CE/EMC - Is it needed for... - Page 1
Forum section: electronics / projects

author: WanaGo
author_rank: Regular Contributor
timestamp: May 24, 2023, 07:59:02 am
content: Hello,Please assume nothing, but just after some general information.Say I work at an electronics company, and we make low voltage DC products (run on 5V or 3.3V), which get sold at distributors like Mouser / Digikey etc. Microcontroller based things basically.Distributors need CE/EMC testing on many things these days, or UKCA, along with the basics like RoHS and REACH etc.I am wanting to know what sort of things need testing.The actual main products, which have the microcontroller in them etc, sure - these need testing for CE/EMC.But what about Adaptors? Adaptors being a thing (maybe a PCB) to connect say our main product to another product, say a sensor based product to an Arduino or Raspberry Pi etc. If the adaptor is 'dumb' and doesnt have anything really in the way of electronics on it other than say passives, then I assume this does not need testing.If that is the case, what would the excemption be called for this to tell distributors?What about programming adaptors. Say it has a FTDI chip on it (USB to UART), or Silicon Labs, or who ever. Do those need testing for CE/EMC? Literally USB to UART to program a main product.Some 'professionals' we have spoken to say everything needs to be tested, which is a huge cost prohibitive process for our tiny company.Some say only the main products need it, but have not given any info on the programmers, or what we do for excemping the dumb adaptors etc.Does anyone know, just in general terms, what does and what does not need it, and what the exception would be called we label on things which are 'dumb' and literally just a glorified cable harness (dumb adaptor) ?Some distributors are threatening to pull product from their shelves if we dont get certification, even for things like a tiny wire harness. What certification do we need, or exception, is required to satisfy them?Everything is low voltage DC with no interface to AC at all.Thanks in advance

author: hans
author_rank: Super Contributor
timestamp: May 24, 2023, 11:17:41 am
content: You can put 2 boards together which are CE marked (say an Arduino and some kind of shield), but the combination is not CE valid. So you (or your customer) would then need re-test for CE.But it matters about what you sell.E.g. a board with a NE555 timer to drive a blinky can require CE, and fail it. If the NE555 is driving hard edges on a long enough cable, it will become an EMI problem, which is part of CE. So a manufacturer may include a cable and "demand" that you only use their cable with their product. It's unlikely that a different cable will blow up the device, however if their supplied cable is super-duper shielded, it's their way of making it through the CE testing.Likewise a cable on it's own is "little" to EMI certify. However, it still needs, to be safe: e.g. mains cables shouldn't expose live wires, and a cable harness shouldn't have loose strands or fall apart to potentially create shorts.But note that only a few industries require full test reports before you can sell stuff (like some medical equipment). I think a lot of products are self-certified. Only when someone is making complaints you would need test reports, where a 3rd party report can help a lot.For example, a FT232RL converter board can have no EMI problems if just plugged into a power source.But then you may start to use it with some device. Sending a ton of FFh's vs a ton of 55h's will create a different EMI pattern. Using a 10cm cable versus a 10m cable can also make a difference.So normally, for any kind of CE certification, you'll also need to lock down the software versions and equipments that's used during the certification.For example:https://ftdichip.com/wp-content/uploads/2020/07/DS_USB_RS232_CABLES.pdfIs said to be CE complaint. While:https://ftdichip.com/wp-content/uploads/2020/07/DS_USB_RS232_PCB.pdfIs not. I'm guessing because it's intention is to use with a cable, and since it's not included, what is the value of CE?Note I'm not a CE expert and this material is not my hobby. But this is my understanding I've collected over the years, and I'm happy to be corrected if I missed any detail which undoubtedly I will.

