Switches and Circuit Protectors Switch – a device that allows you to “make” or “break” the connection between two or more points in a circuit 1EGR 101

Poles and Throws EGR 1012 Pole – the moving contact Throw – the non-moving contact Example : Double-Pole, Single-Throw (DPST)

Normally Open and Normally Closed Switches EGR 1013

Rotary Switches EGR 1014

Dual-in-line-Package (DIP) Switches EGR SPST DIP Switch Circuit Symbol

Fuses EGR 1016 Fuse – a device that is designed to open automatically if its current exceeds a specified value Actual glass fuse Circuit Symbol

Fuse Ratings EGR 1017 Current : the maximum allowable fuse current before it blows Voltage : the voltage across an open fuse that will cause the air in the use to ionize and allow the open fuse to conduct. Fuse ratings are engraved on the metal end caps

Types of Fuses EGR 1018 High-Speed Fast-Blow Instantaneous Normal Instantaneous Time Delay Slow-Blow

Precautions When Replacing Fuses EGR 1019 Make sure all power is removed from the circuit Only replace with a fuse of the same current rating Only replace with a fuse of the same or higher voltage rating Never replace with a fuse with a higher current rating

Micro Fuses and Integrated Circuit Protectors EGR 10110

Circuit Breakers EGR Circuit Breakers – not destroyed like fuses when activated Single – Pole Double - Pole

GFI (Ground Fault Interrupt) GFCI (Ground Fault Circuit Interrupt) EGR Ground Fault Interrupter (GFI) – common special-case circuit breaker RESET Button