Shabbat: Electricity/Electrical Devices: Turning Off

You may not turn off or disconnect an operating electrical device (such as an alarm, appliance, light, oven, or any machinery) on Shabbat, even using a shinui and even if the noise will prevent you from sleeping. You may ask a non-Jew to turn it off, but you may not ask a Jew, not even a child below bar/bat mitzva age.
Note If the device catches on fire, you may call the fire department or unplug it. However, there must be an actual danger or actual fire in order for you to disconnect it yourself.  You may not disconnect the device if there is only a chance that it will catch fire.