I initially used a DPST relay to switch both the live and neutral inputs of a computer, but someone told me it was a bad idea and that I should only switch the live input.
I live in Europe and here we have power strips with DPST switches. It is mandatory in some countries to install two pole switches in bathrooms. Plus RCD (EU equivalent to GFCI) is present on every plug (if the electrical installation was updated within the last 20 years that is).
But it's technically possible to plug your device into a socket that is not connected to earth (non polarized plugs)...
I know that the US system is completely different. So here's my question:
If I want to design a universal system with a relay that switches on/off mains power (ie 120V US AND 220/240V EU), what kind of relay is safest to use? 1 Form A (SPST) or 1 Form C (SPDT), 2 Form A (DPST) or 2 Form C (DPDT)?