There is some informations that I couldn't find anywhere about CE compliance in order to design my project, so maybe you can help me :

1) I would like to use a buck switching power supply instead of a RCC for room and costs purposes. Does the power supply supplying a radio module (ie 5V DC) need to be isolated from the main power supply line (ie 230V AC) from a CE compliance point of vue and failures risks ?

2) All product has to pass the EMI tests in order to be CE compilant, so what is the advantage to use a CE certified module compared to using a wireless MCU with integrated radio and designing an antenna from the ce compliance/test point of vue ?

3) I would like to use the CC2538 wireless MCU from TI using 6LOWPAN over the IEEE 802.15.4. I saw that none of them are certified (either CE or FCC). Can I use the fact that this MCU is IEEE 802.15.4 compilant in order to reduce the number of tests I have to go through in order to prove the CE compliance ?

Thanks for your help


1) No idea

2) There are two sets of CE radio tests: the generic immunity/unintentional emissions tests required for all products and the intentional transmitter testing required for radio systems.

You will always need to do the immunity/unintentional emissions testing but by using a certified radio module and staying within the conditions of its certification you can avoid having to do the intentional transmitter testing. [*]

3) If you are using a transmitter that doesn't have CE compliance then you must test it for compliance. Compliance to a given protocol is a very different matter, if it's 802.15.4 complaint then you may not need to perform any interoperability testing to sell the end product as such (I have no idea if such testing is required for that standard or not)

[*] This is admittedly a little bit of a grey area. In Europe you self certify which means in theory you don't need to test anything at all. However that wouldn't really count as due diligence if the certification was later questioned and you could end up in considerable trouble if you can't show reasonable grounds for believing you comply.

However if you test your overall product for emissions and show that:
i) without the radio transmitter active it doesn't have significant emissions near the radio frequency
ii) you have documentation that the radio module has been tested and shown to comply under a certain set of circumstances and
iii) you can show that you have treated the module in the same way as under the manufacturers tests.
Then it is reasonable to expect that your implementation will also comply. You can certainly get away with a far more limited set of tests, e.g. show that the peak power is the same or less than in the modules stand alone testing and it's hard to come up with a way in which you could then fail if the module passed.

This link gives a reasonable summary on the state of modular radio approvals in different countries.
This link is specifically on the approval of products using ZigBee modules.

  • \$\begingroup\$ Please could you give me a citation for "by using a certified radio module and staying within the conditions of its certification you can avoid having to do the intentional transmitter testing" - I have in the past heard the opposite. \$\endgroup\$ – pjc50 Feb 1 '17 at 16:45
  • \$\begingroup\$ @pjc50 It was a little long for a comment so please see the update to the answer. I suppose in the end it comes down to how paranoid you (or technically the person signing the DoC) want to be on the testing. \$\endgroup\$ – Andrew Feb 1 '17 at 17:24
  • \$\begingroup\$ Thanks, that explains quite a lot what was shady to me. I will try to find a manufacturer tested IC and if I can't, I ll pass the intentional testing. \$\endgroup\$ – F.Jean Feb 2 '17 at 8:13

1) This depends highly on the application, but start with the Low Voltage Directive. Roughly: If there is any chance of a human touching a conductive part it better should be isolated against mains. The touched part should not be dangerous (voltage, stored energy) or it should be protected earth PE.
You are responsible to know the applicable standards. Keep in mind that the application of your product matters. E.g. toys, medical instruments or food processing have specific additional standards, which have to be fullfilled. These product and product family standards supersede the generic standards if applicable.

2, 3) Using a CE certified module increases the likelyhood, that EMI and susceptibility do not get worse by adding that module into your product. You still have to certify your product. The certified module does not let you skip any tests. The module interacts with the rest of your product and you or your company are responsible for the product and its certification as a whole.

If you are responsible for the certification, be sure to look up all required standards and test them (or let them be tested by an external lab) and try to get experienced assistance on this topic. Online questions probably wont cut it. Putting a CE label on a product, which actually does not fullfill the required standards, can get expensive for your company and potentially dangerous to people.

  • \$\begingroup\$ Thanks. I already planned to ask for an external lab tests. I'm evaluating the costs of the solution in order to have a more cost efficient module. I already contacted an external lab but its answer on the radio certification was quite shady. It's much clearer now. For the Low Voltage Directive, I read it yesterday :-). I don't need any isolated power supply considering this directive but I'm conserned about the unintetional radio fréquency emission in cas of a failure of an non isolated power supply on a radio module for compliance purposes. Do you know if that is a requirement ? \$\endgroup\$ – F.Jean Feb 2 '17 at 8:16
  • \$\begingroup\$ Is the failure that you have in mind, that the RF components would somehow be powered directly by mains when the supply fails, then possibly radiating a lot more? That would be hard to test and I do not know if it is required. It would probably be easier to show, that the supply will not fail or fall into a "save fail mode". E.g. testing the system against effects like voltage transients on main or when the output is short-circuited. Be aware that a switched power supply can generate lots of EMI by itself, good layout and design are key here. \$\endgroup\$ – Grebu Feb 2 '17 at 10:21
  • \$\begingroup\$ Yes, that was what I was thinking of. I suppose it makes sense considering the others protections required. Thank you for your help \$\endgroup\$ – F.Jean Feb 2 '17 at 15:10

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