Introduction to Environmental Ratings Anderson Peeples Associate Design Engineer, CCS-Inc. CCS-Inc. www.ccs-inc.com December 13, 2012 Introduction to Environmental Ratings In the world of industrial electronics, there are phrases that simply don’t hold much weight when describing a system. The problem with such phrases (e.g. “waterproof” and “airtight”) is that these descriptions alone do not provide a quantitative measure of their meaning. To address this issue, many organizing bodies have developed design standards for engineers. Serving as a reference to customers, these standards provide specific criteria for the intended protection rating of a system. The National Electrical Manufacturers Association (NEMA) and the International Electrotechnical Commission (IEC) supply two of the most predominant standards, NEMA Ratings and Ingress Protection (IP) Ratings respectively. --- NEMA Ratings To help define the protective qualities of electronic system enclosures, NEMA has developed a rating system for enclosures containing components less than 1000 volts. These ratings are defined in the NEMA 250 standard and are separated into two categories: enclosures used in Non-Hazardous Locations1, and enclosures used in Hazardous Locations2. Each set of ratings is further divided into indoor and outdoor use, detailing features such as corrosion resistance, fabrication requirements, material selection, and gasket aging. Within the NEMA rating system, various industry standards have been adopted. For example, in many non-hazardous industrial applications, such as industrial automation and food packaging facilities, NEMA 4 and NEMA 4X have become the de facto standards. This is due to the fact that NEMA 4 is the minimum enclosure rating that provides protection against ingress of water. 3 This is important for applications where equipment may frequently need to be hosed down for cleaning purposes. The addition of the “X” suffix indicates that the system has further properties that limit its susceptibility to corrosion. In addition to NEMA ratings, UL 50/508 and CSA C22.2 No. 94 are also used to define protection ratings for enclosures in North America. These ratings utilize a similar numbering method for specifying the protection level of a system. Unlike NEMA ratings, which can be certified by the manufacturer, UL and CSA require testing by a certified lab to qualify an enclosure’s environmental rating. 1 Appendix A - Table 1 Appendix A - Table 2 3 Appendix A - Tables 3 and 4 2 CCS-Inc. www.ccs-inc.com December 13, 2012 IP Ratings Rather than, or often in conjunction with, specifying a NEMA rating for an electronic enclosure or system, manufacturers may specify an Ingress Protection, or IP, Code. IP codes are classified in the IEC International Standard 60529. These codes aim to provide a concise, but comprehensive, explanation of the protection provided and testing required for an enclosure or system. General IP codes utilize the prefix “IP” followed by two numerals4; for example, IP65. The first numeral in the code designates the degree to which the system is protected against solid foreign objects. The second numeral indicates the degree to which the system is protected against liquid ingress. As the numerical value increases, the system protection increases. In the event that either test parameter (solid or liquid protection) is not specified, the numeral for that portion is replaced with an X. For example, when testing a system only for liquid ingress per classification #6, the code would be IPX6. In addition to particulate and liquid protection ratings, IP codes may also include letters to signify further aspects of the system. A letter may be appended to the code to specify the degree of protection against hazardous parts.5 Additionally, a supplemental letter may be appended to the code to signify safety information about the system.6 With these options, a full IP code may take the form as shown in Figure A.7 Figure A. IP Code Format As with NEMA ratings, IEC’s IP ratings are “self-certifying,” meaning that they do not require third party test labs to certify enclosure designs. This leaves testing up to the manufacturer of the equipment. 4 Appendix A - Tables 5 and 6 Appendix A - Table 7 6 Appendix A - Table 8 7 An additional number may be added to indicate the impact resistance of the enclosure, though this is not included in the IEC 60529 standard. 