I have been trying to control the grid circuit (Germany, 230V, controls 3 50W compact florescent bulbs) using a relay and Arduino Nano 5v pin. It usually works as expected, however sometimes it sticks to the on state (Both when connected through NC or NO). Namely, sometimes if the lights on, they will never turn back off. So far, only waiting seems to be a working fix.
I don't know about the circuit diagram of the relay, but the product is hyperlinked. Basically, live and neutral of an extension cord was connected to the COM1-COM2 channels, the output was both either NC or NO. And the signal (white) sockets were connected to each other with another cable.
So, I have limited electronics knowledge, and basically trying to understand what is happening and how to fix it.
Edit: Correction to voltage, specifications for bulbs + relay