would thus turn mains voltage? Rather not. The optocouplers are used to control the transistors then drive the widerum the relay. For the relays, you can choose its own supply voltage. However, since the GND of relay Supply and GND opto-input is connected I see no added value of the optocoupler. In order for the drive side is not really separated over the optocoupler.
The relays have a pinout that leads in conjunction with board layout that at one point a little creepage distance between the mains voltage and "control part" is created. With a small layout change that would be wonderful to be solved. As I said, for my purposes for isolated switching 48V at max. 2A is not feasible at the price itself.