author: Haenk
author_rank: Super Contributor
timestamp: May 24, 2023, 01:10:07 pm
content: "CE" now does include RoHS/REACH - so even passive components, adpaters, cables and so on need a) the CE marking and b) a declaration of conformity. If you can trust your manufacturer of your passive adapter, that would easily be a case for a self-declaration IMHO. As soon as it gets into the "active" side of things, you need to consult a lab.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 24, 2023, 01:25:35 pm
content: MCU stuff: sell them as development boards. User is responsible for any interference they generate with it, no guarantees of operation, etc. etc.A trivial exception would be if your device can have wires attached to it, which are driven by the MCU inside, which is programmed with user code. User attaches a long wire. User sets wire to buzz at the clock frequency. User now transmits considerable EMI. What can you do about that? Absolutely nothing. So you can't get approval on something like that. Or at least, it wouldn't be very meaningful if you did; or might be a bit disingenuous to say you did.Likewise, programming adapters, probably various kinds of communication adapters / interfaces: lab equipment, to be used by authorized personnel in a laboratory environment. May create interference, may be highly susceptible; no way around it, some things just are that way. (Riddle: how in the hell could you get (conventional) CE approval for, say, a lightning generator?)Anything that you can get (conventional) approvals for, likely should. Yes, it will be expensive.Some items may have other controlling standards -- unrelated, but similar in spirit. The full and proper USB trademark requires licensing from the USB Implementers Forum, which may include performance and fitness standards, I'm not sure. These will be parallel to -- but distinct from -- CE approval. I would imagine compliance with any such standards will help CE approval as well -- that is, if the standard says you need a shielded cable with insulation covering it, and CE says your shielded cables need insulation over them, well, there you go, right.What did the distributors say you need to do? Do that. If they can't be very specific (e.g., it needs "CE", but there are numerous ways you could apply that, including by exemption), then drill into the standards they're asking for. Granted, the scope of "CE" is pretty damn broad, so that could take a lot of drilling. (Perhaps this is precisely the point you've reached, and need to know more about CE to go further?)Tim

author: switchabl
author_rank: Frequent Contributor
timestamp: May 24, 2023, 06:35:33 pm
content: There is an exemption in the EMCD for "inherently benign equipment":QuoteThis covers things like cable assemblies and passive adapters (but should not be mistaken to includeseeminglybenign "low frequency" circuits). The EMCD does not apply to those, however they may or may not need a declaration of conformity (and CE marking) for RoHS.You may have noticed that there is also an exemption for "evaluation kits" but don't get your hopes up, it is extremely narrow (essentially just made-to-order items for research institutions) and almost certainly won't apply to you.Apart from this, there is also the question whether your are selling a "finished product" (or "apparatus" in the context of the EMCD specifically) that is "intended for the end-user". Something like a bare-bones SOM where the customer needs to design their own PCB around it first would almost certainly be outside the scope of the EMCD.A SBC like a Raspberry Pi on the other hand you can use as "intended" by just plugging in some (readily available) power supply, keyboard and HDMI cable. You can build your own periphery but you don't have to for it to be useful. You can very likely make it non-compliant by adding a bunch of wires and programming it to output a fast clock. But it has a CE mark and can't be non-compliant when it is used as a normal computer.As you might expect, there is some grey area in between. You could argue that e.g. a sensor breakout board doesn't do anything on its own and might be used to build who-knows-what. However if you are also selling a microcontroller board that plugs into the sensor, along with convenient libraries or code examples, things are not so clear anymore. The overall intended end-use might simply be as a development platform and crucially, components that are intended to be combined by the end-user are also explicitly covered by the EMCD. You'd have to discuss this with the distributor.In any case, you wouldn't have each item tested separately but would likely test your main board with various accessories attached and declare compliance for each component based on a common test report.

author: SiliconWizard
author_rank: Super Contributor
timestamp: May 24, 2023, 07:05:29 pm
content: Note that if your product is to be used with some cables/passive adapters, then it has to be tested in a configuration with those connected to your product, and if it is to be connected at the other end to some significant load, using an appropriate load so that the test mimicks the worst case reasonably.Cables are not tested independently, but along with your product.This is usually when some cables end up with ferrites on them.