Designers of electronic products are frequently faced with the question “how do I find a high-quality EMC testing laboratory where I can confidently test my products?” The emphasis of the great majority of design entities is on obtaining: 1) quality preliminary testing of EMC characteristics to refine the design of their products; and 2) quality final testing of their product for regulatory approvals. The final design, of course, is what gets manufactured and released to the general population for their use in daily life. This article is intended to aid designers in finding and utilizing high-quality EMC testing laboratories.
FCC Rules Impact
The United States is a “target rich” environment for electronic equipment designers and most designers know that their products will have to meet U. S. Federal Communications Commission (FCC) rules in order to legally market their designs in the U.S. Recently, the FCC passed some new requirements that directly impact EMC testing labs.
The FCC’s new equipment authorization rules were adopted in ET Docket No.13-44 and published in the U.S. Federal Register on June 12, 2015, with an effective date of July 13, 2015. Two new standards were incorporated by reference in the rules, ANSI C63.4-2014 and ANSI C63.10-2013. Those two new standards have a one year transition period, and they will become fully active on July 13, 2016.
The new rules provide for new test site validations for EMC labs used to make radiated emission measurements above 1 GHz. The new test site validation criteria has a three year transition period that ends July 13, 2018. During that three year transition period, EMC labs can continue to meet the validation criteria in ANSI C63.4 (which has two alternatives). But, after the July 13, 2018 deadline, all EMC labs must meet the criteria in CISPR 16-1-4 in order to test products for FCC compliance for radiated emissions above 1 GHz.
Internal and External EMC Labs
If the designer is part of a large organization, they most likely will have an internal EMC lab that they can approach and schedule time for a preliminary or final (qualification) test of their product. However, if the internal EMC lab is tightly-scheduled, the project manager may be invited to look outside the company for an external source of EMC lab expertise in order to meet his/her project schedule. In the ideal case, the project manager may have the opportunity to investigate several competing labs and solicit bids from the same.
If the designer is not part of a large organization, then the project manager for the development project is immediately put into the position of soliciting bids and information from independent third-party EMC labs.
When soliciting bids from external EMC testing labs, first impressions are significant. If the EMC testing lab does not return phone calls, that is an indication of a lack of interest in new business or a lack of an organizational structure to respond to customer inquiries. Either way, you may want to seek another EMC testing lab.
If the testing lab returns your phone call, then the next step is to ask for a bid to do certain tests that will allow you to verify your design or qualify it for shipment to customers. The EMC tests needed for your commercial product will, in general, consist of both emission and immunity tests. These tests will encompass U.S. emission requirements, European Union (EU) and international emission requirements, and EU and international immunity requirements.
Once the bids are received and compared, you are ready to make an on-site visit to the potential EMC lab. Again, the first visit to the EMC lab is critical for both you and the lab. First impressions of the lab are just as important as the first phone-call impression. The first Impression of the lab consists of both a “gut check” and an “intellectual check.”
The “gut check” is a feeling about the lab and its people. If you don’t feel right about the lab personnel or the lab’s facilities or equipment, you might surmise that your uneasiness is based on a deeper issue you will uncover when you use the lab.
The “intellectual check” is more of a technical checklist concept where you either have a mental checklist or a written checklist on specific administrative or technical items that you want to investigate. These items could include test equipment, calibration of the test equipment, test facilities, technical personnel resumes and sample test reports.
Most EMC testing labs used by designers are geographically situated in close proximity to a concentration of intended users. This should allow for an easy inspection of the lab. The EMC lab should be proud to show you their lab and to discuss their capabilities. They should also have an open-door policy that allows their customers to observe the testing of their products through the entire battery of EMC tests.
A lab that is geographically close to its customers also allows engineers and technicians who designed and developed the product the freedom to troubleshoot the product conveniently if it fails one of the EMC tests during preliminary testing. That is, they can readily make modifications to the products because the electrical engineers, mechanical engineers, and power-supply engineers are close at hand. An EMC lab that is distant from the design center makes it more difficult (telephone consulting), more time-consuming (extra travel time), and more costly (travel costs).
