A multitester or multimeter is a device which can be used to gather data about electrical circuits. A basic multitester can measure resistance, voltage, and continuity, while more advanced versions may be able to provide additional data. This tool can be very useful to have around the house, and anyone who plans on doing electrical repairs should most definitely use a multitester for safety reasons. Multitesters can be used with the current off or on in most cases, although using the device with the current on can sometimes result in damage to the device.
This device is hand held, and powered by batteries. It consists of two probes attached to a central pack which can be digital or analog. The device has a series of buttons or switches which can be used to set the type of measurement being performed. A rubber housing may be used to make the multimeter easier to handle.
Continuity, the most basic measurement provided by a multitester, determines whether or not a circuit is complete. For a continuity test, the device is set to “ohms” and AC or DC, depending on the current being measured, before the probes on the device are inserted into the circuit. If the circuit is complete, the readout will measure between 0 and .05 ohms. A measurement of infinity indicates that the circuit is open, which means there is a problem.
In addition to being used as a basic continuity tester, a multimeter can also be used to test for a ground fault, a very dangerous electrical problem. To use the device to look for a ground fault, the “ohms” setting should be selected before one probe is inserted into a terminal, and the other is placed on the housing of the circuit. The reading should be infinity, indicating that the circuit is open. Next, the probe should be moved to the other terminal, returning another reading of infinity.
Using a multimeter can help to narrow down electrical problems quickly, and to test repairs to an electrical system. Multimeters usually come with instructions providing information about all of the measurements which the device can perform, and indicating whether the power should be off or on before the tests are performed. As always, it is a good idea to know where the circuit breakers or fuses for a house are, so that power can be turned off quickly in the event of an emergency.