CEC, NEC, IEC, CENELEC: Harmony or discord?

On the surface, hazardous-area standards appear harmonized, but underneath the king Christian Louboutin Sale
of the jungle still has not been crowned. After many years of debate and discussion, there are now harmonized standards for hazardous areas around the world. Or are there? In addition, if this is harmonization, why are there all sorts of new markings on products and what do they mean? Decoding these markings may not require use of the Rosetta stone, but it will require an understanding of protective techniques. This article, the second in a series that began in InTech's February 1998 issue, spells out the meaning of these markings and the differences among the protection techniques. The differences among codes Are the Canadian Electrical Code (CEC), National Electric Code (NEC), International Electrotechnical Commission (IEC), and the European Community for Electrotechnical Standardization (CENELEC) codes all the same? In a word, no. For products to pass North American (i.e CEC or NEC) zone testing, they must meet the IEC tests for zone classification in addition to ordinary location testing for either the U.S. or Canada. Ordinary location testing involves rigorous flame, material, shock, and other electrical tests. Having to perform this additional testing precludes immediate third-party approvals for European equipment under the North American zone classification system. For example, nonmetallic boxes approved for use under the IEC zone system must not hold a static charge to prevent sparking. Therefore, carbon is added to the material. The carbon increases the flammability of the plastic-not a consideration under the IEC concept-so it cannot pass North American flammability tests. Thus, in North America, the carbon must be removed, making it noncompliant with the IEC. Most materials cannot meet both North American ordinary location and Zone 1 IEC requirements. Having the North American approvals to the IEC standards also does not mean that Louboutin Boots
North American products can be sold immediately into European or CENELEC countries. The products would have to meet local construction requirements and have the CE mark. This mark shows that the manufacturer is International Organization for Standardization (ISO) certified and manufactures the product according to the relevant explosion-protective European norm or directive. Oversimplifying things, the CE mark is like a manufacturer's Good Housekeeping seal of approval. It is a difficult mark to achieve. Changing to the zone classification system in North America is a small step toward global standardization. There are still many obstacles in the way, however, before universal products are available. Most of these obstacles involve requirements for materials, local installation methods, and interpretation of electrical and mechanical testing methods. Such a confusing path to global standardization is not unique. When the 4-20 mA analog signal standards were agreed upon in the 1950s, a similar path was followed. The same happened as recently as 1994 when the Fieldbus Foundation was developed. Before then, the Interoperable Systems Project (ISP) and WorldFIP were pursuing the same goal-a universal fieldbus protocol. Agreement on a common protocol was finally reached after much disagreement and confusion. Markings become alphabet soup Global manufacturers want to develop products that can be sold into any market with few, if any, modifications. A good example of a hazardous-area product is an explosion-protected switch or contact block used in control stations to disconnect power. A contact block is shown in Figure 1 along with a U.S. quarter to show its size. For contact blocks to be commercially successful, they must be approved for all hazardous areas and small enough to be mounted in control station enclosures. A typical label designating Louboutin Tall Boots
that the contact block in this example meets North American, IEC, and CENELEC requirements would contain at least the information shown in Table 1. In addition, various third-party approvals (e.g Underwriters Laboratory [UL], Canadian Standards Association [CSA], or Factory Mutual [FM]) may also be listed, as well as any certificate numbers required by IEC or CENELEC. This label would also include catalog, serial, and model numbers; electrical ratings; wiring connections; and other instructions normally found on manufacturers' equipment.