If the lab is geographically close, the first visit leaves you with a positive impression, and the financial bid is in the acceptable range, then it is time to check on some of the other attributes that a high-performing EMC lab should possess.
One of the key qualities that a high-performing EMC testing lab will possess is that it hold suitable laboratory accreditations. In the U.S., there are four accreditation bodies recognized by the FCC for EMC testing. They are: 1) the American Association for Laboratory Accreditation (A2LA); 2) the U.S. Department of Commerce’s National Institute of Standards and Technology (NIST) National Voluntary Laboratory Accreditation Program (NVLAP); 3) the Laboratory Accreditation Bureau (LAB); and 4) ANAB, an ANSI-ASQ National Accreditation Board Company. A2LA, LAB, and ANAB are private organizations, while NVLAP is part of the U.S. government.
It should be noted that there are other qualified accreditation bodies outside of the U.S. that can accredit labs internationally. In some cases, EMC testing labs in countries other than the U.S. maintain accreditation from one of the four U.S. accreditors. The International Laboratory Accreditation Cooperation (ILAC) is the international-body that designates accreditation bodies around the world and assures that accreditation bodies that are members of ILAC are meeting standard accreditation requirements. This enables accreditation bodies to accept one another’s accreditation results.
Accreditation bodies will assess EMC testing labs to the requirements of ISO/IEC 17025, General Requirements for the Competence of Testing and Calibration Laboratories. The latest version of this standard is dated 2005. It superseded the first edition of ISO 17025 released in 1999 (it replaced ISO/IEC Guide 25 and European Norm (EN) 45001).
Laboratory accreditation has been incorporated into U.S. law by the FCC. The Commission allows a large number of electronic products that are tested in accredited EMC testing labs to be placed on the market with no further government approval for EMC criteria. The specific process using accredited EMC testing labs is called the Declaration of Conformity (DoC) by the FCC. It is preceded by a Manufacturer’s Declaration of Conformity or a Self-Declaration of Conformity before the official declaration based on testing in an accredited testing lab. Oftentimes, an accredited EMC testing lab will issue a Declaration of Conformity certificate, indicating that the product complies with the appropriate FCC rules. The responsibility for continued compliance of the product as it is manufactured, of course, lies with the designer of the product.
Declarations of Conformity can apply to such digital/electronic devices as Class B personal computers, Class B computer peripherals, citizens band (CB) receivers, television interface devices, consumer and industrial, scientific and medical (ISM) equipment. The DoC concept has allowed products to be marketed more quickly while at the same time protecting licensed communications services in the U.S.
Because the laboratory accreditation process is built around an international standard, this allows products to potentially flow more smoothly in the world trade arena. This is accomplished by an EMC lab obtain accreditation for appropriate test methods, by the lab writing a test report that complies with ISO/IEC 17025 report requirements, and by the lab properly using the accreditation body’s symbol and logo on the test report.
The accreditation body’s “mark” on the test report signifies that the testing was done in an accredited lab and that the tests performed by the lab were within the scope of its accreditation. (Note – the test report must also indicate in the body of the report whether tests were performed that were not on the testing lab’s scope of accreditation). This sends a clear signal to any importing country that the product is in compliance with the stated requirements. Oftentimes, this means that the product will be cleared quickly through customs and be placed on the market. Without the appropriate certification mark on the test report, the product could be destroyed, returned to the country of origin (originating designer/manufacturer), or retested in an accredited laboratory in the country where the product is to be marketed.
