Equipment enclosure environmental classification is another area where European standards language is showing up on equipment in this country, often leaving one wondering how to translate between systems. This month, we’ll review the international approach to enclosure ratings and compare it to the traditional National Electrical Manufacturers Association (NEMA) system.
A first digit of 2 or higher is required for the enclosure to meet the minimum Underwriter’s Laboratories (UL) criteria for protection against accidental contact with enclosed parts, which is required for most equipment installed in the US. This degree corresponds to protection against finger contact and entry of a solid object over 12 mm in diameter. A level of 5 or 6 is required for dust protection corresponding to the commonly used NEMA 12 construction.