@exilit This will depend on the region for certification.
Where do I start?
Generally, most if not all devices will come with Test Reports for that region. i.e. The EU has an overall requirement, but there may be local variants that need to have an aspect of the device that needs a specific test report.
Once you have that report you can apply to a Certifying Authority for the issue of a Compliance Certificate (more cost). The Certifying Authority may (and usually does) find another aspect of the report that has not been covered, so occasionally you end up back to Step 1. Just as an example, the last Series of electricals I had certified took 18 months of back and forth communication between the Reporting Authority and the Compliance Company.
It burnt a huge hole into the budget, not only because of the cost, but also the delay in bringing products into the market.
There may also be different Equipment Levels, ie Level 1, 2 or 3. to contend with.
The device will have to comply with the requirements of these levels. In our region Level 1 is the most stringent and applies to all devices that the Consumer can come into direct contact, ie Switches and so forth. The level will determine the complexity of the reporting required. Devices that are designed to be installed by an Electrician in a switchboard and treated differently. (usually Level2)
You could argue that this device is for professional use and will be installed by a Qualified Electrician in a Electrical cabinet of some description, but it's really drawing a long bow when you manufacturer it yourself. On the other hand if you make it and use it yourself (don't tell anyone just in case it fries and burns the house down) then you have what you want.
Is your head aching yet? Mine did and still does at times, however I can sleep soundly at night knowing that we have taken all possible precautions and the devices are as safe as they can possibly be and if the issue lands in Court then I can waive the necessary paperwork to prove that we were not negligent.
To simply answer your question:
Any device that uses LV will require some type of Test Report and Certification if you intend to manufacture and supply these for sale.Just be using a signal or ELV to control LV does not offer a way around the requirement.
However as you can now probably see, it's just not that simple.
I hope this helps, it not complete but you need to do a look of research of the requirements relation to the Certifying of Electrical Equipment in your region and make the correct judgment. As a Start look up Standard IEC 60669 and all the parts that come with it as a generally primer.
