Self-certification for CE marking! Can you help?

Question

We build littlecomputers (for our own use, but we put them on other people's premises) out of rackmount boxes, mini-ITX boards, some peripherals and a little bit of box adaptation and customising cables.

I'm sure these qualify for self-certification, but I have no idea how we actually DO it for this type of product.

Can you advise?

Answer 1

You probably know the Mark is simply a conformity mark. It depends on the category of the device what requirements need to be met.

For yours a most likely conformance is EMC. Which means it conforms to Electromagnetic emission requirements. I am in Australia where the Ctick is used instead. However the same standard (we have re-labelled it) is used to establish conformity.
Recently I played a part in designing an automated shut off valve for chlorine dosing in water plants. In the end due to the lower wattage and the fact that all components were Ctick individually we were able to use a rationale to avoid certifying the whole device. Yours sounds similar in that you have to install your devices on site to a clients system. There is an exemption both for the low wattage and the fact that you can't guarantee someone Else's system as a whole once you install your device. Also if all your components are CE then you may have a argument not to certify. Another requirement might be because of the process being controlled. If there are hazards then you may be required to ensure the client is able to use the design to satisfy an appropriate SIL level (safety Integrity level). This would require a HAZOP or Risk Assessment to be documented.

To certify you simply need to find a certified laboratory that can make the appropriate conformity tests. Then get the results make application to the appropiate board and get the certification.

Here is a good site from Aus.

http://www.export61.com/export-tutorials.asp?ttl=eteu

Hope this is helpful. i will email you with my proffesional address so you can respond meaning i can send you documents that might prove useful

Answer 2

Firstly, I don't think CE applies to you as you are not placing these products on the market, that said:

You are building machines with fast switching components so it seems to me that self cert is unlikely to be a viable route....

Note that even if all the component parts are CE marked, this DOES NOT mean that the final assembly will pass!

I would guess that there are really two sets of regs that are obviously relevant to your application:

EMC & Electrical safety.

The electrical safety is potentially easy, just use an external power supply that is CE marked (and that you are satisfied complies)! If you have to use an internal psu then things get a fair bit more complex.

EMC is where your problems will really start as computer logic boards are a notorious source of broadband noise, you will almost certainally have to filter all IO connections and take care to keep any slots in the box to minimal length (so they do not act as a slot radiator). For these purposes a lid that only makes contact at the screws counts as a series of slots....

Particular connections to pay attention to are the power feed (a ferrite ring often helps here, but then you need to measure, and any signal cables that directly export the motherboard 'ground' on the screen...

If you can get your board supplier to provide measurements showing that their boards will comply in your case and with your external wiring then the TCF route may be possible (basically you document that your system complies based on the noise power spectrum of each of its components), but I would be very surprised if that worked.

I would be very tempted to put an example (together with appropriate cables thru a test house for a preliminary survey even if I was basically going down the TCF route.

Sorry to be the bearer of bad news on the self cert, but as I say, I don't think you even need to CE mark (Check this with a specialist).

Regards, Dan.