5 CCS-Inc. www.ccs-inc.com December 13, 2012 Though NEMA ratings and IP codes both aim to clarify and quantify environmental protection for electronic systems, there are key differences between the two standards. Unlike NEMA ratings, IEC IP ratings do not specify fabrication practices, corrosion protection, or risk of explosion. For this reason, it is possible to have a NEMA rated enclosure that may satisfy all requirements for IP certification; however, a less stringent IP rating may not meet NEMA requirements.8 Determining the Appropriate Rating for Your Project’s Needs Due to the wide variety of ratings and enclosure protections available, choosing which rating is most appropriate for your application can be a daunting task. CCS Engineers are happy to help you analyze your system’s environment to determine what solution would best fit your project’s needs. To discuss your situation in detail with one of our engineers, contact us today. 8 Appendix A - Table 9 CCS-Inc. www.ccs-inc.com December 13, 2012 Appendix A – Rating Criteria Table 1. NEMA Enclosure Types for Non-Hazardous Locations Type Standard 1 Enclosures constructed for indoor use to provide a degree of protection to personnel against access to hazardous parts and to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt). 2 Enclosures constructed for indoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); and to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (dripping and light splashing). 3 Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and that will be undamaged by the external formation of ice on the enclosure. 3R Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and that will be undamaged by the external formation of ice on the enclosure. 3S Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and for which the external mechanism(s) remain operable when ice laden. 3X Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); that provides an additional level of protection against corrosion and that will be undamaged by the external formation of ice on the enclosure. 4 Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow, splashing water, and hose directed water); and that will be undamaged by the external formation of ice on the enclosure. 4X Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow, splashing water, and hose directed water); that provides an additional level of protection against corrosion; and that will be undamaged by the external formation of ice on the enclosure. 5 Enclosures constructed for indoor use to provide a degree of protection to personnel CCS-Inc. www.ccs-inc.com December 13, 2012 6 6P 12 13 against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and settling airborne dust, lint, fibers, and flyings); and to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (dripping and light splashing). Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (hose directed water and the entry of water during occasional temporary submersion at a limited depth); and that will be undamaged by the external formation of ice on the enclosure. Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (hose directed water and the entry of water during prolonged submersion at a limited depth); that provides an additional level of protection against corrosion and that will be undamaged by the external formation of ice on the enclosure. Enclosures constructed (without knockouts) for indoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and circulating dust, lint, fibers, and flyings); and to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (dripping and light splashing). Enclosures constructed for indoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and circulating dust, lint, fibers, and flyings); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (dripping and light splashing); and to provide a degree of protection against the spraying, splashing, and seepage of oil and non-corrosive coolants. CCS-Inc. www.ccs-inc.com December 13, 2012 Table 2. NEMA Enclosure Types for Hazardous Locations Type Standard 7 Enclosures constructed for indoor use in hazardous (classified) locations classified as Class I, Division 1, Groups A, B, C, or D as defined in NFPA 70. 8 Enclosures constructed for either indoor or outdoor use in hazardous (classified) locations classified as Class I, Division 1, Groups A, B, C, and D as defined in NFPA 70. 9 Enclosures constructed for indoor use in hazardous (classified) locations classified as Class II, Division 1, Groups E, F, or G as defined in NFPA 70. 