Introduction
This blog will provide the reader with an introduction to some of the items that need to be looked at when auditing an EMC laboratory with an eye to placing them on your company’s approved lab list. This is not an in-depth look at each item but is based on my experiences auditing laboratories (both in-house and 3rd party) over a number of years.
Key Requirements
There are a number of items that you must review. Based on experience, laboratories will have varying levels of compliance in these areas. As a quick list, these areas to be looked at fall into a few key categories. If the lab meets the first requirement the odds are that the lab will be in good shape with the second.
- Does the lab have accreditation from an appropriate 3rd party agency? The assessment requirements for accreditation include a serious review of the laboratory’s quality system, as well as an assessment of its ability to test to the standards listed in its Scope of Accreditation.
- Does the lab have a written quality system in place and is it being used? The contents of this quality system should meet the requirements in ISO/IEC 17025. If you don’t have a copy of this document it is recommended that you obtain one and become familiar with its requirements.
- Review the Scope of Accreditation. Does it cover all the standards that might apply to your product? If not, either work with the lab to have the missing standards added or find a different lab.
- If you have the expertise, or can hire a consultant with the expertise, audit the laboratory yourself to make sure that they truly are properly equipped and are properly performing the required tests.
We’ll go over each of these points in more detail.
Laboratory Accreditation and Written Quality System
Is the laboratory accredited by a national laboratory accreditation body to the requirements in ISO/IEC 17025? This can be vitally important for the acceptability of the lab’s report by various national regulatory bodies. Accreditation is an important step in establishing the laboratory’s ability to perform testing in an acceptable manner with repeatable results. In the U.S. three of the accreditation bodies are the American Association for Laboratory Accreditation (A2LA), the National Institute of Standards and Technology’s National Voluntary Laboratory Accreditation Program (NIST NVLAP) and the ANSI National Accreditation Board (ANAB). ANAB becomes fully owned by ANSI effective December 28, 2018, ANSI having secured ownership of the 50% of ANAB owned by the American Society for Quality (ASQ) effective on that date.
A laboratory being accredited is not a sole criteria for acceptance by your company or business unit, however. It is an important start.
Part of the accreditation process is the preparation of a written quality system. This document, or collection of documents, will call out a number of vitally important items in how the laboratory is managed and operated. It will show how the laboratory is independent of other organization within a company, for example. It will show requirements for calibration of test equipment, how often they are to be calibrated, how calibration records are stored and calibrations for individual pieces of equipment are maintained and properly used. It will contain the documentation for each test procedure, showing how that test is to be performed. It will show how personnel are trained, along with the training records for each individual performing testing. There will be a document (or section) detailing how complaints about the laboratory are handled. These are just some of the items that the quality system will address.
As part of your audit of the laboratory you should go through the laboratory’s quality system and see how they actually perform to it. Talk to the personnel performing tests and see if they are aware of the quality system and how they obtain copies of it. Are printed copies of documents marked to show that they are indeed copies? Do they show the effective date for the document? How do the people performing the tests know that they are using the latest version of the document? You get the idea, ask questions and see if the quality system is more than just words on paper.
Scope of Accreditation
Just because a laboratory is accredited to perform EMC testing doesn’t necessarily mean that they are accredited to test your product to the standards that your product must meet. This is where the Scope of Accreditation comes in. This is a separate document, provided by the accrediting body that shows what standard, or standards, the laboratory’s accreditation covers. Just because a laboratory is accredited to test to the FCC Rules, Part 15, Subpart B using ANSI C63.4-2014 doesn’t mean that they are accredited to test to CISPR 32, for example. Both would have to be listed in their Scope of Accreditation.
The Scope of Accreditation must list every standard that you need your product tested to, both the product family standards, such as CISPR 32 or CISPR 35, and the basic standards that are called out by those product family standards. Not only do the correct standards have to be called out, the correct editions of those standards must also be called out. There may be changes in test set-ups between editions of the basic standards and you must know that the correct one is being used for the product family standard. Some standards use dated references that may not be the latest edition. Other standards may use undated reference and you must know what the latest edition is or will be, as of the date of the test. The Scope of Accreditation will tell you if the laboratory’s accreditation is valid for the testing you need done.
Is the Laboratory Truly Capable of Performing Your Needed Tests?
This is the step that requires the deepest understanding of the standards to which your product is to be tested – by you! It has been my experience that many laboratories may be accredited, but they still lack an understanding of the details of the standards to which they are testing. The on-site assessor for the accrediting body may know ISO/IEC 17025 forward and backward, and the laboratory’s paperwork may be excellent and cover all the points required, but when the assessor went into the laboratory they may not catch the errors in the laboratory set-up or processes. This article will finish with some quick examples that I found while auditing laboratories in order to place them on his approved EMC laboratory list. These are only a few examples.
Examples
A laboratory had a portable instrument to measure barometric pressure at the test stand as required by IEC 61000-4-2 for electrostatic discharge testing. There was no calibration sticker on this instrument, as required by their quality system. When asked about this, the laboratory personnel stated that there was no calibration facility in their country that could calibrate this instrument. No calibration lab could calibrate a pressure gauge? That was a simple thing to write up. The next time the blogger visited that laboratory (a few years later) there was a calibration sticker on that instrument.
A laboratory did not maintain the 40 cm distance behind the EUT and cables to the vertical reference plane required by CISPR 22 (and now CISPR 32) when performing telecommunications line conducted emissions testing. A simple thing to correct, and it was written up. The laboratory showed photographs showing the discrepancy had been corrected. The next visit showed the error had been re-introduced. One audit is not enough.
ANSI C63.4 has, since 1991, required what is colloquially called “bore sighting” of antennas when testing radiated emissions above 1 GHz. Make sure the laboratory has the needed antenna mast to perform this test if testing is to be performed for approvals in the U.S. The first time I visited laboratories in a particular country none of the laboratories visited had such masts. And this was many years after 1991. The next time he visited every lab either had one, or had one on order. Seems the word gets around when a company representative stirs the pot a bit.
Documenting the assessment
Put together a quick checklist of items that you know you will need to look at in the laboratory itself. You can check off the items that are not right so you can write your report later on. Be sure to use a proper format when documenting deficiencies so that the laboratory cannot challenge you on any of them. Provide specific citations of what standard requirement was not met. Remember, if you can’t show objective evidence, it isn’t a deficiency. Just because it isn’t the way you would have done it doesn’t necessarily make it wrong. In the next article I’ll talk about some specific examples to help illustrate this point.
Conclusion
Auditing a laboratory prior to using them is important. They may be accredited, but the on-site assessor may have missed something, something that could be vitally important to your company. It’s not a simple thing to do, travel will be required, and you (or the consultant you hire) must know the standards and what they require. But, regardless of the cost, it’s cheap insurance to prevent unpleasant surprises from regulators. Also, remember that just because you found a deficiency or two the lab isn’t terrible. I’ve never performed an audit without finding something to write in the report. That includes in-house labs, as well. The audit is always an opportunity for a laboratory to improve their processes.
