Which device is not typically used for automatic control in electrical systems?

A toggle switch is primarily designed for manual operation, allowing an operator to turn a device on or off with a physical action. Its fundamental purpose is to provide a straightforward means to control the flow of electricity by closing or opening a circuit as needed. This tactile control does not incorporate any automatic features or feedback mechanisms, which are essential for automatic control systems.

In contrast, devices like relays, thermostats, and sensors are all geared towards automatic control. A relay can switch electrical circuits automatically in response to other input signals—this operation is triggered by the electrical current itself or other controllable parameters. Thermostats are designed to maintain a desired temperature by automatically activating or deactivating heating or cooling systems based on temperature readings. Similarly, sensors detect various environmental parameters such as light, motion, or humidity and automatically adjust the operation of electrical systems without direct human intervention.

Thus, while toggle switches serve a valuable role in manual control, they don't possess the automatic functionalities characteristic of the other devices listed.