What do these symbols in ac connectors stand for?
By convention, relay contacts are shown in the de-energized state. 

The middle is the common. Top is normally open (connected to common when energized). Bottom is normally closed (connected to common when de-energized). 

Verify with a multimeter. 



The blue relay is a Sanyou type, very common and somewhat nasty pinout. 



Not enough information (nor desire) to speculate on residential wiring codes and permissible connections in Brazil.