Continuity Testing Tutorial

For example, copper tracks on PCB's or wires in cables must not be open circuit but continuous.

In the diagram, when the two "flying" leads of the lamp and battery setup are connected to the two ends of the same wire in the cable, the lamp will light indicating continuity. If the lamp doesn't light then the wire is open circuit (i.e. not continuous.) The tester is also useful for finding both ends of a wire in a cable, where all the wires are the same colour.

A test meter, set to measure resistance, can be used to measure continuity. Ensure that the meter is set to read low resistance. If you set the meter to read up to 100k then a resistance of 500 ohms will appear to be continuous.

Some testers give out a whistle when continuity is ok, so you can keep your eye on the job and not keep looking at the meter.