sure to "tag out" the switch to ensure that power is not applied to the circuit while you are working. When
work has been completed, power must be restored to the circuit. This will allow you to check the proper
operation of the circuit and place it back in service. After the circuit has been checked for proper
operation, remove the tag from the power switch.
Many electrical devices are used some of the time and not needed at other times. Circuit control
devices allow you to turn the device on when it is needed and off when it is not needed.
Some devices, like multimeters or televisions, require the selection of a specific function or circuit.
A circuit control device makes possible the selection of the particular circuit you wish to use.
TYPES OF CIRCUIT CONTROL DEVICES
Circuit control devices have many different shapes and sizes, but most circuit control devices are
either SWITCHES, SOLENOIDS, or RELAYS.
Figure 3-1 shows an example of each of these types of circuit control devices and their schematic
Figure 3-1.Typical circuit control devices: RELAY COIL TERMINALS
Figure 3-1, view A, is a simple toggle switch and the schematic symbol for this switch is shown
below it. Figure 3-1, view B, is a cutaway view of a solenoid. The schematic symbol below the solenoid