When you need to test or troubleshoot an electrical circuit or individual components, you will use a multimeter. Combining the functions of several meters in one, a multimeter can measure the various properties of an electrical circuit, including voltage, resistance and current. Resistance, measured in ohms, can diagnose whether a component is faulty or distinguish between a short and a break in a circuit. A Craftsman Model 82141 digital multimeter provides a digital readout of the needed measurement.
Turn the dial of the Craftsman multimeter to the highest range in the section labeled with the Greek letter omega. This represents electrical resistance in ohms. According to the Craftsman Multimeter instruction manual, the resistance ranges vary from 200 ohms to two megaohms, or two million ohms. Adjust the range downward as necessary.
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Turn the power off to the circuit or device you need to test. Turn off the circuit breaker switch to test electrical sockets, or remove batteries from handheld devices. Allow one minute for residual current to dissipate.
Plug the red test lead into the right-hand socket on the bottom of the meter, marked "V-ohms-mA." Plug the black lead into the center socket, marked "COM."
Touch the leads to electrical contact points such as battery terminals or the terminals inside electrical sockets. Take the reading. Infinite resistance, or "OL," indicates an open circuit, which carries no current. A reading of 0 indicates a short circuit.
Turn off the meter and unplug the leads when you finish testing to conserve battery power of the meter. Turn power back on to electrical devices.
Avoid holding the probes to the contacts for more than 30 seconds. Always ensure you have dry leads before using them. Moisture lowers electrical resistance.