Choosing the right lab addresses foreign EMC test requirements close to home.
Developing complex electronic equipment that can meet today's electromagnetic compatibility (EMC) requirements remains a difficult engineering challenge. But, identifying a lab competent to perform the necessary compliance testing has become relatively easy in comparison.
The National Voluntary Laboratory Accreditation Program (NVLAP) administered by the National Institute of Standards and Technology (NIST) has grown to include eight major divisions from calibration laboratories to product testing. At the request of independent EMC test labs in the mid 1980s, the electromagnetic compatibility and telecommunications category was added together with a laboratory accreditation program (LAP).
According to NIST, Accreditation criteria are established in accordance with the U.S. Code of Federal Regulations (CFR, Title 15, Part 285), NVLAP Procedures and General Requirements and encompass the requirements of ISO/IEC 17025 and the relevant requirements of ISO 9002. Accreditation is granted following successful completion of a process which includes an on-site assessment, resolution of any deficiencies identified during the on-site assessment, participation in proficiency testing, and technical evaluation.
NVLAP provides an unbiased third-party evaluation and recognition of performance as well as expert technical guidance to upgrade laboratory performance. NVLAP accreditation signifies that a laboratory has demonstrated that it operates in accordance with NVLAP management and technical requirements pertaining to quality systems, personnel, accommodation and environment, test and calibration methods, equipment, measurement traceability, sampling, handling of test and calibration items, and test and calibration reports. NVLAP accreditation does not imply any guarantee (certification) of laboratory performance or test/calibration data; it is solely a finding of laboratory competence. 1
Labs satisfying the NVLAP criteria are listed in the Directory of Accredited Laboratories.2 All the listed labs are accredited, but labs inevitably will have varying capabilities and fields of expertise.
The highest level of the index includes the eight major category headings. Drilling down within a category presents a list of labs organized by the state or country in which they are located. NVLAP accreditation is available to labs outside of the United States if they meet the same requirements as those inside.
Selecting a lab in a particular state results in the presentation of the scope of that lab's accreditation. For a lab in the electromagnetic compatibility and telecommunications group, this is a list of the specific emissions, immunity, and safety test methods the lab has been judged competent to perform. As you can imagine, for a lab with comprehensive test capabilities, the list can be extensive.
Accreditation
In addition to the assurance it gives potential customers about a lab, NVLAP accreditation is important for several reasons. NVLAP is one of 42 organizations within 28 geographical areas worldwide recognized by the International Laboratory Accreditation Cooperation (ILAC). Within the United States, the American Association for Laboratory Accreditation (A2LA) is the only other recognized program besides NVLAP.
If you intend to sell your product in countries that ordinarily specify EMC test requirements other than those generally used in the United States, ILAC is important to you. According to the information on the ILAC website, ILAC is the world's principal forum for the development of laboratory accreditation practices, the promotion of laboratory accreditation, the assistance of developing accreditation systems, and the recognition of competent test facilities.•
Through mutual recognition arrangements (MRAs) with participating programs, the signatories to the ILAC arrangement for testing and calibration can recognize one another's accredited laboratories. This MRA is a major co-operative effort to enhance the objective of free trade throughout the world. 3
For example, Taiwan and the United States signed an MRA in 1999 that allowed NVLAP and A2LA to begin the process of accrediting U.S. labs to Taiwan's Bureau of Standards, Metrology, and Inspection (BSMI) EMC requirements. Today, United States-based manufacturers can obtain all the necessary BSMI testing and type-approval filing locally from a properly accredited lab.
It's obviously helpful to be able to test a product locally, but in this case, that's only the beginning. The applicant still must provide Chinese language versions of a product catalog, an instruction manual and technical specifications, and a completed application form. In addition, a product sample may be requested, pictures of the product are needed together with a block diagram, and of course, there is a fee to pay. Nevertheless, compared to the alternative of arranging for a lab in Taiwan to do the testing, the MRA is a big help.
Labs with facilities in multiple countries, for example, a test company with facilities in Japan and the United States and ties to regulatory agencies in both countries, may make your job easier if you are trying to develop a product one place for sale in another.
Within the United States, in addition to the FCC registration EMC labs generally have, several labs are part of the Underwriters Laboratories (UL) client agent program (CAP). If you need to obtain UL recognition of a product, you can elect to have a lab participating in CAP act as your agent representing you in all interactions with UL. According to Trace Laboratories, [This allows the lab] to coordinate and expedite all administrative aspects of your product recognition, alleviating you of the long and time-consuming process. [The CAP program also] allows the product testing to be performed in [a Trace] facility.
Similarly, some labs have attained FCC approval as a telecommunications certification body (TCB). If a lab acts as a TCB, that means it can approve most equipment that requires FCC certification. An example of a device that a TCB cannot approve is a 5-W, two-way radio that would require specific absorption rate/maximum permissible exposure (SAR/MPE) measurements.
TUV Rheinland of North America is one of several labs that operate as TCBs. In this case, the lab is approved to process FCC approvals for telecommunications terminal equipment under Part 68 as well as RF wireless device approvals under FCC Parts 15, 90, 95, and 97.
The comparison chart accompanying this article gives an indication of the EMC test areas in which a laboratory specializes. Because all U.S.-based EMC labs will be FCC approved to some level, there is no FCC column in the chart. In fact, there are a great many different groupings of similar tests that a lab may be capable of performing. The purpose of the chart is not to list each test method for which a lab is accredited but rather to highlight distinct capabilities.
