What is a short circuit?

Many times a short circuit is confused with what is referred to as an open circuit, yet they are complete opposites.

Electrical current will always take the path of least resistance. When a short circuit occurs, the electrical current flows from the designed path of the circuit to the path of least resistance either to ground or around an intended component.

An good example of what happens with a short circuit is the circuit used in an Overhead Projector that uses a diode (rectifier)to drop the line voltage from 120 volts to the desired 82 volts to operate a 82 volt projection lamp. When the diode in the circuit becomes a short circuit, the diode acts like a straight piece of wire and allows the 120 volts to go directly to the 82 volt projection lamp. Unfortunately for the end user, this short circuit will cause the projection lamp to burn out immediately.

If this was an open circuit, it would act like a broken wire and no current would flow through the circuit, and the projection lamp would not light.
Always remember, in an open circuit, the flow of electrons stops. In a short circuit the flow of electrons will continue either to ground or through other parts of the circuit.





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