If the IEC 60529 has set standards to establish the enclosures’ capability against harmful factors, the NEMA 250 Standard gives us with more protective characteristics and comprehensive guidelines of what these ratings mean.
NEMA ratings is comprised of detailed standards that ranges from the very basic level protection against ingress of solid objects up to full water submersion of enclsoures, to withstanding or containing internal explosions.
The NEMA ratings considers a lot of factors. Such as if the enclosure has knockouts or parts that are exposed that should remain operational at all costs. In order for a company to best use the NEMA 250 standard, they should consider numerous factors that will affect the way enclosures are being used. With this in mind, NEMA has changed the group codes so that the companies and engineers will be guided accordingly about the conditions the enclosures can give protection from.
The standard codes from the NEMA 205-2003 is for applications that are for non-hazardous applications. They are also specified about the enclosure type, their type of applications, and what type of environment they are engineered to protect against. These ratings are as of follows:
Type 1: these enclosures are engineered specifically for indoor use only. They are built to provide protection for personnel against accidental contact to hazardous and dangerous parts of the equipment. It also provides protection for the equipment housed inside the enclosure. It protects the equipment from ingress of solid objects such as falling dirt.
Type 2: These enclosures are built for indoor applications and like the type 1 rating it also gives protection for personnel that are using the equipment from hazardous parts and accidental contact. It also gives protection to equipment that placed inside the enclosure against ingress of solid objects (such as falling dirt.) It also gives a degree of protection from ingress of water. But only from dripping and light splashing water.
Type 3: these enclosures are built for either indoor or outdoor use and it gives a good level of protection for personnel against access to hazardous parts of the equipment. It also gives the users a degree of protection for the equipment placed inside the enclosure from accidental ingress of foreign objects and water ingress. This also includes sleet and snow formation. This enclosure will be undamaged from the external ice formation of the enclosure.
Type 3R: these enclosures are designed for both indoor and outdoor use. This rating provides protection for personnel against accidental access to hazardous parts of the equipment. It also gives protection for the equipment against accidental ingress of solid, foreign objects and water ingress. This rating also provides protection against sleet and snow formation. This rating will remain intact even after external ice formation.
Type 3S: these rating of enclosures are designed to be used for both indoor and outdoor applications and it gives protection for personnel against accidental contact from hazardous parts. This gives a level of protection for the equipment protected inside the enclosure from ingress of foreign objects and water ingress. This also gives protection from external ice formation. The external mechanisms of this rating remains operational when ice laden.