ISO/IEC 17025 – Management Requirements
The international standard on criteria for testing labs is ISO/IEC 17025 which includes both management requirements and technical requirements. Management requirements are very similar to those found in ISO 9001:2008, Quality Management System – Requirements, and encompass the following areas:
- Management System
- Document Control
- Review of Requests. Tenders, and Contracts
- Subcontracting of Tests (and Calibrations)
- Purchasing Services and Supplies
- Service to the Customer
- Control of Nonconforming Testing (and/or Calibration) Work
- Corrective Action
- Preventive Action
- Control of Records
- Internal Audits
- Management Reviews
The “organization” of the EMC testing lab is its management structure (for example, who is the president of the lab and who has key areas of responsibility under the president such as quality control). It is also the organizational entity that can be held legally responsible for the actions of the EMC testing lab. A potential user of the EMC lab should look at the organizational structure and be comfortable with the organizational chart and with the qualifications of the individuals filling the key slots.
The EMC lab’s “management system” must be appropriate to the scope of the EMC activities offered. The management system must be documented, and should have detailed policies, procedures, programs, and specific work instructions sufficient to assure a high-quality test effort on a consistent basis. The management system must be in written form, and can be available in hard-copy format or stored electronically on a server.
The “document control” portion of the management requirements can be checked by looking at the EMC testing lab’s quality manual and by examining some representative documents. The key element is that the lab should demonstrate a process that is “under control,” that is, a process in which all documents are identifiable and controllable.
The fourth management requirement is “Review of Requests, Tenders, and Contracts,” and it is very important for a potential user of the testing lab. This requirement will encourage the lab to review your request for a test and establish a contract between the lab user and the lab. The contract should specify the requests of the lab user and it should allow for amendments to the contract assuming agreement by both parties.
For testing labs, the management requirement that is stated as “Subcontracting of Tests and Calibrations” should be read as “Subcontracting of Tests.” That is, because ISO/IEC 17025 is written for both testing labs and calibration labs, the testing lab must read the requirements as stated for a testing lab and not as stated for a calibration lab. (For example, calibration labs would read the management requirement as “Subcontracting of Calibrations.”) An accredited testing lab may subcontract some of its tests to another accredited testing lab due to a temporary lack of test equipment or other similar legitimate reasons. In general, a long-term subcontract relationship is not allowed since an accredited testing lab must have the capability to perform the tests on its scope of accreditation.
For an EMC testing lab, the management requirement “purchasing of services and supplies” – which are critical to the operation of the lab – is most often focused on its purchase of calibration services. The calibration of the EMC testing lab’s equipment is a key factor in making proper measurements that are traceable to national metrology institutes. A user of the EMC testing lab should feel confident that the calibration labs being used by the EMC testing lab are accredited for calibration services.
“Service to the Customer” is that aspect of the EMC testing lab’s operation that makes a user feel comfortable about the lab. For example, the user should be allowed to observe the lab’s performance in testing their products. Excellent communications between the customer and the EMC Lab is also consistent with this area of the management requirements.
If you, as a customer, complain to the EMC testing lab, how does the lab react? Do they investigate the complaint and make changes? Or, do they ignore your complaint and continue on with the approach that “this is the way we always do this test.” A high-quality lab will respond to customer complaints and, if warranted, make appropriate changes in their procedures after a thorough investigation.
“Control of Nonconforming Testing” is that area of the administrative requirements that addresses mistakes made by the EMC lab in its testing service. Does the lab offer to redo the test that was done incorrectly for no additional charge? A user of the lab should familiarize himself with the testing lab’s philosophy in this area.
The next area of management requirements is “Improvement.” The EMC testing lab should have a “continual improvement” philosophy consistent with quality assurance theory and practice. One location that this emphasis on “Improvement” can be illustrated is in the EMC testing lab’s quality policy statement, which should be prominently displayed in the lab, and clearly understood by lab employees.
The next part of the management requirements, “Corrective Action,” is closely related to “Complaints” and “Improvements.” This part of the management requirements addresses the actions the lab takes to satisfy customer complaints. When a user identifies a problem, it is essential that the lab institute a root cause analysis and follow their logical trouble-shooting to a solution to the problem.
A fair question for a potential user to ask the EMC lab is “what corrective actions have been taken in the past to satisfy customer requirements?”