For example, the SAE heading indicates automotive EMC test requirements, but in addition to the generic automotive electrical specifications, each of the major car companies has its own list of requirements. This situation is similar to the telecommunications network equipment building system (NEBS) test requirements that are amended by company-specific test requirements such as those of Verizon.
Wider Relationships
In reality, a two-dimensional chart can t express the complex relationships that have developed among many of the labs. Accreditation has long been a concern both separately and collectively within many countries. Because of its history, Nemko (Norges Elektriske Materiellkontroll) is a good example of a lab that offers much more than can be shown within the parameters of the comparison chart.
Started in 1933, Nemko provided safety testing and national approval of electrical appliances for use in Norway. Later, radio and emissions testing were added to its responsibilities. In 1990 the European Community Directives for product safety were adopted, whereby the traditional mandatory approval scheme was abandoned. In this connection, Nemko was transformed into an independent, self-owned foundation, having a council of representatives from different interest groups (industry and trade organizations, consumer associations, utility companies, etc.) as the highest level of supervision.
At the same time, the foundation established and became the sole owner of Nemko AS, which constitutes the central operating company and is responsible for what is today denoted the Nemko Group.• Nemko is a founding member of relevant multinational certification agreements, such as the Nordic EMKO-scheme, the European CCA, and the international CB-scheme and a leading player in international certification of IT equipment . The Nemko Group holds various national accreditations for testing and calibration services according to EN 45001/ISO/IEC 17025, for product certification according to EN 45011/ISO/IEC Guide 65, and for management system certification according to EN 45012/ISO/IEC Guide 62.
Some of the laboratories in addition have special accreditations by Russian GOSSTANDART, Chinese CNAL, Taiwanese BSMI, Korean RRL, Australian NATA, and German ZLS. Particular certification services through the subsidiary Nemko Certification AS (an IQNet member) [and] assessment and certification of quality systems to ISO 9000 are carried out. 4
Through a series of acquisitions and investments, today Nemko has facilities in many countries including two labs in the United States. In addition, Nemko issues approvals to other labs indicating that it will accept their test results. For example, CKC Laboratories operates a test site approved by Nemko.
Other Considerations
Once the necessary test equipment has been provided, the actual capability to perform a test and interpret its results rests with a lab's personnel. Certification of EMC engineers and technicians by the National Association of Radio and Telecommunications Engineers (NARTE) ensures that they have the requisite knowledge and understanding.
Some lab websites list ISO-9001, indicating that the lab's own quality system and documentation have been approved to this level. If a lab claims ISO-9001 approval, it should give you confidence that the facility is well organized and the management of the internal quality system is taken seriously. In fact, the ISO/IEC 17025 standard that is part of the assessment carried out by accrediting bodies relates to a lab's quality management system. So, if a lab is accredited by A2LA or NVLAP, it has been deemed to have an adequate quality management system.
Similarly, many experienced but uncertified EMC engineers and technicians have been performing meaningful tests for years. Nevertheless, NARTE certification, like lab accreditation, can help you decide to employ the services of a lab if you have no previous knowledge of its work.
Several more specific EMC accreditations can be found on test labs• websites. Harley Davidson specifies special tests as do many branches of the military such as the U.S. Coast Guard. Lloyds Register of Shipping issues an LR type approval, which requires special testing. EMC avionics testing is covered by RTCA DO specifications. And, medical electronics must be tested to distinct FCC and FDA regulations.
Summary
Before you start working with a lab, ensure that it has the capabilities you need to test your product. Proving that the device actually does meet the regulations of the countries in which it is to be sold always is the manufacturer's responsibility. Therefore, the choice of lab used to perform the EMC testing is an important one.
The temptation to put convenience ahead of other considerations should be avoided. Travel and lodging are additional expenses eliminated by using a local lab, and for straightforward emission and interference testing, that may be a good option. However, for more specialized testing, it can be less costly in the long run to choose the lab with capabilities that best fit your overall requirements.
The selection process can be considerably more complicated than the comparison chart implies. Several labs claim NVLAP or A2LA accreditation on their websites, and indeed they are listed by these agencies. However, the accreditation is by category of capabilities, so the NVLAP or A2LA listing may not include the test capabilities you require. If a lab regularly performs EMC testing, but its NVLAP or A2LA accreditation is for mechanical testing, that accreditation has not been entered in the comparison chart.
A large lab with several geographically separate facilities is likely to have different specialized capabilities at each site. For example, Trace Labs Central has extensive EMC capabilities, but Trace Labs East is much more suited to environmental testing. Of course, you could contract with Trace Labs to perform a complete suite of EMC and environmental tests on your product, but they may not all be done at the same location.
The good news is that almost without question there is a lab capable of providing the EMC test services you require. The comparison chart includes companies with wide ranges of capabilities. In addition, the NVLAP lab directory lists EMC labs by state. Similarly, you can choose labs from the A2LA list on the association's website. Once you have identified a likely candidate, you can view the detailed tests it is qualified to perform by examining its scope of accreditation document.
References
1. ts.nist.gov/ts/htdocs/210/214/summary.htm
2. ts.nist.gov/ts/htdocs/210/214/scopes/programs.htm
3. www.ilac.org/
4.express.nemko.com/portal/page? _pageid=34,33441,34_39495&_dad=portal&_schema=PORTAL
