimum enclosure design requirements. Regarding the level of ingress protection, the electrical enclosure testing involves determining protection from solids and liquids. Instead of an IP Code rating like IEC 60529, NEMA 205 testing provides an enclosure rating. The chart below shows the enclosure ratings and the protection requirements of those ratings.

TypeSolidLiquid
Type 1Falling dirtNo protection
Type 2Falling dirtDripping and light splashing water
Type 5Falling dirt, settling airborne dust, fibers, flyings and lintDripping and light splashing water
Type 12Falling dirt, circulating dust, fibers, flyings and lintDripping and light splashing water; seepage and light splashing of oil and non-corrosive coolants
Type 13Falling dirt, circulating dust, fibers, flyings and lintDripping and light splashing water; seepage, light splashing and spraying of oil and non-corrosive coolants
Type 3Windblown dust and falling dirtWater from sleet, snow and windblown rain
Type 3RFalling dirtWater from falling rain, sleet and snow
Type 4Windblown dust and falling dirtWater directed from a hose or from rain, sleet, snow and splashing water
Type 4XWindblown dust and falling dirtWater directed from a hose or from rain, sleet, snow and splashing water; increased corrosion protection
Type 6Falling dirtHose directed water and submersion that is temporary and at a limited depth
Type 6PFalling dirtHose directed water and submersion that is prolonged and at a limited depth

It should be noted NEMA 250 Types 1, 2, 5, 12 and 13 are for indoor use only. All other types can be indoor or outdoor.

UL 50 is similar to NEMA 250 in that it stipulates levels of protection and design criteria. The chart below specifies the levels of protection from solids and liquids for each enclosure type.

TypeSolidLiquid
Type 1Falling dirtNo protection
Type 2Falling dirtDripping and light splashing of non-corrosive liquids
Type 5Falling dirt, settling airborne dust, fibers, flyings and lintDripping and light splashing of non-corrosive liquids
Type 12Falling dirt, circulating dust, fibers, flyings and lintDripping and light splashing non-corrosive liquids; seepage and light splashing of oil and non-corrosive coolants
Type 13Falling dirt, circulating dust, fibers, flyings and lintDripping and light splashing non-corrosive liquids; seepage, light splashing and spraying of oil and non-corrosive coolants
Type 3Windblown dust and falling dirtWater from rain, sleet and snow
Type 3RFalling dirtWater from rain, sleet and snow
Type 4Windblown dust and falling dirtWater directed from a hose or from rain, sleet, snow and splashing water
Type 4XWindblown dust and falling dirtWater directed from a hose or from rain, sleet, snow and splashing water as well as corrosion protection
Type 6Falling dirtHose directed water and occasional submersion that is temporary and at a limited depth
Type 6PFalling dirtHose directed water and prolonged submersion at a limited depth

Design Requirements for Electrical Enclosures

As previously mentioned, only the NEMA 250 enclosure testing standard and UL 50 and UL 50E enclosure testing standards outline the design requirements for enclosures of electrical equipment. These standards cover a number of enclosure characteristics including finish, flammability, latching, material, mounting, sealing, strength, thermal and ventilation. The UL standards have additional requirements for bonding and grounding that the NEMA 250 tests do not.

When reviewing the design of an enclosure, here are some of the items a UL 50 and NEMA 250 test lab will be researching:

  • Does the enclosure ensure operator safety?
  • Is the equipment protected?
  • Will the enclosure perform in extreme temperatures and atmospheres?
  • Does the enclosure provide sufficient UV protection?
  • Are the doors and covers properly sealed?
  • Does the enclosure adequately prolong the life of the equipment?
  • Is the enclosure corrosion resistant?
  • Is the enclosure easy to access, install and repair?

Keystone Compliance is recognized as one of the best ingress protection testing labs in the country. Our capabilities and expertise allow us to meet nearly every ingress protection test requirement. Contact us to learn firsthand why so many companies partner with Keystone Compliance to meet their electrical enclosure test lab needs.