“Preventive Action” is more difficult for a potential user of the EMC testing lab to identify. It involves the continuous improvement aspect of the ISO/IEC 17025 standard. One example of a preventive action situation is a lab that has calibration complaints on antennas in the frequency range below 1 GHz should also investigate potential calibration problems on antennas above 1 GHz as a preventive measure.
The next management requirement is “Control of Records.” In the context of ISO/IEC 17025, the records can be either a quality record or a technical record. Quality records include reports from internal audits, minutes of management reviews, records of corrective actions, and records of preventive actions. Technical records include accumulations of data and information which result from carrying out tests and which indicate whether specified quality or process parameters are achieved. They may include forms, contracts, work sheets, work books, check sheets, work notes, control graphs, external and internal test reports, customers’ notes, customers’ papers, and customers’ feedback.
The records should also identify personnel responsible for the performance of tests and checking of the test results. How does the lab protect and control its records? What evidence do you see that the lab has its records held securely and in a manner to maintain confidentiality? Your test results will become part of the record-keeping system, so make sure your privacy and confidentiality are protected.
Every EMC testing lab should perform an internal audit at least yearly. This is a semi-formal audit done by member of the lab and it is intended to review the operations of the lab including both management and technical requirements. The lab should have a record of its past internal audits and a plan and schedule for future audits.
“Management Reviews” are intended to be performed by the lab’s upper management. There are 11 specific areas that shall be reviewed in a management review. They include:
- The suitability of policies and procedures
- Reports from management and supervisory personnel
- The outcome of recent internal audits
- Corrective and preventive actions
- Assessments by external bodies
- The results of inter-laboratory comparisons of proficiency tests
- Changes in the volume and type of work
- Customer feedback
- Recommendations for improvements
- Other relevant factors such as quality control activities, resources, and staff training
Minutes of annual management reviews should reflect the status of the above eleven items.
ISO/IEC 17025 – Technical Requirements
The additional technical requirements section of ISO/IEC 17025 is what differentiates it from the ISO 9001 requirements. An EMC testing laboratory can meet ISO 9001 and still not be in full compliance with ISO/IEC 17025 unless it also meets that standard’s technical requirements. On the other hand, a lab that is accredited to ISO/IEC 17025 can be considered to be in full compliance with ISO 9001 and its management requirements.
The ISO/IEC 17025 technical requirements are:
- Accommodation and Environmental Conditions
- Test (and Calibration) Methods and Method Validation
- Measurement Traceability
- Handling of Test (and Calibration) Items
- Assuring the Quality of Test (and Calibration) Results
- Reporting the Results
“General” is the first section of the technical requirements. It is basically a listing of the requirements in the technical requirements portion of ISO/IEC 17025 plus a comment on the “total uncertainty of measurement.”
“Personnel” is the next section of the technical requirements. People make a testing lab successful. An EMC testing lab provides an engineering service, and a service business must be people-oriented. So, as a customer of a testing lab, you should feel comfortable with the technical personnel you are going to be working with. You should check their technical qualifications, such as engineering degrees, technical associate degrees, years of experience in EMC, personnel certificates from iNARTE and other similar personnel certification bodies.
On-going education is also important. Do you see the individuals from the EMC lab attending local meetings of the IEEE EMC Society? Are the technical personnel actively attending workshops and seminars on EMC? Test results on your product are a function of the technical training of the technical personnel coupled with excellent test equipment and test facilities. The customer of the lab should make sure the lab personnel have had adequate training and that they are keeping up to date on the latest changes in standards, design, test equipment and other issues pertinent to EMC testing.
An EMC testing lab relies heavily on its laboratory facilities. So, the technical requirement titled “Accommodation and Environmental Conditions” is a key aspect of a testing lab. For example, does the lab have both 50 Hz and 60 Hz power available? Does it have a variety of voltages for alternating current available? Make sure that the lab has a power source for alternating current that will satisfy your product design. You will also want to see a separation of emission and immunity testing activities so that the immunity testing does not adversely affect the radiated and conducted emission profiles of the product. Does the lab have the capability to test for radiated emissions at a 10 meter antenna distance? As mentioned earlier in this article, good housekeeping can be an indication of the quality of the lab. Look for a well-maintained lab and the lab results will usually reflect a high-quality lab.
