Initially, the IEC System for Conformity Testing and Certification of Electrical Equipment (IECEE), commonly referred to as the CB Scheme, was operated by the former European International Commission for Conformity Testing of Electrical Equipment (CEE). It was integrated into the International Electrotechnical Commission (IEC) in 1985. The origin of the CB Scheme was in Europe, where these nations were moving toward adopting a common set of IEC standards. Although the original intent was to provide a common test format to be used by all participating certifying agencies, manufacturers are increasingly using the CB test report as a final report to show compliance to a specific international standard.

What Is the CB Scheme?

The IECEE CB Scheme is an international system for acceptance of test reports dealing with the safety of electrical and electronic products. A manufacturer using a CB test report issued by one of the participating organizations can obtain certification in all other member countries of the CB Scheme. The CB Scheme is based on the use of international (IEC) standards, and each certifying agency issues CB test certificates to attest that product samples have successfully passed the appropriate tests. The main objective of the CB Scheme is to facilitate trade by promoting harmonization of national standards with international standards. It also promotes cooperation among product certifiers worldwide to bring product manufacturers a step closer to the ideal concept of "one product, one test, one mark."

Although this concept is commendable, the one-mark ideal is many years from being a reality. Also, universal acceptance of CB reports is not without problems. For instance, CB reports done by certain approval agencies are often less acceptable to other agencies, either for political or for technical reasons.

Increasingly, manufacturers are requesting a CB report to provide to their customers. It is considered to have a high level of credibility associated with it, and it can be used as part of the technical documentation file for CE marking. One big weakness is that, unlike agency certifications, a CB report does not have any factory follow-up inspections. However if a manufacturer is operating under ISO 9000, there should be a reasonable assurance of consistent production. The bottom line is that many manufacturers are asking for a CB report without a proper understanding of its value. Depending on the added cost, in many cases, manufacturers would get more benefit from a regular agency certification from one of the well-known certification agencies.

Who Can Issue a CB Report?

To issue a CB report, the national standards of the member country must be reasonably harmonized with the corresponding IEC standards for which participation in the CB Scheme is desired. The issuance and the acceptance of test reports by a national certification body (NCB) within the CB Scheme are limited to those IEC standards the NCB is officially recognized to conduct. (An NCB is a certification organization that grants nationally recognized conformity certificates to electrical products.) Currently, there are 43 member countries in the IECEE, 54 participating NCBs, and 129 CB testing laboratories.

Originally, only one certification body in each country was allowed to be a member. In 1991, the Canadian Standards Association, now CSA International, became the first North American organization to join the CB Scheme. Today, CSA enjoys the broadest scope of CB Scheme participation in North America, in part due to CSA's aggressive adoption of IEC standards. The limitation of one certification body per country delayed the entry of UL and other U.S.-based certification bodies into the CB Scheme because a number of them wanted to join at the same time. This resulted in the formation of national committees in all CB member countries.

The national committee of each member country designates the NCBs, which are then responsible for recognizing and issuing CB test reports and certificates. In the United States, this is the U.S. National Committee of the IECEE, operated by the National Electrical Manufacturers Association (NEMA). U.S. member certifiers are Entela, Factory Mutual Research Corporation, Intertek Testing Services, MET Laboratories, TUV Rheinland of North America, and Underwriters Laboratories. In Canada, it is the Canadian National Committee of the IEC, operated by the Standards Council of Canada (SCC). Canadian member certifiers are CSA International, Entela Canada, Intertek Testing Services, and Underwriters Laboratories of Canada.

It should be noted that not all of the offices of these certifiers are authorized to submit CB reports, and many of them have participating partners that conduct testing and report preparation. This area is somewhat murky. Also, each of the certifiers is limited to specific IEC-based standards. See http://www.cbscheme.org/cbscheme/html/cbcntris.htm for a complete list of countries and certifiers in each country.

A CB report can only be obtained from agencies in countries where the country in question has adopted the IEC standard for which the report is desired. Most countries are adopting the IEC standards, so this looks like a good system. The national standards are usually numbered in a recognizable fashion—for information technology (IT) equipment, for example, the IEC standard is IEC 60950. The same number is used in Canada, Europe, and the United States, but it is prefaced by EN, CSA, and UL, respectively.

IEC and CB Scheme logos.

The standards usually contain country-specific deviations and interpretations that manufacturers need to be aware of. This is particularly true of operator manuals, where it used to be acceptable to say that only the English manual was reviewed but compliance to deviations was claimed even where a country- or language-specific manual is required.

There are also specific construction requirements. For example, in Norway, due to the IT power-distribution system used, supplementary insulation for a primary circuit is required between any circuit intended for connection to a telecommunications network (SELV and/or TNV) and any circuit that has a connection to a protective earth terminal. This requirement sounds simple, but many designs fail to take notice of this and therefore don't qualify for a CB report that covers Norway. Designing to comply with the national deviations of any country that product is to be sold into is very important.

