if somebody has no formal certification about working with mains electricity the only way to do on / off switching of mains-voltage-devices is to plug such a certified plug:
into this kind of certified sockets:
Even those popular S-ON/OFF devices need to insert blank wires and tighten screws which already requires the formal electricity certification.
Hacking the RF-remote-control of such switches is one way to achieve this. But needs some extra effort.
Does anybody know of a device that is a ready to use and CE-certified socket with a 3-5V input?
best regards Stefan