A testing lab should read the next technical requirement as “Test Methods and Method Validation.” (Again, calibration labs would read the requirement as “Calibration Methods and Method Validation). It is important to ask the lab about their scope of test methods. How many tests do they have the capability to run?
The test methods should be documented, including frequency ranges and amplitudes of various tests. The testing lab should have a verification process for each test method so that the lab knows the test equipment is operating properly for the test on the customer’s product. This verification is a system check that assures the EMC test equipment and the corresponding test method are both in synchronization. This verification process can be combined with daily and intermediate checks of test equipment to assure a repeatable and reproducible test of the customer’s products.
Equipment for EMC testing labs is expensive especially for large semi-anechoic (SAC) and fully-anechoic chambers (FAC). As a potential user of the EMC lab, you may want to ask for a list of the lab’s EMC test equipment as well as a description of the lab’s test facilities. Once you arrive at the lab, you should double-check the calibration status of the lab’s test equipment. Each piece of equipment that is being used for the testing should have a calibration tag on it with a current calibration status indicated on the tag. High-quality test equipment will help assure a high-quality testing experience.
The next technical criterion for an ISO/IEC 17025 accredited lab is “Measurement Traceability” which is closely associated with the lab’s test equipment. A calibrated piece of test equipment has to be traceable to the international system of units through a direct path to a national metrology institute. In the U.S., the national metrology institute is the National Institute of Standard and Technology (NIST). The best way to do this is to assure that the calibration labs used by the testing lab are accredited to ISO/IEC 17025. This assures that the calibration lab’s measurement standards and measurement instruments are linked to relevant primary standards through an unbroken chain of calibrations.
Sampling is an important aspect of the technical characteristics of a testing lab. However, most independent testing labs will test products brought to the lab not knowing what sampling plan, if any, was followed by the customer in selecting the product to be tested. Internal EMC labs sometimes have more input to a sampling plan of manufactured products and their selection for occasional testing of their company’s manufactured products.
“Handling of Test Items” is the eighth technical requirement of ISO/IEC 17025. This deals with how test items are delivered to the EMC lab for testing, for example, are they hand-carried, delivered by a company truck, delivered by a common carrier such as UPS, Federal Express, etc. This topic also covers identity of the products while they are in the lab, security and confidentiality of the products while they are in the lab and, finally, the shipment of the test items back to the customer.
Assuring the quality of test results is usually combined with daily and intermediate checks. The EMC lab may also participate in inter-lab proficiency testing and other techniques for checking and verifying the quality of the lab’s test results.
The last part of the technical requirements is the “Test Report” or, as ISO/IEC 17025 refers to it, “Reporting the Results.” A prospective user of a test lab should ask to see a test report template for the lab. The test report should comply with the requirements of Clause 5.10 (“Reporting the Results”) of ISO/IEC 17025.
Look for laboratory accreditation to ISO/IEC 17025 as a first step in finding a high-quality EMC testing lab. However, it should be noted that even accredited testing labs can make mistakes.
It is important to check the scope of tests for an accredited lab to make sure the scope encompasses the tests required for the customer’s product.
An accredited lab that is qualified to perform the necessary scope of tests will provide the customer a complete test report that will ease the acceptance of the product in national and international markets.
In general, you will be satisfied with accredited EMC labs because there is a higher probability of a successful test using calibrated and high-quality test equipment. This should allow easy marketing of your product relative to EMC requirements.
Daniel D. Hoolihan is the founder and principal of Hoolihan EMC Consulting. He serves as chair of the ANSI-ASC C63 Committee on EMC. He is also a past-president of the IEEE’s EMC Society. He can be reached at danhoolihanemc @ aol.com.