10 Enclosures constructed to meet the requirements of the Mine Safety and Health Administration, 30 CFR, Part 18. Table 3. Comparison of Specific Applications of Enclosures for Indoor Non-hazardous Locations Provides a Degree of Protection Against 1* 2* 4 4X 5 6 6P 12 12K 13 the Following Conditions Access to hazardous parts X X X X X X X X X X Ingress of solid foreign objects (falling dirt) X X X X X X X X X X Ingress of water (Dripping and light slapping) X X X X X X X X X Ingress of solid foreign objects (Circulating X X X X X X X dust, lint, fibers, and flyings**) Ingress of solid foreign objects (Settling X X X X X X X X airborne dust, lint, fibers, and flyings**) Ingress of water (Hosedown and splashing X X X X water) Oil and coolant seepage X X X Oil or coolant spraying and splashing X Corrosive Agents X X Ingress of water (Occasional temporary X X submersion) Ingress of water (Occasional prolonged X submersion) *These enclosures may be ventilated. **These fibers and flyings are nonhazardous materials and are not considered Class III type ignitable fibers or combustible flyings. CCS-Inc. www.ccs-inc.com December 13, 2012 Table 4. Comparison of Specific Applications of Enclosures for Outdoor Non-hazardous Locations Provides a Degree of Protection Against 3 3X 3R* 3RX 3S 3SX 4 4X the Following Conditions Access to hazardous parts X X X X X X X X Ingress of water (Rain, snow, and sleet**) X X X X X X X X Sleet*** X X Ingress of solid foreign objects (Windblown X X X X X X dust, lint, fibers, and flyings) Ingress of water (Hosedown) X X Corrosive agents X X X X Ingress of water (Occasional temporary submersion) Ingress of water (Occasional prolonged submersion) *These enclosures may be ventilated. ** External operating mechanisms are not required to be operate when the enclosure is covered. ***External operating mechanisms are operable when the enclosure is ice covered. Table 5. IP Characteristics – Protection against Solid Foreign Objects First Test Means Numeral 0 No test required 1 Rigid sphere without handle or guard - 50mm Diameter 2 Rigid sphere without handle or guard - 12.5mm Diameter 3 Rigid steel rod with edges free from burrs - 2.5mm Diameter 4 Rigid Sphere without handle or guard - 50mm Diameter 5 Dust chamber with or without underpressure 6 Dust chamber with underpressure CCS-Inc. www.ccs-inc.com 6 6P X X X X X X X X X X X X ice Test Force 50N ± 10% 30N ± 10% 3N ± 10% 1N ± 10% December 13, 2012 Table 6. IP Characteristics – Protection against Water Ingress Second Test Means Numeral 0 No test required 1 Drip box 2 Drip box with 15° tilt Flow Rate Duration of Test 1mm/min 3mm/min Water spray at ±60° from vertical, no more than 200mm from EUT Water spray at ±180° from vertical, no more than 200mm from EUT Water jet from 6.3 mm diameter nozzle at a distance of 2.5-3 m 0.7l/min 10 min 2.5 min for each position 10 min 0.07l/min 10 min 12.5l/min 6 Water jet from 12.5 mm diameter nozzle at a distance of 2.5-3 m 12.5l/min 7 Immersion tank Water Depth: 0.15m above enclosure top, 1m above bottom Immersion tank Water Depth: Specified by manufacturer 1 min/m2 At least 3 min 1 min/m2 At least 3 min 30 min 3 4 5 8 By agreement Table 7. IP Characteristics – Additional Letter for Hazardous Parts Additional Level of Protection Letter A Protected against access with the back of the hand B Protected against access with a finger C Protected against access with a tool D Protected against access with a wire CCS-Inc. www.ccs-inc.com December 13, 2012 Table 8. IP Characteristics – Additional Safety Information Supplementary Significance Letter H High-voltage apparatus M Tested for harmful effects due to the ingress of water when the movable parts of the equipment are in motion S Tested for harmful effects due to the ingress of water when the movable parts of the equipment are stationary W Suitable for use under specified weather conditions and provided with additional protective features or processes Table 9. NEMA – IP Comparison IP Rating Needed IP20 IP22 IP24 IP53 IP54 IP55 IP66 IP67 IP68 Minimum NEMA Rating Required 1 2 3R, 3RX 5 12, 12k, 13 3, 3X, 3S, 3SX 4, 4X 6 6P NEMA 250-2003. Copyright National Electrical Manufacturers Association. Reprinted by permission. The author thanks the International Electrotechnical Commission (IEC) for permission to reproduce Information from its International Publication IEC 60529 ed.2.1 (2001). All such extracts are copyright of IEC, Geneva, Switzerland. All rights reserved. Further information on the IEC is available from www.iec.ch. IEC has no responsibility for the placement and context in which the extracts and contents are reproduced by the author, nor is IEC in any way responsible for the other content or accuracy therein. IEC 60529 ed.2.1 Copyright © 2001 IEC Geneva, Switzerland.www.iec.ch CCS-Inc. www.ccs-inc.com December 13, 2012 Appendix B – Organizing and Standards Bodies National Electrical Manufacturers Association 1300 North 17th Street Suite 1752 Rosslyn, Virginia 22209 Phone: 703-841-3200 Fax: 703-841-5900 International Electrotechnical Commission 3, rue de Varembé P.O. Box 131 CH - 1211 Geneva 20, Switzerland Phone : +41 22 919 02 11 Fax : +41 22 919 03 00 Canadian Standards Association 178 Rexdale Blvd. Toronto, Ontario Canada M9W 1R3 Phone: 800-463-6727 Underwriters Laboratories 2600 N.W. Lake Rd. Camas, WA 98607-8542 Phone: 1-877-854-3577 Fax: 1-360-817-6278 CCS-Inc. www.ccs-inc.com December 13, 2012