How a Silvia Works
All wiring
Off
On, heating up
On, at temp
Brewing espresso
Steam, heating up
Steam, at temp
Pumping hot water
Overheated
Modification for PID
Dual Setpoint PID
Advanced Dual Setpoint PID

Coffee Cup
Silvia is Off

As you can see here, the power switch is in the "Off" position. No power can get into the machine past the power switch. Of interest is the fact that both the common and the hot leads are controlled by the switch for added safety. Note that even though both leads are switched, the leads at the power switch itself as still "hot" and present danger if the cover is removed. Always unplug the machine before accessing internal components!