Use "electrical switch" in a sentence

1. As he reaches the end of each line of the song Billy fights back tears, fights back images of artificial ventilation and a hand hovering over an electrical switch

2. The last door led to a tiny kitchen, and off that was a guardroom, complete with TV monitors, a panel of switches and the electrical switchboard

3. The solution is to have the heater operating until the cylinder expands (elongates) to a specified size and then have an electrical switch to switch off heater power supply