This is a security feature. Most modern ovens allow you to set a timer with auto shut-off. This is very useful if you want to go out and come back to a ready me

This is a security feature. Most modern ovens allow you to set a timer with auto shut-off. This is very useful if you want to go out and come back to a ready meal. You can imagine what would happen if the power went out for a while and after it came back the oven switched on automatically. Refusing to turn on the oven when the clock is not set is the easiest way to prevent problems when it is in use.