In a control circuit, what device is used to ensure that the motor does not start accidentally?

The device used in a control circuit to ensure that the motor does not start accidentally is the emergency stop button. This crucial safety feature provides a quick means to cut power to the motor and halt its operation immediately. It is designed to be easily accessible and recognizable, allowing operators to react quickly in case of an emergency, thereby preventing any unintended motor activation that could lead to accidents or injuries.

While the other options serve important functions within motor control circuits, they do not specifically address the need to prevent accidental motor starts. An overload relay protects the motor from overheating by interrupting power if it draws excessive current but does not prevent startup. A limit switch is used to control the operation of a machine or motor based on its position, not specifically for emergency stops. An indicator lamp provides visual feedback regarding the operation status but does not have any role in preventing the motor from starting. Thus, the emergency stop button is the best choice for ensuring safe and controlled operation of the motor.