3 ms·luckily all light switches have a light indicator show the current status.by gpderetta 4y agoluckily all light switches have a light indicator show the current status.jameshart 4y agoExcept when the bulb has gone. Which is the one time you really want to be sure the power is off.gpderetta 4y agoIn that case removing the broken bulb and sticking your fingers on the metal bits also works.