EMC Testing – Growing Demand: The IoT rush is on, with more and more products becoming “smart” with the integration of computer circuitry. But, the circuitry needed to make a product smart also creates the need for EMC testing. With the significant increase in IoT and other smart products, there is also an increase in the number of products that must now be certified for both Product Safety (UL/CSA/CE) and EMC (FCC/CE-RED Directive).
The Key Question: When you need to have the product certified, and your quotation includes both EMC & Product Safety testing, which do you do first? Does it makes sense to do the EMC testing first? Or does it make more sense to do the Product Safety testing first? Of course some manufacturers are in such a rush that they propose doing testing simultaneously using separate samples. However, this may not be the best approach.
The Impact of Timing: Product Safety testing is part of an overall product evaluation process that typically can take 6 – 12 weeks at the certification agency. Whereas, EMC testing is usually a much shorter process being completed in a matter of days. This disparity can often lead to pressure to perform EMC testing first, especially when a shared sample is involved.
Our Opinion & Rationale: In our experience, if you ask an EMC engineer which should be done first, they always say “EMC Testing”. Consequently it appears that this opinion has propagated to the default position. However, we suggest that Product Safety be done before EMC testing for these reasons:
1) Why Safety First? Changes needed for Product Safety Compliance can have a significant impact on EMC testing, in some cases requiring a lot of expensive EMC retesting if EMC was done first. Replace power line components, re-layout a board, change mains wiring and cabling, relocate components, modify cooling/vents, etc. These are all common changes that generally require EMC retesting.
2) Why EMC Second? If changes are needed for EMC compliance, they usually do not have a significant impact on a Product Safety evaluation and testing. Adding or changing a power line filter to fix a conducted emissions problem could cause the product safety leakage current test to need to be repeated. This is a minor impact. Other than that, most changes are logic and ground level shielding and dampening modifications = changes that have little to no impact on a Product Safety Certification.
Summary: While product revisions needed for compliance for either Product Safety or EMC certification could have an impact on the other, we feel that it makes much more sense to insure Product Safety compliance first. The risk is much greater that expensive EMC retesting will be needed if EMC testing is completed first.
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