A CB Testing Laboratory (CBTL) is a laboratory recognized in the CB Scheme to conduct testing and issue CB test reports in one or more product categories under the responsibility of the identified NCB(s). CBTLs may operate in the scheme for different NCBs with which they are associated; however, when employed by multiple NCBs, they can only do a given category, e.g., OFF (IT equipment) for a single NCB.

Testing on Manufacturer's Premises (TMP). This is a CB procedure allowing an NCB or a CBTL to conduct testing at a manufacturer's testing laboratory. The staff of the NCB or CBTL must carry out all tests under this program.

Supervised Manufacturer's Testing (SMT). This is another CB Scheme procedure for recognition of test data generated at a manufacturer's testing laboratory. The SMT procedure is used to assess and qualify a manufacturer's capability to carry out tests in specified product areas. Test reports and certificates issued by an NCB under the SMT are supposed to have the same status in the CB Scheme as any other CB report and certificate. However, there have been many instances of these reports not being readily accepted. It may also be possible for a manufacturer to appoint an independent laboratory as its test laboratory.

Witnessed Testing at an Independent Laboratory. There are efforts under way to officially accept witnessed tests done by a laboratory not qualified as a CBTL, TMP, or SMT. There has been long-term, widespread use of independent laboratories by various NCBs. In these cases, the NCBs simply put their name on the certificate as the testing location. However, the CB Scheme auditors are objecting to this practice. It is likely that this third class of testing location will be officially recognized, possibly as early as this summer.

What Are the Benefits?

The CB Scheme can provide significant benefits to those manufacturers who wish to export their products to countries that participate in the scheme. Manufacturers can use the NCB of their choice and have their products tested only by that NCB, including testing to the national differences of the product's destination countries. The CB test report and certificate obtained from one NCB can be used to obtain national approvals in many other member countries through their participating NCBs.

Although the manufacturer is required to submit an application and may also be required to submit a product sample in the country of destination, additional testing should not be needed. The reality is somewhat different—acceptance depends on the accepting NCB trusting the originating NCB's work and acceptance of the internal components used. Some certifiers are notorious for doing additional testing and for having additional component requirements that are not readily identifiable.

An application for obtaining a CB test certificate may be submitted to any NCB authorized for the relevant IEC standard. The applicant may be either a manufacturer or an entity authorized to act on behalf of a manufacturer. The application procedure for obtaining product certification in the manufacturer's target markets entails submission of the following items: an application to an NCB in the target country, the CB test certificate, and the test report. A sample of the product is usually required to verify that the product is the same as initially tested by the issuing NCB.

The CB test certificate is a formal CB Scheme document issued by an authorized NCB. It informs other NCBs that a sample of the product tested was found to be in compliance with the applicable requirements. CB test certificates should not be used for advertising purposes; however, reference to the existence of a CB test certificate is permitted.

The CB test report is a standardized report in a clause-by-clause checklist format referencing the requirements of the relevant IEC standard. The report provides clear and unambiguous results of all the required tests, measurements, verifications, inspections, and evaluations. It also contains photographs, circuit schematics, and artwork drawings as well as a description of the product. Under the rules of the CB Scheme, a CB test report is considered valid only if accompanied by a CB test certificate.

An NCB can test and evaluate products to national differences of other countries if it has the necessary test equipment and expertise. These additional tests are documented in the supplements to the CB test report that are generally accepted by the recognizing NCBs.

The national differences of all countries participating in the CB Scheme are supposed to be published in the CB Bulletin. Unfortunately, there are many delays in getting the information published, and information is often incomplete. Further delays are caused when each NCB adds the deviations to their own version of the official checklist. Each CB certificate issued by an NCB must be registered under the CB Scheme, and a fee must be paid. IT equipment (IEC 60950) is the largest category, with 6466 certificates issued in 1999, 8232 in 2000, and 11,191 in 2001. Overall, 15,893 certificates were issued in 1999, 19,624 in 2000, and 24,259 in 2001.

A typical CB certificate.

Where Are the Problems?

When a product is received for evaluation, the NCB often discovers that the designers do not appear to have a copy of the safety standard, or if they do, they have not understood the meaning of what they are reading. A typical IEC standard contains 400-plus pages, which can be a daunting task to read. In addition, national standards generally do not contain the deviations for other countries.

To properly design a product to comply with the electrical safety requirements of the countries that are key to the marketing goals requires that a designer has at least three publications. In the case of IT equipment, these publications would be the latest edition of (currently the third edition) of CSA/UL 60950, the latest edition of IEC 60950, and a current copy of the CB Bulletin for the country deviations. These can be purchased on-line at http://webstore.iec.ch/.

Increasingly, products being evaluated are having many countries pulled from their market list because of a failure to meet the national deviations for those countries. Here is a small sampling of failures from a recent evaluation:

Although the goal of the CB Scheme is to provide a harmonized international environment, manufacturers must still comply with local electrical installation codes and practices. This creates deviations for many countries, and the list is growing as more countries join the CB Scheme.

It is good to have any product preevaluated for compliance before the design is locked in. This should ensure a much more satisfying product approval experience.